/ohm/ - electronics general - chinese components edition

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Comming here because i don't know where else to ask.

My Xbox360 wireless receiver for PC recently died after a few years of use. I searched around and it was most likely a fuse. So i soldered across it, and now it works again.

However, i dont want to fry my USB ports.

Would it be better to plug it into a USB hub -> PC? Do most standard cheapo hubs have a fuse?

>>939511
our company took on a job of reconditioning an old SCR control system for an oilrig a few years ago.
really old shit. diode matrix cards, relays and everything.

we bought a small batch of metal cap lm741's
they where all good and legit national components, so we ordered much more from the same supplier.
like half of them failed in circuit because the offset pin did nothing, and we had issues all over.
a colleague pulled the cap it, it was a smaller brandless metal op-amp with national cap stuck on top. almost like in the OP.

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So I did what I should have done originally and put this on a breadboard before trying to solder it all together, and figured out how to get rid of the high frequency oscillation. Instead of trying to fuck around with a bunch of caps for local feedback in the voltage gain stage, all I needed was one from the op amp output to the inverting input (C6). -3db fall off is right before 20 kHz, but since it's a bass amp wired to a big woofer it's unlikely I'll need nearly that high response, even. I also had some pretty heavy DC offset on the output (150 mV), but that was solved by lowering R17 from 100k to 10k. It's going to be driven from a crossover with more 5532 op amps, so lower input impedance shouldn't be a problem.

>>939514
usb ports on the motherboard are also fused. but with polyfuses/clamping diodes so that fuse was complete bullshit to have. no problem. move on.

>>939524
do breadboards serve a purpose other than for children? if you design the circuit properly why cant you just go straight to soldering?

my electronics class in highschool was shit because they used the same kits and the ICs were always burnt out. everything worked at home but when time came to assemble at school it never worked.

>>939530
>design the circuit properly
if you aren't into simulating, testing parts of a circuit on a board can be a part of the design process.

i work in repair and recondition as noted in>>939520
when repairing old electronics you come across parts you cant source and has no way to test except building a circuit for it.
so we use a trainer to test it, then maybe protoboard a test board if we think we'll see more of it.
this is usually old DAC and ADC's aswell as weird logic etc.

>>939514
>letting the upstream fault detection do the work
This is how you cause housefires

>>939511
I'm thinking about trying electronics it as a hobby, what info and equipment should I get to start?
>Thinking a breadboard and some parts and just using web sources, but I don't know what parts and sources to use

>>939511
>buying anything from china
>ever

>>939565
good luck finding something not made in china faggot

>>939565
>this ancient meme

>>939562
Breadboard
A cheap digital multimeter
A cheap soldering iron
Some perfboards (protoboards)
Get a resistor kit (The ones that contain 3 or 4 of all common valued resistors)
Some basic components (Transistors, Capacitors etc but depend on what you are making)

Where's the best place to have a short run, <10, of 4 or 5oz pcbs made?

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Should I go hunt for broken rc cars for microcontrollers?

How do I find someone to put together a decently simply circuit for me?

I have no experience or tools with putting together circuits and don't really ever plan on going down that road.

How do I find someone/place to do it without costing me hundreds of dollars?

>>939651

a technical school or vocational school where they teach electronics. often in latter semesters, students have to build a project, and if they can get someone to pay for parts, then everyone benefits. just remember that you're dealing with dumb kids, so act accordingly, and maybe ask a prof instead to direct you.

>>939530
Clearly they serve a purpose because the circuit I was dealing with had a flaw which caused it to oscillate that the simulation didn't catch. I suppose of you designed your circuit properly every time you could go straight to soldering, but if your simulation can't tell you whether or not it's properly designed 100% of the time, you just need to be smart enough to tell whether or not its designed "properly" by just looking at it. I am not that smart.

>>939651
Is this a one off personal project or you trying to make a few bucks?

Hey guys, quick question

I need to interface a 5V Arduino with a 3.3V Raspberry Pi, so I was looking for a bidirectional level shifter to allow communication over serial between the two micros (4 channels of communication, RX, TX, GND, and a reset bit). I'd also GREATLY prefer through-hole mounting.

I'm having a bit of trouble finding something to fit the job. I checked Digikey, Mouser, and Jameco and haven't found anything quite right. Am I looking for the wrong thing?

>>939759
You can use a pair of MAX232s, no?

Hook their RS232 sides together, power one from the 5V Arduino, and the other from the 3.3v Pi?

>>939759
Use a resistor divider to lower Tarduino's output voltage to 3.3V level (like 1k/1.8k) and connect Pi's transmitter directly to Arduino's receiver.

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>>939703
It is a one off project and someone on the internet has already designed the circuit that I need.

Basically I got a treadmill for free and I want to use the motor. It is one of the new treadmills the digital inputs and I need analog. The PWM requires a specific set of inputs to function.

I could probably cobble it together on a test board, but I'm terrible at soldering and it needs to something that isn't going to stop working if it gets bumped because of a bad soldering job.

Attached is the circuit.

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>>939759
I'm on phone so sorry for quality being beyond shit, but shouldn't this work?
Lower voltage for Ard>RasPi, rise voltage to about 4,3V (well above Arduino's 3V threshold) with the Arduino 5V at collector/source

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>>939820
Forgot the pull-down resistor like the faggot I am

>>939820
Also collector/drain obviously

>>939642
Probably not, unless you're just gonna make more rc cars. Most of the micros they use aren't easily reprogrammable (if at all)

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pls help /ohm/

I'm trying to get the whole high/low-side switch notation right, I know that Q2 is a high-side switch since the load is located on it's source, and Q3 is a low-side switch since the load is located on it's drain. BUT does this logic apply to P-type FET's? Like is Q5 a low-side or a high-side switch?

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>>939642
Most aren't even worth it to salvage the chassis from for your own robots. Especially with how cheap things like pic related are.

Is there a secret to importing ti's pspice/tina models into tina/multisim or is it intentionally impossible for hobbyists? I just want to simulate a fucking PFC circuit.

hey /ohm/ first time here.

I'm slowly getting used to modding consoles for RGB / component output and other miscellaneous things.

i've been itching to put together a nixie tube clock kit but they're kinda pricey for me at the moment.

are there any fun / cool SMD board kits you reccommend?

anything on oshpark i could order and practice with?

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I bought one of those DC step up modules from China.

When I first connected a battery to it the right way diode started smoking since there was a sloppy soldering job that made that diode connect to one of the input terminals. Fortunately the sloppy soldering burned itself away and that diode isolated itself, so it now works as expected.

>>939982
The Chinese term for that roughly translates to "self-fixing"...it's a term that's used to explain sloppy jobs where the excuse is that the sloppy parts will nullify themselves with continued use of the product or service

Mostly used with street vendors of mystery meat containing foods and people who mass produce cheap ripoff items...it's considered an insult in the large majority of cases where it's used

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>>939820
>>939823
It's an emitter follower, so the output voltage will be around 0.6V lower. Straight wire works better than that.
If you're worried about the low noise margin of the direct connection, you can use pic related. Or you can use 5V 74HCT series stuff, like two 74HCT04 inverters in series. They have lower input threshold than normal 74HC, stuff but still have full 5V output swing.

>>939875
High side switch = switches the load on/off by controlling its positive supply.
Low side switch = switches the load on/off by controlling its ground/negative supply.

Switch type and the other details are irrelevant. Q5 switches the positive supply, so its a high side switch.

>>939875
High-side/low-side terminology typically isn't used with P-channel (or PNP), it would just confuse people.

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>>940095

I would like to broadcast some music to my old sony receiver using FM in stereo. Is there any way?

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>>939567
Infineon manufactures in Europe

>>939567
It doesn't matter so much where its made as much as where you buy it from. Regardless of where they were actually made, if you buy big capacitors or transistors from a US based seller, they'll be more expensive than if you bought direct from some chinese ebay seller, but there is much less chance of them being relabeled fakes. You have to pay extra for quality control, not for something that's not "made in china."

>>940289
The simplest option would be those tiny cheap FM transmitters they sell for cars so that you can use mp3 players etc. with old car radios.
If you want to build it yourself, you can use the same ICs used in those car transmitters. IIRC at least Rohm makes them.
A meme solution would be Raspberry Pi FM transmitter.
The idea behind FM stereo is also pretty simple (it's an old system, after all), so it is entirely possible to design and build your own solution from scratch.

>>940095
>>940090
Rightio thanks for that. Reason I was asking is that I was confused if I needed a high/low-side MOSFET driver for Q5, if I ever wanted to reduce Rds-on.

>>939511
>>939520
I don't know if this is fact or not, but I have read that ops pic was from somebody repairing old audio equipment with blown caps, they couldn't find any replacements that matched the original dimensions/looks, and they wanted to preserve its original appearance.
So they fabricated the replacement you see there.
if anyone knows the truth behind this feel free to add in.

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Hey,
I want to build a HHO-generator for my metal shop. I want to use it as substitue for an oxy/acetylen setup. The only thing I have some Problems with is the power source. I looked around and only found stuff for 200+€ wich is ratet for 0-48V and 0-60A

Per chamber i need 2V. So i was thinking i yould use a pc power supply wich is rated for around 12V and 30A. Build the cell in a way to put 4 different supplies on one cell. So i could save some money and controll the HHO output a litte.

Does anyone have some pointers for me?

Video:https://www.youtube.com/watch?v=AMlAOZArvA4

So, I'm working on a project with a decent number of AVR 328p's. At a minimum I will be using 6 that will have to communicate mostly signed integers to a single "master" chip for display on a small 16x4 lcd.

I started this project using i2c for the comms but I'm starting to wonder if I should switch to SPI.

The end result is going into a car and will probably have to be shielded from interference.

Each "slave" is connected to one or more sensors.

Which comms protocol would you gents use?

>>940514

Forgot to mention an important detail, the chips will all be within two feet of each other, in the same box, so pretty short distance communications.

The individual sensors hooked to the slave chips will be a maximum of 15 feet away, mostly simple resistance based readings.

>>940514
>>940515
Have you considered using a CAN network? It's pretty much made for this sort of thing.

>>940424
Yes, sometimes people do that to make the repairs less visible, particularly on very old equipment.
I'm not too convinced it applies to OP's picture, though, as you can still get similar capacitors and the used "replacements" have significantly lower voltage and capacitance ratings.

>>940386
Your primary problem would be that your IC already contains a driver for Q5 and its output levels are incompatible with any normal driver ICs.

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Does anyone have any experience interfacing with small form-factor LCDs, like the ones used in phones?

The only things I can find are either shitty low res (320x480 max), or require separate drivers because they just have raw RGB and require 10 billion wires, or are just Chinese bullshit on AliBaba with driver boards that have no datasheet, and no drivers anywhere, and won't work with anything.

What the fuck. Is it impossible to get a decent, sub 5" display that I don't have to reverse engineer / write a driver for, and can work over SPI, or DSI, or something relatively standard, but that isn't HDMI or USB?

>>940424
I've seen this done with old wax caps and such, but i dont believe that is the case in the pic.

why would they put in a cap with 1/3 of the value and go through the trouble of doing this to preserve the look of a bogstandard b-brand electrolytic?

>>940596
no you're fucked, it's the same thing with cameras. better start learning verilog faggot.

>>940386
> I was confused if I needed a high/low-side MOSFET driver for Q5, if I ever wanted to reduce Rds-on.
Neither.

Q5 is a bit weird because it's operated in reverse (i.e. current flowing from drain to source), which would make trying to describe it as "high side" or "low side" doubly confusing. The IC tries to maintain a 25mV drop when it's in the on state (it's used mainly as an "active diode" to prevent batter or charger current flowing back to the adapter if the adapter voltage drops).

If you wanted to use a FET with a high Vgs[sat] in that role, you might put a P-channel or PNP transistor (and a zener) in there to overcome the IC's -6V clamp on Vgs.

It's similar to driving the high side of a complementary pair (i.e. P-channel+N-channel or PNP+NPN). Which isn't what a "high-side driver" does; those are used when the high side is N-channel or NPN, meaning that the gate or base has to be driven above the supply rail.

>>940596
Yeah, fuck that shit. Just take the hit and buy one

>>940752
so if you have a 4 nfet h-bridge controlling a high voltage inductive load, you can't just drive all four fets at the same voltage? i'm a retard so the whole concept has me confused.

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I'm designing a pre-amplifier circuit for interfacing a temperature sensor IC with an A/D converter chip. The output signal of the sensor changes only 800 mV through the measurement range and I'd like to amplify it to 3 V.

According to simulations the circuit needs a 2.475 V reference voltage for the amplifier. Should I use a simple resistor divider for establishing this reference voltage? Or should I use a dedicated reference voltage chip such as the 2.5 V version of LM4128 or some adjustable model?

>>940794
you want to use like 4 resistors?
what tolerance? 1%? 0.1%? voltage reference will probably end up cheaper and less space.
or just use a 10k trimpot set it yourself.

>>940765
> so if you have a 4 nfet h-bridge controlling a high voltage inductive load, you can't just drive all four fets at the same voltage?
An H-bridge is pretty much the textbook scenario for high-side/low-side drivers.

A low-side driver is just a buffer (current amplifier) which can push/pull enough current to/from the gate to charge/discharge the gate capacitance quickly (to minimise the time the FET spends in the linear region).

The high-side driver is the awkward part. The high-side switch is normally an N-channel FET (N-channel FETs have better specs than an equivalent P-channel part), so the gate must be driven above the source to turn it on. But when it's on, Vds will be (ideally) a few millivolts, meaning that the source will be almost at the positive rail, meaning that you have to push the gate above the positive rail (which itself may be well above the logic levels an IC outputs).

So the high-side driver needs to level-shift, and it typically also needs to generate its own supply voltage above the positive rail. It's common to have a discrete charge pump type voltage doubler driven from the centre of each leg (i.e. high-side source, low-side drain), but that has the chicken-and-egg problem (it doesn't generate voltage until you start driving the H-bridge), so the high-side driver often includes its own charge pump to bootstrap its supply voltage.

>>940765
> so if you have a 4 nfet h-bridge controlling a high voltage inductive load,
If by "high voltage" you mean mains, or at least high enough that it poses a problem for a solid-state driver, then you'd use a gate transformer on the high side (a transformer with the primary between the (buffered) PWM signal and ground, and the secondary between the FET's gate and source). And possibly also on the low side, if only to prevent a fault from vaporising the logic-level parts.

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how are freescale (or I suppose NXP these days) with free software? Can I use kinetis chips with foss toolchains without too much pain? I'm tempted to get frdm-k22f board, seems like quite a lot of bang for buck if its actually usable. But its a big if, knowing embedded vendors in general...

>>940866
Personally i think the freescale toolchain is pretty OK, cant really go wrong with it. Better than the NXP LPC chain imho.

>>940866
他妈的白鬼

>>940879
>Better than the NXP LPC chain imho.
I sure hope so. I got burned once with the old lpcxpresso crap. I think I ended up spending more time reverse engineering the tools than actually using the HW.

>>940862
so if i tried to drive the high side of a 400v bridge with a 12v gate driver would it start oscillating on and off or reach equilibrium in some linear region?

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is there any lifehacks i can make with this? i want to install something like this somewhere but i don't know why i'd ever need a phone activation on anything electrical.

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>>940948
>lifehacks
>guide to a phone activated bomb trigger
I bet u could hack some lives if u know what im sayin brother
allahu hackbar amirite

>>940956
yeah i know. got recipes for bombs too but i'm not messing with explosives.
i just wanna know if anyone has any cool ideas on where a phone activation might be useful

>>940522
Isn't ic^2 meant for that as well though?

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>>940522

The car is pre OBD-II and I have no idea how to setup a CAN network from scratch (Any resources you can think of would be nice).

Google only seems to give me DIY canbus adapters and "HOW 2 HAK U R CAR" type shit.

I think I'm just going to stay with i2c and replace the wires I'm using with some 18/2 shielded boat cable I found in the back of my "wires and shit" cabinet.

No chip select line would probably help if I decide to expand it later anyways, I have no idea how far I'm going to go with this.

>>940983

And right after I posted this, I put more effort into my search.

A controller area network sounds fantastic, I see why cars use it now. Looks like I need to buy a CAN controller/transceiver.

I love the idea that all messages are broadcast and include an identifier. Gotta get a book and some more explanations on this, sounds exactly what I want.

And if I ever upgrade to a different ECU that supports OBD-II/CANBUS, it sounds like I could interface the two.

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>>939511

> Item location: Shenzhen, China

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I want to try controlling a capacitor charge/discharge into solenoid circuit with 2 MOSFETs.

Pic related is what I was planning to do. I've already tested the circuit with switches and it works.

Is there anything I need to add in order to protect the arduino?

>>941101
Looks like I drew the flyback diode in the wrong way.

It's connected the "right" way (opposite direction) on the breadboard right now.

>>941106
Was about to suggest that but you also need a ground reference for the bottom mosfet which is going to require a redesign.

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>>941110
How about this instead?

>>941121
Nope. The mosfet sources have to be both grounded in order to be drivable from the board (unless extra components are used). Try switching the negatives of both solenoid and battery.

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>>941125
I guess what I'm going for is a replacement for the toggle switch in pic related.

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>>941128

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>>941137
Thanks. Looks kind of like what I just came up with.

>>941138
Put a 47k between the gates and the arduino. That will reduce the chance of blow ups if you do something else wrong.

>>940961
IC2 is more general purpose. CAN is specifically designed for cars and systems which need a very low failure rate.

Every car sensor network in industry is done on a CAN system.

>>941217
Gotcha. Thanks.

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I made this.

It works, but the segments are very dim. I'm sinking the LEDs straight to a 74hc595 that is beneath the 7 segment display. When the segments are lit individually, they're bright enough, but when all 7 are on (which is something like 159 miliamps) they're not that bright. I guess it is because that's more current than the shift register can sink. Is there anything I can do to make the display brighter?

>>941248
Unless you want to remake it with transistors driving the leds

>>941248
Adding a shitload of transistor or a transistor chip

>>941258
What if I multiplex the individual segments really fast?

>>941263
Well it would have n times the current for 1/n of the time. I'm not clever enough to work out if it would be brighter or not

>>941270
Well, shit

It looks even dimmer

>>941248
>74hc595
that's one 595 per 7 segment digit?

you limited the current to ~5mA per digit right?

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>>941346

It has one for the pnp transistors on the digit (which are anodes) and one to wink the current of every segment. I should have used npn transistors to sink them rather than the 595 itself. One 7 segment module I have does that and it's so bright and pretty...

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>>941346

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Hello /ohm/, ctrl and 1 stopped working on my keyboard, I opened it up and immediately saw that some traces were darker than others. Can I fix it by taping wire strands along those burned traces?

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>>941400

>>941401
are they burned, or just on the other side?
of all the things to go wrong, traces are probably last on the list

>>941400
Do they work if you make contact by pressing the membrane itself?

>>941407

Nope, they don't work at all

>>941403

They didn't burn straight through, if that's what you're asking. They make no contact. What else could cause only 2 keys to stop working?

>>941410
well a trace serves more than one button so there would be other buttons fucked too
also there are 3 traces look different in your first picture so even if it was one trace per button it should be 3 buttons.

check traces with multimeter, try shorting out the fingers under the membrane. move membrane to push broken key with different membrane bit to figure out if its the traces, fingers or membrane.

which 1 is broken?
the 1 on the top row is keycode 49 which is 0110001 and ctrl is kk 17 which is 0010001
so in fact possibly your controller ic is having trouble with xx10001. bit out there mind you but unless you plugged your keyboard into a wall outlet the traces are probably not burned away to fuck.

>>941414

Top row 1. What's strange is that the darkest trace in the second picture corresponds to 1 and CTRL, and the dark trace in the 1st picture doesn't, yet only these keys have a problem. I tested the keyboard on keyboardtester.com, sure enough, 1 and ctrl don't work, but pressing the right ALT apparently toggled both ctrls and alts.

The controller might in fact be wonky, this keyboard used to restart itself from time to time for no reason.

>>940915
> so if i tried to drive the high side of a 400v bridge with a 12v gate driver would it start oscillating on and off or reach equilibrium in some linear region?
The latter.

I was going to say that you'd need transformers for that, but you can get solid-state drivers which can handle it, e.g. OnSemi NCP5181 half-bridge (high/low-side) driver goes up to 600V.

>>941414

I'm so confused.

I've tried rebooting my computer while it's connected, while it's disconnected, connecting it while it's on, while it's off, uninstalling drivers, all that jazz. After it didn't work, I opened it to make those photos and clean it, and when it didn't work I threw it on the ground, and it stopped working again. Connected it to another computer, didn't even light up.

After all this I connected it back to my computer and it's working again! I suppose letting it lie down for a long period of time and then connecting it to another computer rebooted the controller, and the keyboard works again.

But still, thanks for your response!

I'm taking a systems fundamentals class, and we're learning about making logic circuits in stuff, using gates to solve problems rather than microprocessors.

Are these kinds of hard-wired solutions really used much in the real world?

>>941423

Not really.
Some do; its snowflake stuff.

I do at work because reasons

>>941423
>>941425

Although I guess it is not that strange for everyone. People who work with FPGA stuff basically only work with that.

Forgive my ignorance.

What do you guys do with all this electrical and circuitry know how?

Like most other folks in various other hobbies seem to have an objective of sorts. But what is /ohm/'s objective.

When you build or repair a circuit. What do you manage yo complete? I understand there is enjoyment in the understanding of the electrical circuitry but is that really all?

>>941439
Why do you feel happy when you complete a video game? Why do you like doing your hobby?
Electronics are still "just" a hobby, but a very useful one at that.

>>941439
I personally am amazed by the concept of electricity, possibly the most awesome thing to me are capacitors and their ability to hold energy, it's like magic but real and very scientific and measurable
So I like doing a shitload of calculations and then applying it to see if it works, and the rush of happiness I feel when completing a circuit I designed is like a humble orgasm of the mind
I know it sounds shitty but it's the best and most accurate explanation I can give as to why I like electronics

>>941439
>When you build or repair a circuit. What do you manage yo complete?
You have a working circuit.

Like when you repair an engine, you have a working engine.

As far as what that circuit does...sometimes it's something stupidly useful, other times it's entirely pointless (there are people who learned to machine at a high level literally just so they could make little models of engines, no other use). If you're wanting a monetary justification for learning at least fairly basic electronics, almost every broken electronic device that you've thrown away could probably have been repaired with a little knowledge and some really cheap parts (compared to replacements).

But a lot of us are just tinkerers. We play with stuff. We learn enough about something to do a specific task, but we're mainly motivated by figuring out how stuff works and sometimes sticking different things together to make them do something different. It's not really about anything other than it's just how we think.

>>941439
i feel this actually a very valid question.
I repair electronics for work.
but what i work with and what i build separate.

when i got into electronics didn't really have much 'direction' so picking out projects was hard.
often googling around and browsing hackaday for stuff to do.
finding something worthwhile and doable enough to finish was especially hard when i was a noob, since the coolest stuff is often complicated.

now its mostly sound related stuff.
guitarpedals and tubeamps, started some synth stuff too.

got some clocks also, but they have been on the backburner for a long time.
my led sign project was dissembled for parts and never used.
got a shit ton of parts just laying around 2bh.
i think i should get more digital and MCU projects to diversify my skills a bit.

i hope to get my ass a bachelor in electronics engineering.
the curriculum was very interesting last time i checked.

>>941439
I've been building audio equipment. I built a bass guitar and now I'm working on an amp and some effect pedals. I can't actually play music well so I think I'm just tricking myself into thinking that more equipment will make me sound better. At least instead of just buying more and more shit like most people in that situation, I'm learning something about electronics from it.

>>941439

Before I knew any of this things pretty much looked like they ran on magic to me. Now when I open things up I have an idea on how they work an I could actually come up with one of my own.

>>941457
>I can't actually play music well so I think I'm just tricking myself into thinking that more equipment will make me sound better

lol, same boat mate

>>941446

That's the thing. I love playing video games but I understand that for me it is truly just a time waster and aside from specific instances nothing will come from them that i can apply to the real world. So to me I feel this is a bad example of what your hobby is all about.

>>941452

>you have a working X

This is where we differ. While it was a good feeling to hear my car turn over after the engine rebuild or the auto transfer switch operate by itself on the genset those things are only part of a much larger enjoyment. One which can state "finally I have transport again!!", "finally we have power in an outage!!!" and even "I am glad I don't have to buy a new washing machine".

>>941456

By most of these responses I can figure that my misunderstanding will come from my environment. Everything breaks all the time, no matter the quality. So everything I repair, it is for a reason. I don't know the basics of plumbing, electrical, hydraulics, mechanics, refrigeration, etc. by choice.

We have zero hobby shops here and even repairing basic shit is extremely tedious seeing as we are the kind of nation that can run out of flour, eggs, batteries, cement, light bulbs and god forbid you try to find a 14mm HSS drill bit

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>>941423
Basically it's like 50/50 whether you will or not. Still importabt to know, imo

>>939818
>555
there exist better pwm chips

>>940510
if you put pc power supplies in series, one of them will have to be ungrounded (otherwise the +12v from one will just to ground instead of through the other 12v) which is sooper dangerous. if you have cash just have someone wind you a transformer with your exact desired voltage and power rating, or do it yourself.

>>941613

Like what? I like the maxim ones with the minimal external components, but can't find it in a big enough package or breakout board

>>940593
>I'm not too convinced it applies to OP's picture, though, as you can still get similar capacitors and the used "replacements" have significantly lower voltage and capacitance ratings.

>>940668
>why would they put in a cap with 1/3 of the value


good point, Ive never actually looked at the values.
before I posted my post I did look at it and think about the fact that one was sealed and maybe it really was Chinese trickery, but then I also thought maybe he was trying to show a before and after repair.

My question in response though is if the outer cap is a b brand cheap shit cap, why would china go through the trouble of securing replica shells and fabricating a capacitor size adapter plate to plug the hole with and shove a smaller cap inside?
These are the same people that shamelessly make all kinds of botched jobs like not even soldering components down.

>>940956
>1 missed call
fucking lost

>>941137
>>941138
I tried both variations.

The solenoid does trigger, but it stays on for as long as the discharge mosfet is switched on.

I wanted the solenoid to only trigger briefly then retract no matter how long the mosfet was on since it was drawing energy purely from the capacitor.

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>>941655
I put a switch on the charge side and it works as I wanted it to, provided I turn off the switch before turning on the mosfet.

Pic related is the circuit now. Is there any transistor/IC switch component I can replace the switch with so I can control it with a microcontroller? It would have to take 60V and I don't know how many amps passing through it.

I would choose a relay but I don't like the extra "click" noise.

>>939511
I'm wondering whats the best way to integrate NFC to an arduino.

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What is the name of this part? I would describe it as "pcb mounted mains socket" but that gives me pretty bad search results.

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>>941708
Added a pic of the housing, you can plug european mains plugs into this thing.

>>941567
>importabt to know
like writing in cursive, filling out a check, or how to work a rotary phone?

>>941708
>>941709
its going to be a custom part
there is 0 chance you will be able to buy something like that
best alternative would be panel mount iec and matching cable.

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>>941682
Would a P-type MOSFET whose gate is controlled by an N-type MOSFET work as a replacement for the high side switch on the charging side?

>>941423
For anything but trivial stuff? Rarely.
It's a fundamentals class, you're taught that shit so that you understand other things better later. Colleges teach you lots of stuff which does no really have that much use in reality.

>>941426
Not really. Gate level design and manual minimization of logic gets very old very fast.

>>941729
Yes, but be careful to not exceed the maximum gate voltage rating.

>>939514
It would have been better to just replace the fuse

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What does /ohm/ think about the linearity of muh instrumentation amplifier circuit?

I went the easier way and used the dual op-amp version. That way I can have two instr. amp circuits with a single LM324.

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>>941423
They are used a lot in the industrial automation. The difference is that the logic gates are emulated in a microcomputer that is called a PLC (Programmable logic controller).

It is a simple way of making programs for the needs of machine control.

>>941423
In any case: there's a reason you can still buy 74-series and 4000-series logic, and it's not all for repairs.

Microcontrollers, FPGAs and CPLDs have drastically reduced the need for discrete SSI logic, but it hasn't gone away entirely.

Programming FPGAs or CPLDs still requires essentially the same skills as designing circuits using discrete logic gates.

A microcontroller isn't much use when you need low-latency.

>>941907
What was your common mode signal?

>>941761
That's not entirely true. At my job, we use FPGA and PIC all the time. An advantage of HDL over just using C is that it generally never fails on top of being much faster.

If you want to collect data from a sensor that cannot fail or someone will die then switch things on/of depending on the data received then HDL is a great thing to use.

>>941907
There is no good reason to use LM324s in audio equipment The slew rate is too slow to be useful and you're going to be cutting off a lot of high frequencies. AT LEAST use a TL074 if you demand a quad op amp chip. I don't see why anyone uses anything but NE5532s in audio with how cheap they are now.

>>942022
>TL074
i cant remember what way around it is but if you push the input up to positive rail the output fucking jumps to the negative rail.
I know its not supposed to be rail to rail but even a fucking hint in the datasheet would have been nice. apparently a common 'feature' of jfet opamps.
thats what i get for trying to get into analogue

>>942023
as long as you know, you can design it properly so that it doesn't clip. A linearly operating op amp should never have inputs anywhere NEAR the rails. If you just need a simple voltage comparator, that's where something cheap and slow like an lm324 shines.

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>>942005
The positive input signal is 2.33..3.13 V DC. The negative (reference) input is 2.25 V DC formed by resistor divider. Output signal is 0.3..3.3 V DC.

>>942022
I just want to amplify the signal produced by a temperature sensor for interfacing with an A/D converter. My previous post (and circuit) is here >>940794

With minor adjustments and resistor value changes I managed to improve the linearity. This circuit seems to perform much better than the previous one, which was a simple inverting amp.

>>942038
it was just buffering a dc signal but i had a spare opamp in the package. came about when i was testing input protection on adc, i was expecting it to clip to 5v but it was coming through as 0.i thought i had fucked it.
normal operating yes the input signal is well inside rails

>>941910
Is that some TwinCAT?

>>940948
This seems like an incredibly shitty design. Wouldn't it be way too easy to trigger the bomb while setting it up? Why not just remove the vibrator and hard wire your trigger to the circuit?

>>939511
what is the easiest microcontroller to use that isn't arduino?

>>942241
What's your aversion to arduino?
If you don't want to use or learn C you could try using PICAXE.

>>942247
I have an arduino and am looking to get something more low level but not a lot more difficult.

>>942248
Well, how low level are you wanting to go? Arduino is already fairly low level. If you really want to do assembly you could get an old Motorola chip like the 68HC11 otherwise the only way you're going to get lower level is writing structural HDL on an FPGA.

If you want to get into FPGAs, I highly recommend the Basys3 board. That being said, FPGAs are more difficult than PIC and AVR. Naturally, the more low level you go the harder it becomes. The thing that makes Arduino easy in the first place is the fact that it uses C which is a medium level language.

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I have this little 433MHz RF module set and I want to do cool stuff with it, the problem is it doesn't seems to work properly. When the reciever is connected it outputs a HIGH (or at least a very noisy HIGH), when it recieves the signal from the emitter it goes LOW as long as the emmiter is working, but if I go too far away this doesn't happens, instead, it just goes LOW for a fraction of a second and then it comes back to high.
I wonder if this is normal, I used antennas found in tutorials to maximize the range.
I guess If I can't get it to work I could put a 555 at the emitter to send a pulsed signal or put a "one shot trigger" at the output of the receiver.
I do not intend to use this with a microcontroller.

Thanks to the anon earlier who suggested I look into making my own CAN Bus.

After a fuckton of reading, I believe I understand it pretty well and I've got a few eagle files ready for etching.

I'm going to start out making three "nodes", each a single board with a surface mount atmega32u4, MCP2515 controller & MCP2551 transceiver.

If I get these all working and talking to each other, I've got a fuckton of useful and gimmicky things to try.

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I got one of these NEC FE700 displays at Goodwill for $4 on a fucking whim. It still works but it's too fucking big to keep on my desk. Any ideas for cool shit to do with the CRT? Is it totally out of the question to make it in to a usable oscilloscope since it doesn't use electrostatic deflection? Everything I've found from a few minutes of googling around are just people making music visualizers which is not worth the risk of zapping the shit out of myself.

>>942266
> Is it totally out of the question to make it in to a usable oscilloscope since it doesn't use electrostatic deflection?
Yep.

> Everything I've found from a few minutes of googling around are just people making music visualizers which is not worth the risk of zapping the shit out of myself.
There isn't anything useful you can do with it that a) would involve removing the case, and b) wouldn't work just as well with a flat-panel display.

>>942267
Welp it was a fun idea while it lasted. I can hopefully get some nice Nichicon and Chemi-con goodies out of it at least.

>>942268
I would only go for the ceramic caps, those will be as dry as a granny's vagoo.
Don't be a pussy and use the flyback for high voltage generation, you can do cool stuff with it.

>>942260
Maybe you could use a Schmitt-trigger NOT gate to filter the noisy digital signals and perhaps a JK-flip-flop IC to hold the current state in memory.

>>942266

I did this ages ago with an old television, wasn't accurate for any real use but made a cool visualizer and I hooked up a little amp I got out of some computer speakers.

IIRC, I swapped one of the deflection coils and had to remove the other one and cram it back in the case as it wouldn't turn on without it being plugged in.

I'd keep that beast though, I love CRT monitors.

>>942286
It is a nice monitor but I already have a desk full of LCD and lab gear and just don't have the room for it. It also has a deep gouge about an inch long right in the center of the glass that really bothers my autism. Plus I decided I want to build one of these fucks:
https://www.youtube.com/watch?v=Qw-NoKSqx58

>>942266

This is basically the top tier of crt that will ever exist.

This is the dusk of crt technology, some pretty amazing tubes are around for almost nothing now days.

They probably wont be worth anything but they will soon be basically irreplaceable.

Feed that into your hoarder algorithm and make your own conclusion

>>942331
Anon pls no. I already have a house full of random electronic detritus. Stop making me want to keep this thing. Have you owned this particular model?

>>942331
I feel sorry for the younger people who never knew the joys of using CRT monitors. Toward the end, even shitty CRTs gave so much better image quality than LCDs/plasma/etc. could ever dream of...but at the cost of being the size of a compact car.


I definitely don't miss moving that fucking 21" Trinitron up and down stairs during college.

On a side note, I'm kinda curious why everyone decided we needed more horizontal space when most sites work far better with more vertical space.

Fucking movie/tv optimization of computers.

>>942338
Web 2.0 let the normies in and fucked up everything. I keep my monitors rotated 90 degrees and in that format they are far better for doing work and shitposting than any CRT.

>>942241
You can use "arduino" boards as straight AVR, boards, basically by using it as a programmer, and omitting the arduino bootloader. You can use the bare chips in a breadboard, program in ASM, c or c++.

There's really nothing to hate about the AVR line, even if you're a hipster who seeing use arduino because it's popular.

>>942369
>even if you're a hipster who seeing use arduino because it's popular.
I readily admit to not knowing much about electronics, but I thought most of the distaste for arduino comes from it being overkill for most of the projects that they're used for.

>>942372
Well, yes and no. It is overkill for reading two switches and blinking lights in a pattern, BUT, it's also amazingly simpler than building a circuit out of 7400 series logic chips.

It's also overkill to use your car to carry home a gallon of milk from the store, but you value your time enough that you don't walk the four miles.

>>942383
speaking of arduino, is there a good project kit out there that comes with a bunch of random components, an arduino, and explanations of some things you can put together with it that you can buy as one kit, or is it all just buying individual components?

>>942395
buy a chinese clone on ebay. some kits have lots of stuff comming with it.
the clones work just the same.

use arduino.cc and other pages to learn.

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reposting because i couldn't find a solution yet

how can i force my crystal to oscillate on a certain harmonic when using pic related? in my case it's a 20/40/60/80/100 MHz crystal

i probably have to utilize a bandpass filter with the resonance frequency around the desired harmonic. i thought i would have to place said bandpass in parallel with the crystal, but it didn't work

then i thought an inductor in the feedback path might help, but looks like it doesn't

>>942617
Did you remember to charge your crystal by jacking it with a bro?

>>942617
Typically you'd put a series resonant tank in series with the crystal. Maybe add a resistor in parallel with the crystal to dampen its natural frequency, too.
Also, you need to use odd overtones and not all crystals work well when used that way.

>>942619
damn I forgot about that

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Can someone pls breadboard this and prove to me that it really works. I haven't been able to get this circuit ro work for a month.( Its dark detector btw )

>>942683
mfw the led could set off the photosensor

I don't know shit about ee but this circuit looks autistic. transistors typically require very little current to trigger, I don't think the transistor in this circuit would ever be closed meaning the light would always be on.

How is it suppose to "detect dark", if you just want to vary the led in relation to how bright the room is just put it like this " + > photosensor > resistor > led > ground" be sure to put a barrier between the led and the photo sensor so it doesn't fuck up the reading.

>>942683
looks good anon
what voltage is the supply
check the voltage at the base as you cover/uncover the ldr, should go above/below 0.7v play with the trimmer to tune it. shine a bright lamp/torch on the ldr and cover it completely to get a better variation.

make sure the transistor is the right way round and the right type.

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>>942683

I could tell it would work just looking at the schematic, but here you go. I have no idea how you're fucking this up, much less for a month.

The only two things I can figure is that your transistor is bad, or that your photoresistor offers the wrong range of resistance in the resistor ladder formed by it, the pot, and the fixes resistor.

Measure the resistance of the photoresistor. When light, it should be less than like 1/4 of the resistance of the top two resistors. When dark, it should be the majority of the resistance in the ladder.

>>942700
>I have no idea how you're fucking this up, much less for a month.

He's probably not using an NPN transistor. The instructions really should have specified that.

>>942260

Can you link the tutorials you used for your antenna design? I'm thinking of trying something similar.

As for your problem, you might be getting feedback since it looks like you are using the same power supply. Using a coupling capacitor in parallel with your VDD would help to limit feedback from your modules. A 10uF on each would probably do.

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How do I deal with this /ohm/? There are no pin numbers. Is there a standart for this or do I have to figure the right pins from the datasheet and the function?

>>942853
No standard, you read the datasheet and deduce the pin numbers by yourself. Plus any possible extra stuff that IC needs, like bypassing capacitors.

So i made a layden jar but im not sure how to charge it without using a pvc pipe, any ideas?

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>>942859
So uh in this case figure 6 would be the only one that makes sense right?

>>942260
Small radio modules are often AC coupled and you can't use them to send constant high or low. If that's the case with your radio, then your 555 idea would be the correct way to send constant signals.

>>942870
Looks like that.

>>941248
nice clock Ahmed

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I just bought for some flashing purpose an AVR Dragon and some socket.
Can this work installed like in picture without soldering or must I solder it ?

>>942917
what?
the socket should be soldered into the board unless its in some connector

the chip goes in the socket then pull the handle, thats literally the point of a socket, no soldering. zif socket is zero insertion force, you don't need force to put chip in and out

>>942918
I want to know if the zif connector is currently making contact to the board without any soldering.

>>942919
no, it's not making contact.
You should even be able to easily lift it of the board.

>>942919
probably not no
if its a tight enough fit you might get away with it

>>942693
>>942696
>>942700
Thanks for the help anons. Turns out i was being dumb and didn't realize i was using a pnp transistor.

>>942917

i was in a situation like yours, not wanting to 'waste' an expensive ZIF by soldering it in place. so what i did is solder a regular chip socket, then pushed the ZIF into it. I used a wire-wrap socket coz they're sturdier than most.

>>942917
How often are you going to need that one socket on another board? Why not just solder and then desolder it when another application for it comes along?

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Hello /ohm/, rate my meter.

>>943216
Pretty solid design, has reliable basic functions
7,5/10 for no AC, if it had current instead of voltage only it would've been 8,5

>>942917
If you really want to have it removable do as >>943125 said and solder a socket or female headers to the board and insert the ZIF there
But unless you are already using it for something (what?) do as >>943187 said and use the right part for the right job

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>>943220

I wouldn't put this thing in mains anyways - it cost me less than a dollar.
I bought it because this meter, which I've gotten for free after working as an electrician's assistant, wouldn't measure current despite the fuse being OK.

>>943216
>>943230
I've always had a thing for these dinky little cheap meters. They're kind of cute.

How do I reinforce wires soldered to a LED strip? I thought I did a good job yet my friend managed to break them. Heatshrink tubing? Kapton tape?

>>943246
They're physically breaking the solder connections? Why are they being so aggressive with it?

Anyhow, try using silver solder. Joints made by silver solder are stronger than 60/40. If they're breaking the metallurgical bonds, a heatshrink tube won't do much.

Tell them to stop being so violent.

>>943246
You mean the wires themselves or the solder joints? Why aren't the wires already heatshrunk?

>>943252
>>943250

The wires. It was supposed glued to the underside of a desk and they managed to swat it so hard the wire broke. I tried to leave as little exposed wire as possible, but I didn't want the insulation to melt, too.

>>943259
If the desk is fairly thick, you could use carpenter staples on the underside instead of glue. But you should definitely heatshrink them.

Otherwise, consider running the wire along the inner edges of the desk rather than through the middle or a place that is easily reachable.

>>943260
>>943259
>>943252
>>943250
>>943246


Now that I think about it, I think I'll solder thick solid core wire to the strip, and then solder the main stranded wire and heatshrink it all.
Thanks for all your responses!

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I know pic related can be programmed with just a UART interface, so you don't have to buy a programmer if you have a USB to UART thing already. Are there any other microcontrollers that can do this (preferably DIP because muh breadboard)?

>>943334
most of the STC 8051s can be serially programmed.

>>943334
ATmega328 with pre-programmed tarduino bootloader
Maxim's DS5000
At least some chips in the MSP430 family
At least some chips in the C2000 family

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>Instrument cluster is too dim in my car

Older car, 1995

I've already been through and replaced the bulbs with leds and they're a little bit brighter but still too dim. So far I've decided to just add more lights but I'm cautious of tapping into the power of my instrument cluster in case the extra load effects the instruments. I'd feel better tapping into it somewhere else and routing it to the dashboard. Anyone else had this experience?

I'm under the assumption that if I just add two wires to the leds already there and wire that to more leds in parallel that'll just draw more current and shouldn't affect the voltage? I haven't done this stuff since Highschool science class.

I'm just cautious because I don't want to fuck it up and have me speedometer give a wrong reading or drain the battery, and if you were going to ask I know it has a dimmer and I've put it on full, I don't think it's faulty either.

Pic unrelated

>>943454
is that some old skyline piece of shit? yeah they are built with the 100 000km limit in mind in japan. by that point the entire wiring harness is cooked.

>I will never work on a 300zx again

what voltage do you get on the VCC of the instrument cluster?

what voltage is your battery when the car is off?

what happens on these ancient turbo shitters is that the wiring harnesses are exposed to a ridiculous amount of heat that degrades the wires. you can do a simple patch job which just involves running a new wire from the battery terminal to the instrument cluster for the power. cut the old wire off and remove the fuse for the circuit. a simple fuse and relay combo can be used to fuse the circuit, the relay is for switching the console power to on when the ACC power is switched on.

>>942872
I used this http://m.instructables.com/id/433-MHz-Coil-loaded-antenna/ and for the emitter I wound 32cm of wire around a pencil.
I'm not using the same power rail, when testing I used a battery for the emitter with the reciever connected to my psu
>>942793
K thanks for the info!

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>mfw got a shitload of 2N3055's

I just tried to desoldier a gtx 500 series video card with a 20$ soldering iron from radioshack, but the soldier wouldn't melt. What was i doing wrong?

>>943614
Is the iron hot enough? If it was designed for leaded solder, it's not going to desolder any commercial PCB made in the last decade or so.

Did you tin the bit? A "dry" bit may not have enough contact area to transfer any heat.

>>943621
Well it was hot enough to melt the soldier it came with, and i have no idea if that was leader or not.

And yeah i did tin the bit

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>>943607
Apparently it went out of fashion couple of decades ago. I mean, at some point it was pretty much the default big transistor and every transistor maker produced them. Now, if you check big distributors like Digikey or Mouser, there are only few makers left and if you actually want to buy them, it's just ON Semi.
The same seems to apply to everything in TO-3, though.

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>mfw 8051 soviet clone in my pocket

>>943614
What kind of tip are you using? Cheap irons usually come with shitty conical tips that don't have enough surface area to desolder anything. You need a nice big chisel tip. Also, are you using desoldering wick? That usually helps to spread the heat out a bit.

>>943454

an LED that can output the same light as a bulb will take 5 to 10 times less power. so, you can parallel a bunch of them without worrying about anything. also, the power going to the lights normally has zero effect on the sensors, so no worries there either.

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I got this Miille Applied Research leased line modem from Fleabay for $1 shipped just to see what its guts looked like. I was not expecting a fully socketed chipset and an AMD AM7911PC microprocessor that seems to be the only obsolete part in there. The caps are 10uF Illinois Capacitor and 100uF Nichicon but I don't think I'm going to fuck with them since the date code on the AMD dates the thing at 20 years old.

Anybody know of a way to make the AMD do something useful other than act like a modem?

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>>943685

it's a modem, not a processor. nothing you can do with it except make beautiful chirping noises.

>>943666
Yeah I'm using neither of those lol.

I guess I'll look around for something better

>>943688
Ah OK. Thanks for the schematic. At least I can use the socket for something useful.

>>943790
that's a nice little wide input to dual rail isolated dc dc converter

>>943803
Yeah I'm holding on to that for sure. The little op-amp in there is pretty snazzy too.

>>943216
No need to label it. Everyone knows Fluke has a patent on yellow meters. Or at least believes they do.

>>943808
Don't know why anybody would want that color scheme anyway unless they were trying to pass their shit off as Fluke. It's ugly as fuck.

I have a project with a magnetometer, and it's measurement output is getting fucked pretty bad by batteries placed close to it, and I'm guessing just general noise from all the other electronic stuff. I managed to improve it a little by moving it as far away from the batteries as I could, but it's still pretty bad. Is there some way to minimize the effect to get more accurate measurements? I was thinking adjusting the gain might help, but I'm not sure.

>>943830
>bright yellow means easy to see and find
>ugly

>>943830
>Multimeter
>ugly
Unless form compromises function then you are retarded

>>944035
Yeah, everything fucks with them. In some situations (noise from electronics) averaging helps, but not always. Keep them away from everything if you can, provide them clean power supply if you can and filter as much as you can.

Or just ditch them and use something else.

>>944071
>Or just ditch them and use something else
I'm really considering this since I'd have to redo the whole power system if I stay with it (or rather make an actual power system instead of what I have now...).
What would you suggest? I'm just trying to get a robot to move in a straight line (without having to follow an actual line underneath/near it). I was thinking something OpenCV based instead? Like it could be tracking an object that it tries to keep "centered" and adjusts motor speed accordingly.
I also have an accelerometer lying around, but I don't have any idea of how it could be used for this purpose.

>>944075
accelerometer would be great.

Only allow acceleration in one direction. If you have acceleration in another direction, then force it to accelerate in a corrective direction/amount.

>>944078
don't know why this didn't occur to me.... will try it out

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The insides of this thing reeked like acetone. Anybody know why? Just curious.

>>942266
Could always cannibalize the flyback transformer to make dumb projects with arcs.

>>944143
See >>942296
I'm getting shit together to make a Marx Generator for some real mad scientist shit.

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>>942853
This anon again.
This one is a real struggle for me. It's supposed to demodulate a 21MHz signal and The only Datasheet I could find is
http://pdf.datasheetarchive.com/datasheetsmain/Datasheets-X2/DSA832000-21.pdf
I think I got most of it figured, but the pins 5 and 7 are a riddle to me. Do I even need them if all I want to do is demodulating?

>>944152
Dude, you have sketch-like schematics using obsolete ICs and you sound like a novice. I hope you aren't trying to build this.

That said, get the complete datasheet and possibly some better application schematic first. Pins 5 and 7 seem to be functions you use in some applications, but not in all of them. In other words, their use depends on the rest of the circuit.

>>944167
I tried to find more for quite a while. Guess you are right I'll have to give up on that one.

>>944182
Well, the datasheet can be found here:
http://www.datasheetarchive.com/dl/Scans-055/DSAIH000121213.pdf
For application circuit you could just google TV schematics, it's a TV chip after all.

But yeah, "guess the missing parts" game is not going to be amusing unless you're pretty good at it. If you aren't, you just waste your time and money.

>>944141
Acetone or isopropyl alcohol is often used to clean off Flux. It could just be some residue trapped inside the watch during manufacturing.

>>944035

Put in some shielding

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Its me again with thw dark detecting circuit. I got it working but im trying to find out how to increase the light output of the red 1.5v led. Using a 6 volt power supply.

>>944440
Reduce the series resistance (the 220 Ohms in the original schematic).

If that doesn't do anything, you need a transistor with a higher current gain (beta, h[fe]).

You can't reduce the resistors feeding the base because they're dictated by the properties of the LDR.

>>944229
Ah neat. I thought it had something to do with how the plastic was manufactured. Thanks anon.

>>943334

Most can if you want to write a bootloader or can find one for your device.

>>944466
Of course, but then he needs a programmer (or someone with a programmer) to program the bootloader first. Which is something he's trying to avoid.

>>943630
TO-3 costs more to make amd is thermally inferior to newer packages like TO-3p and TO-264.

>>941720
A bit more useful than that. You still see discrete digital circuitry used in some circuits.

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Anyone have experience with decoupling pin heavy components? I have a PGA-132 processor (Intel 386) which I'm trying to build a breakout board for. I went through the datasheet which suggested "liberal" use of decoupling caps. From past experience I've had with microcontrollers I've used ~0.1uF caps on all the Vcc pins with some ~1.0uF caps further up the supply chain and that has worked out every time. However: this bad boy has 20 Vcc pins and it is clocked to 33MHz. So, my question is: can the same capacitance values be applied or should I make some changes (possibly adding in some pF range caps)?

pic rel: playing around with ideas for routing

>>944080
if it's just a hobby/undergrad project consider getting a combo accel-gyro-mag breakout board, there's algorithms that synthesize the data to increase stability and prevent drift. with just an accelerometer you'll have terrible accumulating error. you can get the combo (9-axis) breakout boards for like $5 if you search so there's no reason not to.

>>944547
100n 0603 size capacitors work pretty well at 33MHz. If you're feeling paranoid, you can put 10n capacitors in parallel with them. They won't cost much.

That said, Interl actually has a document explaining what they mean with "liberal": http://microblog.routed.net/wp-content/uploads/2006/05/24072501.pdf
Note that they rely on a multilayer board to provide additional high frequency bypassing.

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Good morning /diy/

I'm finally putting together the biggest project I have till date. Long story short: LASER CUTTER

I need to operate a 40watt CO2 cutting laser. Are there good online resources as to the type of power supplies they use, and if it is possible to construct them. There is very little documentation about these chinese CO2 tubes, and what exactly is needed to operate them.

As far as I understand, they require a simple water flow cooling system. Along with a constant current high voltage supply (~20kv at 25-30mA). Is there something else needed to operate these? has anyone here had experience with these things in the past?

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>>944578
That app-note is pure gold from my standing point. Thanks!

Also, yes, I'm going with 0603, the last part I feel comfortable hand-soldering and I already have them around. As for multilayer... this smells like I'll have the board made in a shop.

pic rel: some progress

so ferrite core permeability for transformers and inductors varies with frequency, temperature, and dc bias current. i can't find a way to actually combine all those factors into a formula to find permeability at any combination of those conditions though. on the datasheet the dc bias current permeability plot is in terms of mu_rev, and the freq plot is in terms of mu' and mu'' but it doesn't say how to use those to correct mu_i.

am i missing something? can somebody help me out?

>>944581
Well, if you want 32b buses running at 33MHz, multilayer board would make sense in any case.

>>944660
Typically you use air gap to drop the permeability so much that the variations won't bother you too much.
If you want to combine parameters, you can normalize them and multiply the normalized values with each other to get a rough idea about the total normalized result. Then scale it with your initial permeability.

>>939511
I have a desktop light, just a simple one, how do I hook up my arduino to it so when I clap it turns off/on, I dont ask for the program or anything or how to work with the sensor, my problem is I SUCK at electronics so I cant really figure out a way to make switch that won't fry the arduino (since the lap uses 110 volts) and the arduino 9... any help ?

>>944684
> I cant really figure out a way to make switch that won't fry the arduino (since the lap uses 110 volts) and the arduino 9...
For any post which boils down to "I don't have a clue about electronics; how do I do stuff with mains voltage", the answer is: Don't.

Get a low-voltage desk lamp and use the arduino to control that instead.

The thing about anything involving high voltage (or high current or high power, for that matter) is that understanding how a circuit works is less important than understanding *all* of the ways in which it might fail, and that requires somewhat more comprehensive knowledge than is required just to make something work.

>>944690
>>944684
I was really just considering going 'relay, blah blah, gl brah', but in hindsight, keeping away from mains without any or perhaps misguided electronics knowledge might be a better idea.

But to point you to a possible solution that might not involve you killing yourself, don't use Arduino for this project.
A 'clapper' is a fairly simple project that's very commonly found as a kit that's very easy to assemble and you're working with something that's certain to function.

A word of warning, I was a smart fucker and wired the lights in my room to one of those.
Next week I got sick and started coughing.
You can imagine the pleasure I had when my lights started flickering in the middle of the night.

>>944691
>>944690
Thanks guys, I guess Im going to spend the next week understanding more and more of electronics

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So I'm thinking about building something like this 8 LED sequence, like the Velleman MK107 chaser kit

http://www.vellemanusa.com/products/view/?country=us&lang=enu&id=350682

What I had in mind is a setup where I could build another identical module, plug it in somehow and have it be 16 steps, rather than 8, simply by pluging it in (again somehow).

Sorry to be vague, but can anyone suggest a chip to start investigating which can do this and is somehow chainable to another one of itself?

pic unrelated.

Thanks in advance

>>944709
Honestly , you could get away with just a counter, a MUX, and a clock for this if you wanted to go super minimal. Just have an 8 bit counter connected to a MUX then have the carry go into the enable of the second counter. I'll draw you up a diagram when I get home if you like.

>>944728
Sounds ideal, thanks. What is a MUX? By clock you mean 555/556?

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>>944732
You could use a 555 if you wanted. I'd use a crystal oscillator.

A MUX is pic related. It let's you control multiple lines of logic with a binary input.

>>944576
The accelerometer I'm using also has a gyroscope which I've been using (with some success so far). But how would I involve the accelerometer output? As far as I can tell it's just a "tilt sensor". The robot I'm making only moves around on flat ground so I don't know how it would help at all.

>>944728
that circuit is unique in that you use the PROG button to enter a sequence of on/off bits and after 8 clock cycles it will repeat that entered sequence until the reset is pressed.

>>944756
What is this?

>>944751
if the gyro reports yaw, pitch, and roll then when your car turns it'll report an angular acceleration on the yaw axis. that can be combined with the accel info to reduce measurement drift.

the specific filter i used in a project a while ago to combine the readings can be found here (this one expects mag input too, not sure you can just exclude that) https://github.com/kriswiner/MPU-9150/blob/master/quaternionFilters.ino or you can google "sensor fusion" for more info.

>>944756
>>944760

not super practical. you'd have to slow the speed of the clock as you enter in the pattern, then speed it up to make it a 'light chaser', instead of a 'light crawler'. also, the switch should be debounced, and an LED should be added to the 555 so you can synchronize your button pushes to the clock.

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I found this pcb and i was wondering how do they get the solder to be like that?

I want to start making pcbs but i dont want to use the toner method since i dont have any of the stuff. If i could only use solder like the pic that would be way easier

>>944840
Your pic shows a board with etched copper traces that have been coated with solder in the wave soldering process. They still had to etch the board. If you don't want to etch stuff, just use perf board and wires.

I'm planning on adding a camera and IR emitter/sensor to a robot. They are going to be placed close to each other. Should I expect problems with IR noise to the camera due to the emitter? It's the Raspberry Pi camera, which they say has an IR filter, but I don't know if it'll be enough since I plan on putting them close together.

>>944815
LED chasers - serious business.

>>944840
Like the other anon said, that's the result of wave soldering. The board itself was etched.
It is possible to use solder as etch resist and electroplated tin (formerly tin/lead) is used for that purpose in industrial scale, but there aren't many etchants which are suitable for that.

>>944756

Why are the clocks of both shift registers connected? How does the first chip know when not to run? Thanks

>>944815
It would be more convenient to have two buttons ("off" and "on") and generate the programming clock from their logical-OR.

>>944930
The circuit is a single 16-bit circular shift register, made from 4x 4-bit shift registers (2 on each chip).

>>944930
They both run continuously. The second register shifts in bits from the first register's last output and the first register shifts in bits from the second register's last output. In other words, it's a ring and whatever bit pattern was loaded in will rotate through the registers forever.

>>944936
Is there software I can use to simulate electronic circuits like this?

>>944945
SPICE

>>944936
>>944936>>944936

Won't this leave all lights on or will they only come in sequence? Can a decimal counter be chained rather than shift registers? Many thanks

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How do i make a quick voltage source with 1V or a little bit below?
I am electroplating copper right now and want to plate silver, for that i will need 1V and nothing above 1.2V.
I thought maybe i could put 1.5 V batteries in parallel and then just lower the voltage with a series resistor?
Any help is greatly appreciated.

>>944946
Thanks, I'll take a look. The spice must flow

>>944945
>>944946
I'd suggest LogiSim for digital circuits.

Spice is an analogue simulator. While it can do digital stuff, it's far less convenient in the case where you're only interested in a digital model (i.e. all signals are "on" or "off" rather than analogue voltages).

>>944948
> Won't this leave all lights on
No. A shift register is a sequence of D-type flip-flops (1-bit memory) with the output of one fed to the input of the next. At each clock cycle, the pattern of bits is shifted down one place, with the first bit set from the data-in input.

> Can a decimal counter be chained rather than shift registers?
No. A decimal counter is just a counter with decoded outputs. In particular, exactly one of its outputs will be on at any given point.

You can use one as a "chaser" with only one "on" bit. You can't have multiple on bits and you can't chain them. With an up-down counter you can alternate the direction (Knight Rider style), although you can also do that with a bi-directional shift register, e.g. 74194.

>>944949
Connect two set of 3x1.5V in parallel to get 0.5V. Connect them in series to get 1V. Total 6x1.5V batteries.

>>944946
I use ModelSim at work everyday, but it's probably too overkill for simple hobby stuff.

>>944949
> I thought maybe i could put 1.5 V batteries in parallel and then just lower the voltage with a series resistor?
This is unregulated, so the voltage will vary based upon the current drawn. If the current varies as plating progresses, you'll need a variable resistor and a voltmeter, and manually adjust the resistance to maintain the correct voltage.

A regulated supply replaces the human with a negative feedback circuit.

>>944956
> Connect two set of 3x1.5V in parallel to get 0.5V.
WTF?

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>>944958
Alright thanks, i will try that.
>>944956
This does not make much sense to me but i am always excited to see an explanation.

>>944959
3x1.5V in parallel makes 0.5V. Make two of them. Then connect them in series.

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>>944961
here have a picture because my drunk ass can't explain circuits

File: batterus2.png (4KB, 796x492px) Image search: [Google]

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or you can do this

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>>944949
I'd assume you actually want constant current. At least the most electroplating recipes I've seen specify current density instead of voltage.
You can use something like pic related. For adjustable output you can use a bunch of fixed resistors and a rotary switch. Or a potentiometer, but you'll need a rather big pot to handle non-tiny currents.

>>944964

this is trolling. batteries dont divide their voltage in parallel.

>>944961

a typical LM317-type voltage regulator wont go to 0volts unless you do some voodoo stuff to it; the min is 1.25V. your original idea of a resistor wont work coz it will drop a variable amount of voltage, however a diode is pretty much gonna drop 0.65V under any load, so 1.5V-0.65V = 0.85V. or 3V - 3(0.65V) = 1.0V. so two 1.5V cells in series with 3 diodes should get you very close.

>>944953

So if this has 9v power supply, will the voltage going to each led be 9v?

Also, thanks for taking time out of your day talking to me about this

>>944970

nope. it will 9V (approx) thru a 3.3k resistor to limit the current. this will be pretty dim, so you probably wanna go for 820 ohms instead.

>>944969
This is a good solution thanks a lot.

>>944969
> this is trolling.
Actually, he might just be incredibly stupid.

The point remains: batteries in parallel don't divide their voltage.

>attempting to fix PS3
>pull entire connector off motherboard because i didn't realize the wire was held in by a clip
i've got by so far with just tape/screw terminals but i think it's time i bite the bullet and get a soldering iron

is there anything/a specific model in particular i should be looking for or is any cheapo one fine for a beginner/occasional use?

>>944991
>any cheapo one fine for a beginner/occasional use
this
go look on amazon for whataver's cheap and has good ratings. for electronics go for something in the 30W-60W range with a pencil tip.

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I have a LED strobe 240v UK that flashes on and off.
is it possible to make it fade in or out?

I have googled about and from my pleb understanding the potentiometer controls the rate it takes to fill the capacitor to control the speed the LED flashes at

its a LM358p IC timer I don't really understand the difference what this does in comparison to the popular 555 timer, but I saw a video with a break board that had fading LED

https://www.youtube.com/watch?v=qLAi7hkDuYw

and I'm wondering if I can change a resistor in this set up to make the LED fade on off ??
or is it necessary to change the controller too ?

Im not really too sure what I'm doing and where to learn ...

would there need to be a resistor AFTER the discharge capacitor ?

Any tips or advice would be appreciated !
pic related

>>944991
I prefer the lighter fuel ones as they're hotter faster and cableless but any will do, its more about practice than tools.

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>>944991

you can get a $6 generic iron, like in the pic, which is sold to schools all over, but you can never be sure if your failures are due to the iron or your skills. if you want to eliminate the iron as a source of potential fail, you'd get, at minimum, a Weller WP25 for 3 or 4 times the cost.

that's for electronics. if you're more interested in doing wiring, you'd get the higher power WP35.

>>944949
Look at lm317 solutions for voltage regulation, the lowest you can go is 1.20-1.25V. Then put a Schottky diode in series after the regulator. This will result in 0.2-0.4V voltage drop (depending on current, but then you can adjust lm317 for best results). Keep in mind, that lm317 has dropout voltage as high as [email protected], so for 1.2v you should feed it at least 4V to have some margin.

>>945010
>>945012
>>945013
thanks guys

>>945012
Uhm, I don't think you can do it. 555 is totally diffrerent than what you have inside your device (dual opamp). 555 timer has astable oscillator mode which can be used to generate PWM signal to regulate brightness. There are plenty of schematics, so just make one from scratch.

>>945016
so the 555 is what controls the fade and not the resistor ?

>>945015
don't forget to get soldering stuff with it (solder wire, solder wick, stand, sponge+dish, heatsink clips).

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>>945012

the LM358 is an general purpose op-amp, which can be used as an oscillator, or a million other things. generally, you cant just change a resistor or two and get it to do something else; you have to redo the concept.

the way the dude in the video did it is by using the triangular voltage on pins 2 & 6 of the 555, instead of the usual square wave on pin 3. if you want the same result, you need to follow the video guy's circuit, or some other similar circuit. in other words, you have to change everything.

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>>945014
Had a lm350 laying around and did something similar. See pic related and beware the heatsink that didn't fit the right way because of sloppy work.

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What does /ohm/ think about this device? Is it a worth buy, considering I'm looking for my first oscilloscope? Other features also seem nice, but I'm more interested in it's capabilities as a scope at the moment.

Here you can find more info about it:
http://store.digilentinc.com/analog-discovery-2-100msps-usb-oscilloscope-logic-analyzer-and-variable-power-supply/

>>945074
I wouldn't.
Features are nice, (the power supply is laughable) but I'd suggest you rather get a nice cheap Analog scope.

You can get a good 25MHz one for $50. And you can obviously do better if you get a little bit lucky.
As far as power supplies go, anything under 30V is going to be fairly useless. Brand new lab power supplies with current limiting (important feature) also go for about $50.

And you really won't need a logic analyzer.
Basically, you can get a cheaper and better deal if you buy used individual components.
Thing with used electronics components is, people don't actually beat on them, unless you're buying from a school. And even then it's not nearly as bad as say, buying a $300 car from Craigslist.

>>944971

So suppose I want to keep the LED to indicate the step in the sequence, but remove the resistor and have the output variable between 0 and 5v. Could I use a potentiometer to do this?

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I'm just about to build pic related.

It is a circuit to dimm down cheap chinese after-market daytime running lights for my car. found here: http://www.homemade-circuits.com/2014/04/smart-car-drl-controller-circuit.html

spice simulation looks promising but i'm pretty new to electronics so i thought i'd better have this peer reviewed by you folks.

anything that springs to mind? will i die in a horrible car fire?

>>942919
Hell no solder that bitch

>>945085
The LEDs have to be driven via current-limiting resistors. You need one resistor per LED (unless only one LED will be on at a time, in which case you can use a single resistor).

The current drawn by a LED is roughly a step function. Below the LED's forward voltage (typically ~1.5V for a red LED), it draws practically nothing. Above that voltage, it will draw whatever it can get. So if you don't have a current-limiting resistor, the first time the LED turns on, it will fry.

Similarly, if you use a single resistor, the LED with the lowest forward voltage (there is always some variation between individual LEDs within a batch) will get practically all of the current. The others will be off or almost off.

>>945087
make sure you get a proper enclosure, crimp where possible, use heatshrink, and don't mount anywhere it's hot. If possible, add a fuse to it on the +12V.

>>945087
have you done the math on what those transistors will dissipate?

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>>939562
Buy pic related.

>>945144
>now only $699.99!

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>>945087
Crap circuit overall, and a BC547 isn't big enough for Q3. Also, you should add a load before simulating it so that you can measure power dissipation.

I'd rework the headlight/indicator dimming part so that it just pulls down the base of Q1 in order to dim. Something like
> pastebin.com/5aC2ynWH

Don't take part numbers or values as significant; you'll need to Spice it with your desired output transistor and load.

>>945144
Oh hey, I had one of those as a kid. Dad got it for me when I was 10.

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>>942260
Ok, now I've got a problem, the receiver is noisy, the noise goes from 0 to 5 volts all the time, triggering whatever "one shot" circuit is connected to.
When the transmitter is on, the voltage drops to 0, I need a filter so the "one shot" can disregard all that noise and be triggered when the receiver drops to 0 volts.
I guess the only change between the noise and the signal is the duration of the LOWs, the filter should be able to tell when a LOW signal is longer than those inside the noise and output a LOW pulse accordingly to trigger the one shot.
Any better ideas? I have no idea about filter design.

Recently got into hobby electronics and have only worked with breadboards so far. I want to try my hand at soldering extremely simple circuits.

Do you have any recommendations for perf boards? Are there any especially cheap but reliable sources?

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>>945241
can't give buy recommendations because i get my stuff locally, but if you're not already aware there's a few varieties of boards that get called perfboards. you want either of the bottom kinds in the pic, and the bottom left is best because you can cut traces to be as long as you need them.

>>945259

That helps quite a bit. Do the bottom two have any specific names or will I just have to identify them visually?

>>945289

Are they called stripboards?

>>945289
the bottom left is stripboard or veroboard, the bottom right is called protoboard iirc, the top right is perfboard, and i don't remember the name of the copperless board. generally ebay sellers will call them whatever the fuck they want though, so you'll need to confirm visually.

>>945293

Makes sense. Thanks!

>>945293

your terminology is a bit off: perfboard is the stuff without any copper (i.e. just a perforated board), if you add single copper pads it becomes copper-clad perfboard, if you add strips it becomes a stripboard or veroboard, and if it's laid out like a breadboard, it becomes a solderable breadboard.

>>945085

if you want to keep the LEDs, then you need to keep current-limiting resistors as well. as for pulling out a a pulse between 0 and 5V, you could use a pot by connecting it between ground and the output pin of the chip. if you wanna make sure your pot output never goes over 5V, you can run the circuit from 5V instead of 9V.

File: circuit.png (11KB, 336x344px) Image search: [Google]

11KB, 336x344px

Can anyone help me with recognizing what is this circuit for and how does it work?

>>945420

looks a bit like a current mirror, invented by Flip Wilson.
https://en.wikipedia.org/wiki/Wilson_current_mirror

>>945424
What? How could that work as a current mirror?

>>945180
>a BC547 isn't big enough for Q3

yeah i made a mistake there, Q3 should have also been a tip122.

thank you very very much for your time and effort, helps me a lot.

>>945387
Could I run this on 12v if I wanted that to be the top end rather than 9?

>>945446

yeah, the 555 can handle up to 15V, while the 4015s can handle 18V.

>>945448
Idel. Thanks again

>>945420
It's a differential amplifier (long-tailed pair) with 100% negative feedback.so that it behaves as a current amplifier (buffer) with unity voltage gain.

Spice schematic: pastebin.com/3LKWGP2d