I fucked myself over. some redneck dude wanted his kenwood t

>>1223555
Start by completely disconnecting what you added. This will at least tell you whether you fucked the radio somehow or it's just something with your circuit interfering with normal operation.

did you test it before working on it? because that sounds a lot like you don't have an antenna plugged into it.

>>1223565
built in antenna bro

>>1223555
>I fucked up
>what happened

Nobody fucking knows.

Nobody will be able to magic their way and see what is wrong unless you post some guts pictures.

This
>>1223574

>>1223574
well the funny thing is that guts pictures wpouldn't tell you anything. it looks eaxtly as it should

>>1223567
the built-in antenna for that model is only for AM and is kind of shitty, which is why you're only getting shitty AM reception. get some speaker wire and do https://www.techwalla.com/articles/how-to-make-a-simple-antenna-to-improve-the-reception-of-an-fm-radio-receiver , see if that fixes it

>>1223579
For some reason the guy never mentioned anything abut it needing an antenna, he just said he plugged it in like he always does and it didn't work like it was supposed to? And he claims he's picked up crazy ass shortwave signals with this thing? I'm not sure it's the antenna but I'll give the article a read once techwalla decides to work

>>1223578
The funny thing is if you could have spotted anything you wouldn't have been asking 4chainz. Post some fucking pictures or fuck off your with your radio fucking lighting.

>>1223555

What antenna do you have connected to the back?

AM internal antennas on these things always sucked

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Hopefully this helps

>>1223574
>>1223578
>>1223589
Meanwhile, some guy sees that there isn't an antenna plugged into the radio and probably solves OP's problem.

It's this kind of idiot-check that these guys come to /diy/ for, and I don't mind it in the least because it adds to my own list of idiot-checks. If you learn from others' mistakes, /diy/ is one hell of a school.

>>1223584
There are all sorts of fun possibilities related to "picking up shortwave" (AM tuner misaligned? an undocumented variant factory-tuned to Japanese FM and then adapted somehow?), but all of them are under the screwed-down plate to the bottom left in >>1223594 . It's a lot more likely that he had a shitty T-antenna in, forgot about it, and is now picking up solely the 100-kilowatt Tijuana specials on AM which he otherwise last listened to in 1978.

>>1223597
>my solution is better than yours
>probably
>idiot check

Because it is ALWAYS the antenna, holy shit what a tough guy

>>1223555
Hope you used a linear reg and filtered it good.

>>1223639
7912 w/ 22uf?

I swear to God if this dolt just didn't use an antenna I will launch myself into the nearest bus going highway speeds. It's going to be an embarrassing phone conversation and I'm probably going to talk down to him inadvertently just because of how silly this is. So before I plug an antenna in, do these Kenwoods 100% always need antennae?

>>1223645
Did you put ceramics on both input and output *right* next to the regulator?

>>1223647
No I didn't but I got the schematic from someone I trusted enough and the two originators of the schematics never ran into issues

>>1223650
You may find its radiating RF. They can do that if not filtered right at the reg.

>>1223651
Ok so this morning my troubleshooting itinerary is:
Put an antenna in,
Try to put filters on the regulator, (code 104 caps ok?)
Rip out the board and put the resistor and diode back in,
Burn the fucking thing,

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>>1223652
>104 caps

Perfect. As close as possible to the regulator so the wires between the two don't radiate. Use ceramics. Monolithics ceramics are fine also.

>>1223574
I did something similar to my cb once.

Anon, the back where the antenae plugs in can be a little week. Thise bitches can be briken for years and wiggle just right they work fine. Bet you wiggled it loose or ripped it off from its case ground without noticing.

i hope OP didn't actually run into traffic this morning

op is still here. just added in some 104's, got correct voltage measurements at test points. still no FM. about to attach an antenna. pray for me.

FOR FUCKS SAKE
IM GETTING A SIGNAL NOW
I JUST THREW SOME LONG ASS SPEAKER WIRE INTO THE BUSHES AND

DID THIS THING SERIOUSLY NOT HAVE A BUILT IN FM ANTENNA

IT DOESN'T LOOK LIKE IT BASED ON PHYSICAL EVIDENCE AND ALSO THE FACT THAT IN THE OWNERS MANUAL IT SAYS THERE'S NO FM ANTENNA

CHRIST

I HAVE TO TELL THIS GUY ON THE PHONE THAT HE'S AN IDIOT AND THAT HE WASTED MY TIME BY COMPLAINING ABOUT NOTHING

IT GLOWS BLUE YOU FUCKER

>>1224115
FM antennas have to be in the 3 meter plus range, so nothing builds them in (can you imagine a 3-meter-wide reciever?)

If you want to be diplomatic about it, take a video of you "setting everything up" (plug power, plug speakers, adjust tuner to the local country or classic rock station, adjust volume, check knob is set to FM, >zoom in on< you plugging the ersatz antenna in) and text it to him as evidence it's working, and hope he picks up on the zoomed in clue

>>1224115
You sound like a moron, seriously expecting a hifi separate to have an in-built antenna. Kek

>>1224118
also
i'll bet that this hick retard had antenna wire going to two extra speakers
plugged into the antenna connector
and thought it was quadrophonic/never noticed that two of them made no noise

>>1224115
>DID THIS THING SERIOUSLY NOT HAVE A BUILT IN FM ANTENNA

like we told you..

Hey guys. I just found out said hick has popped up on other repair technicians radars as a scam artist. I normally service guitar amps/pedals and a few stereo amps and had very little experience with tuners and radios. I am halfway through an EE degree so I have a bit of background here. I observed the schematic closely and noticed that the negative op amp rail had few components attached so I assumed nothing I did would involve the bits I didn't have experience with. Communications is a 3rd year subject after all, I'll cross that bridge when I get there ;)

So, I just made sure my test point measurements were good when initially repairing it and then sent the tuner back. I expect my clients to be at least half as knowledgeable as I am with their own equipment so if a client claims something is wrong, I pay close attention. I am a new repair technician after all, albeit the best rookie in my city. I am going to record the phone call and document everything. Maybe I'll post a censored version here if it proves interesting.


How should I hook up the tuner when I do a proof video? I'm too lazy to unhook my stereo set right now, I've worked on this stereo set for far too long. is there a quick and easy and reliable way to get the unamplified stereo signal amplified? Would a guitar amp work or is there an easier way? Thanks a lot. I appreciate all if you, even the rude guys.

Oops, I'm tired and stoned. I meant tuner in those last sentences.

I need the tuner signal amplified.

>>1224130
The point of a receiver like this is a one-box dangling wires in, usable sound out solution. Involving an external amp just gives him room to make excuses. Show the front tuned to your WPYX or WGNA equivalent to not offend his tender ears, slowly pan the camera to the back which is wired into a bookshelf speaker and your ghetto antenna.

If you don't have a bookshelf speaker, you can use a computer speaker with a cut-off cable, with one line on one of the active pins and the other on the ground pin.

>>1224133
I thought the difference between an FM receiver and a tuner was that one was amplified and one isn't

>>1224135
Oh, right, if it's ACTUALLY a tuner you would want to amplify the output. But a Kenwood KT-7500 is a receiver; standalone tuners are extremely rare to unheard of post-WW2, and anything with direct speaker out posts like on the left side of the back of this is def a receiver.

Also realtalk, I'm putting so much time into this thread because one of them is in my attic, I used it through high school, and you made me realize they're worth like $300. If redneck-kun continues trying to scam you, refund his money and sever while keeping possession, then put the thing on ebay.

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>>1224139
>; standalone tuners are extremely rare to unheard of post-WW2, a


are you talking about pic related or some other kind of tuner? Standalone FM tuners have been available for decades.

>>1224154
yes, and how many people actually bought one? that shit is the late-70s equivalent of our GTX Titans.

>>1224155
>yes, and how many people actually bought one? that shit is the late-70s equivalent of our GTX Titans.

Oh, you meant that they were rare in your experience. I owned one back when I was a stereo nut, as do lots of stereo nuts. You are correct that very few "normal" people would even consider buying one, but your writing ability leaves much to be desired.

>>1223636
Turns out it WAS the (lack of) antenna, dick.

>>1224157
r/iamverysmart

update: I told redneck man that the tuner works fine and I did everything in my power to make it not work. Now he's claiming he was getting a signal but his complaint is that "when you first turn it on the signal needle goes all the way up then goes all the way down" which sorry if I'm mistaken but I had a reel to reel that did the same thing and I just assumed it was the meter doing what meters do?

>>1224285
>"when you first turn it on the signal needle goes all the way up then goes all the way down"

redneck man is a fucking idiot, demand $50 for your time in fixing problems that didn't exist.

either you get $50 or you never get bothered by him again win/win

>>1224287

also if you are feeling nervous about confronting him i can call him and pretend to be your dad or your boss, t. social engineering professional

he's on his way over. I'm going to explain vu meters and inductors in painfully boring detail until he leaves.

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update: he hasn't shown up yet but I asked a friend who works at a local buy/sell/trade/pawn electronics shop and I got some delicious juice.

Anyways, I decided for shits and gigs to see how bad the signal meter spikes. turns out it doesn't even spike, which surprised me because they usually spike. he is literally making up issues.

>>1224118
75 cm dumass.

>>1223646
You should be laughing at no one if you had not thought to connect a fucking antenna you literal waste of fleah. What the fuck are you doing playing with mains level gear anyway child?

>>1224481
What would one expect from an owner who wants blue leds in a classic tuner.

>>1224481
YOU'RE A WASTE OF FLEAH

>>1223555
Not putting RGB LEDs in and letting the owner configure the color.

>>1224154
>The dictionary defines myriad as...
Christ, it's like I'm reading a bad high school essay.

>>1224480
95 before the feed line which needs to be a multiple of the same length, and good luck installing in a location where a 95 cm feed line is sufficient.
so a 95cm wide cable on top of a 190cm long cable, sure sounds like 2.85m to me.

built into the chassis would require a square-meter pizza box made of plastic to not inadvertently shield

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>>1224730
I actually asked him if he wanted that because I have a few pcbs for 12v colour mixers that I printed that would have worked. I printed a bunch from OSH park and shoved one into my korg volca stand. here's a picture where I only had lit up half of it at that point + it was green.

>>1225106
however the guy was pretty set on keeping parts cost low and I obliged. It turns out he wasn't trying to scam me btw, he was just bad at describing issues and he plugged it into a shitty power bar that did weird things to the european plug adapter on it. the euro plug is only 2 prong meanwhile if you buy the american version it's 3 prong I hear. I did confront him about scamming pawn shops and other repair people but he gave me a spiel on me being too valuable to scam which is nice but suspect.

>>1224115
Kek, nobody understands radio anymore

>>1225109
>too valuable to scam

So he admits being a scammer? I'd say you caught him trying to pull his usual shit.

>>1225136
I know...

>>1224139
Fuck you moron. The "T" in KT-7500 stands for tuner, as in stand alone. It's not a receiver. As most 1960-1990 component stereos had stand alone tuners, they are extremely common.

>>1224940
Quarter wave antenna length for Fm is 75cm.

5/8 wave folded dipole 93.75 cm

2.85m for full wave which you must obviously have on your car or draped on the wall right? Only the cool kids have full wave antennas.

Although I've never tried i don't suppose you can fold them without changing the tuning?

Is the internal antenna that thin white wire circling the inside of the radio on pulleys in >>1223594's pic? Because it kind of looks like an actual mechanical cable controlled by the shaft in the middle like a soap-box racer's steering, not an antenna with pulleys to keep it tensioned.

>>1225449
That is dial cord not wire.

Hey since it seems like the problem has been more or less resolved, and there's people in here who know about radio shit- maybe you could give me some input on something that /g/ is being useless about?

>>>/g/61839280

I'm the hipsterbaiting woodbutcher btw and if we can crack this problem, we'll all make a ton of money with what I have in mind.

>>1223555
electromagnetic interference. maybe the wires to the deal you put in it are interfering with the things around it.

>>1223555
create a list of possible causes. test them in order of simplicity. then repeat.

>>1225563
Infetterance*

>>1225449
the "built in antenna" is the short black bar on the back.

>>1225491
That's a really neat idea, albeit a little pointless, but I'd say the easiest way to go would be to play a bunch of different "stations" through handheld/car FM transmitters, and replace all their transmitting antennae with coax going to where a radio receiver antenna would go. Since you're not going to be losing much amplitude, you won't need very powerful transmitters (maybe logic level currents will be fine) and your receiver could have a tiny gain. Chances are it would be cheaper to make the receivers and transmitter all yourself instead of buying them. The main problem is what you'd use to store each different channel's audio, it would have to be a bunch of different tiny MP3 players.

Alternatively, you could wire up a potentiometer to a raspberry pi's analogue pin and store all the music on that/on an external drive and simply write a program to play different albums/playlists for different voltages from the pot. Even make it generate static when you're in between channels. Not quite as cool though.

>>1225635

Yeah, I want to just plug into the antenna on an existing radio and not have to modify the radio or any controls on it at all.

So far I've at least found out that I can create ONE channel and have it play over FM:

>https://www.siriusbackstage.com/install-garage-and-help-desk/93056-how-fm-direct-adapter-fm-modulator-relay-works.html
>Second: FM radio signals travel much better through wire than they do through the air. Connecting the transmitter built inside your Sirius unit directly to your FM radio antenna plug by wire will deliver a far more powerful signal to your FM radio. This will make sure the signal is loud and free from hiss.

Now we just gotta crack the problem of multiplexing that FM modulation down that wire, and then what media controller drives the pre-made playlists for each station, and I'm halfway to being able to listen to the various stations in GTA 3, San Andreas, 4, and 5 while I drive down the road.

>>1225652
Would less invasive modifications be acceptable? You could, for instance, attach opaque vanes to the dial cord to be read by photointerrupters to detect the active frequency and switch the FM transmitter and playlist to match. If it's a superheterodyne set, you could attempt to sense and count the local oscillator frequency, which in modern sets is 10.7MHz below (or, iirc rarely, above) the tuned frequency, then set your FM transmitter's frequency and playlist to match.
In either case, you'll need an accurately tunable transmitter. The easiest way to do this would be such as the SiLabs Si471x series of FM transmitters, that take L/R in and give FM out, can be digitally controlled, need only two external components, and need no alignment. They're about $14 each in singles and are in very small packages that will need to be reflowed, but maybe there are breakout boards or other chink shit you could modify.

>>1225658

This has to be something that can be plugged into any FM radio.

http://ezinearticles.com/?How-an-Antenna-Diplexer-Allows-for-Multiple-Broadcasts-on-One-Transmitter&id=7707751

Now if that can be used with the FM radio over wire, I'm 3/4 of the way there. Course, looks like I'll still need multiple little transmission chips, but that's still less clunky than lots of separate independent transmitters

>>1225660
There's no reason those chips couldn't be used over wire, but I think you'd want to couple them with something other than a hard wire, maybe a small transformer. You'll probably also want to shield the hell out of it to keep from upsetting any neighbors who might want to listen to official broadcast crap.
If it has to work with any radio, then multiple transmitters and multiple players it shall be.

You all pussies, just get a dollar shop pocket radio and put it in there, it will work without antenna and no one will notice

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the design so far

>>1225662
>I think you'd want to couple them with something other than a hard wire, maybe a small transformer. You'll probably also want to shield the hell out of it to keep from upsetting any neighbors who might want to listen to official broadcast crap.

Yeah, that's the reason for going over wire, that and the elegance of it all. Why be worried about interference when you can just hardwire it?

>>1225669
>thinks the hard wire isn't going to act as a quite effective antenna all by itself
You should attenuate it near the transmitters just to keep it from a) spraying RF everywhere and b) overloading your receiver. That hard wire will make a highly effective transmitter. FM receivers are exquisitely sensitive, not just your own, but other people's too.
Oh, also, you'll need a very clean linear power supply for each transmitter, such as an AM1117-3.3, and each of these transmitters will need to be tuned, the Si471x via a digital protocol that you'd probably have to add in a microcontroller to set up. If you don't need to tune the transmitters all that precisely on demand (and you're using a dial radio, so no?), there are much cheaper chips available that can be tuned with a trim pot on board, but may require a few more external components. You'd definitely do well to search around for FM transmitter ICs and find one that works for your levels of skill, precision, price, and bother.

>>1225652
>>1225668
Why would you multiplex it? Since each channel will be at a different frequency band, there won't be any overlap. Besides, you can't easily multiplex an audio signal with 5 others and not expect a loss in quality, and it would have to be at least 200MHz. Furthermore, there's no point in multiplexing all the channels at once if you'll only be listening to one at a time, it's just wasteful.

>>1225669
Your wires will act like aerials, which is why you should make sure to use coaxial or some other sort of individually screened cable

>>1225675
Yes, adding a gain knob at the receiver is probably a great idea, though if you're smart enough to not just buy 5 car FM transmitters you'll make ones that have a particularly low amplitude in the first place. But put a gain resistor in regardless.

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>>1225675
>>1225678

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>>1225681
If you're referring to time-division multiplexing then you simply don't need it. But if you're referring to the frequency division multiplexing that makes up a selection of FM signals, then isn't that already handled by the low power transmitters themselves? Provided they have enough frequencies to share between them, of course. You might have a little difficulty simply hooking the output of each FM-encoder/mini transmitter all up in parallel, so you might want to put buffers after each one to stop the signal from feeding back into them.

Chances are you can get away with a few FM-encoders without worrying about amplifying their signals at all, and probably less expensive ones than Si471xs. I found one on Mouser for little more than $2, and there's bound to be a model on AliExpress, or even something simple like pic related.

>>1225681
Is that the passing car whose driver gets inspired to run down kids for points?

>>1225703
>comes with a free ultra miniature fingerbox
SOLD

>>1225704
You mean that can? it's actually an electret mic with felt on top.

>>1225707
Nah, pull the slug from the coil and go to town.

>>1225491
What are the sound sources that you will be using ? Sound cart output, or random analog one like from a mp3 player

>t. guy that asked you if AM was OK on /g thread

If you're planning to use a sound card, look for a program that generates a baseband AM signal on the line out port, 8kHz wide, then make a small transceiver so it goes to your receiver's AM band.

Once you got it, look if you can manage to add another channel on the same line out port, but on the 9kHz-17kHz, so it will appear just next the first one on your receiver after transceiver operation.

Then repeat the process with as many port you have on your sound card, a typical 5.1 have 6 ports, hence either 6 or 12 AM channels depending on how you build your transceivers.

>>1225703
>mfw <1$ FM transceiver
or go with a pack of 10 FM transceivers, but don't expect quality because of that ONE transistor design

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>>1225741
They're literally a common emitter amplifier and what I think is a tank circuit, doesn't that make this AM instead? Or is the frequency of the tank circuit modulated by the output of the oscillator? deceptively simple, but pretty dirty. If you want to lock accurately onto a frequency you'll have to go digital. Pic is from the "build your own" model, by the way.

>>1225763
It produces a combination of AM (which gets removed by the receiver) and FM. The transistor's junctions act like parasitic varicap diodes so that the effective capacitance in parallel with the coil varies with audio input.

>>1225109
>he gave me a spiel on me being too valuable to scam
what are you retarded?

>>1225741
>What are the sound sources that you will be using

192kbs stereo audio or comparable. Guess that means if I want 5 separate stereo streams, the easiest off the shelf hardware would be two 5.1 soundcards and just remap all ten channels to five stereo pairs, forgetting the two subwoofer channels. They also have SPDIF outs usually so that could also be used to run the data to the transmitter, just need a decoder in the mix.

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How's this looking now? I'm aware we have passed peak autism

>>1225934
>change them around
Why? Just set and forget, and mess with their trimmer caps/pots if you have to change them, no point in defining them with software unless you really want to buy prebuilt transmitters.

I think the wizard is a collection of buffer amplifiers, and maybe an isolation transformer and/or volume potentiometer too.

The multiple sound card thing will be a pain to get working, but it's probably the only way of doing it besides having 5 mp3 players with their storage chip replaced with bodge wires to some sort of processor. Maybe getting 5 of those tiny USB sound cards and somehow programming them to use different audio channels might work, though that might be more difficult than programming different stereo files to play on different channels.

>>1225934
>a passing wizard magics this into working
If your low power transmitters have their own antennas, you could stick an aerial inside the metal box housing all that crap, aka strip off a few inches of the shielding and jam it in. If not, use very smol capacitors, on the order of a few pF.
Otherwise, block diagram looks about right I suppose.
If you don't feel like getting too deep into the RF, try a few http://www.dx.com/p/usb-fm-transmitter-100471 (will need modifications to set frequencies)

>>1226119
USB-to-audio adapters are little more than breakout boards (e.g. the PCM2706/2707 datasheet). Anon could include a USB hub onboard with five USB stereo DACs. A rasPi could start up an mpd or mplayer instance on each of the DACs according to its bus position.

>>1226136
>USB hub
Would its multiplexing be fast enough to not notice a drop in quality? I think pi-style computers run at a half-dozen hundred MHz.

Now couldn't you use the raspi itself to generate the FM signal, or would that be more difficult?

>>1226119
>>change them around
>Why?

Good point, I like the idea of being able to set what frequency each station is on though, but it doesn't have to exist in version 1.0, plus that's extra shit to have to control in software


>The multiple sound card thing will be a pain to get working, but it's probably the only way of doing it besides having 5 mp3 players with their storage chip replaced with bodge wires to some sort of processor.

That's.. actually an idea, I mean, who says you can't have 5 mp3 players running off one storage device? But it's kludgey and controlling it sounds like ass. Making something basically divvy up stereo sound streams over a couple soundcard channels is at least something that'll have some precedent

>>1226152
>Now couldn't you use the raspi itself to generate the FM signal, or would that be more difficult?

pitx and pifm

https://github.com/F5OEO/rpitx

http://hackaday.com/2014/06/15/easily-turn-your-raspberry-pi-into-an-fm-transmitter/

>"The Pi outputs a square wave, which has harmonics all the way up to daylight. So it’s not just putting out energy at the FM frequency, it’s also nuking multiple different frequencies all the way up the spectrum. That’s pretty impolite behaviour (not to mention illegal, even though it’s unintended), and it’s why you should be putting a filter on the output – that absorbs any and all spurious harmonics that are outside the band you’re intending to transmit on."

>>1226157

also the more I read on this the more it seems using a pi for fm transmission is more of a hobbyist "did it because i can" than a "that's nice quality" thing. apparently audio quality is low

>>1226158
Right, just wondering. Using a dedicated chip (or USB breakout) is probably the way to go.

Checking aliexpress for FM transmitter boards, some of this stuff is kinda funny, this guy seems to just be copying circuits from an old b&w TV and admitting that it may be dodgy:

https://www.aliexpress.com/item/FM-FM-transmitter-MP3-wireless-microphone-transmitter-radio-transmitter-board-KIT-Parts-module/32812243965.html?spm=2114.search0104.3.42.herSAM&ws_ab_test=searchweb0_0,searchweb201602_4_10152_10065_10151_10068_10130_5400011_5430020_10307_10137_10060_10155_10154_5370011_10056_10055_10054_10059_100031_10099_5410011_10103_10102_10052_10053_10142_10107_10050_10051_5380020_10084_10083_10119_10080_10082_10081_10178_10110_10111_10112_5390011_10113_10114_10312_10313_10314_10315_10316_10078_10079_10073_10120_5420011_9131-9131_10120,searchweb201603_16,ppcSwitch_5&btsid=6aac8a00-7d5f-4e41-ab6e-38aa4c238bc2&algo_expid=117f8415-c5d8-47bd-8f8a-1870ddfb9efd-5&algo_pvid=117f8415-c5d8-47bd-8f8a-1870ddfb9efd&transAbTest=ae803_3

>Highlights 1 this circuit uses the old black and white television local oscillator circuit, the stability of how good it is not to say, only played black and white TV friends know.
>Highlights >(2) this circuit is not very high on the power requirements, you can use the phone universal charge, power supply and other power supply voltage, and finally bid farewell to the only battery defects.
>Highlights (3) of the circuit, the circuit board can touch the antenna can also be held in the hands (touch part may be interfered by high frequency oscillation, let go and still work properly), no matter how you feel, how mobile can be completely solved, can not move.
>Highlights (4) sound quality can also meet the requirements of play.

>>1226163
You know you can just post the link up to the
>.html
part, right?

https://www.aliexpress.com/item/Stereo-FM-Transmitter-Module-Phase-locked-Loop-Digital-Wireless-radio-Module-MCU/32278613960.html

>-Working frquent:76-108 MHz
for when you really want to be raided by the FCC

>>1226165
Whoops

I'll try my hand at making one of these transmitter circuits once I've made receiver.
>watched "children who chase lost voices"
>now I want to make a cat's-whisker radio

>>1226152
USB works on 1ms frames. If you use a high-speed hub with multiple transaction translators, such as Microchip USB2517, you shouldn't have a problem. Each DAC expects to reserve about 2Mbps of the available full-speed bandwidth. With its own TT on each downstream port, it can have as much as it likes. With a high-speed upstream, you shouldn't even come close to running out of bandwidth. Routing high speed USB is a little bit critical, what with impedance specs, trace length matching, and so on. Nothing KiCAD can't do.

Okay now time to find some out of the box solution for the multiple streams:

https://www.raspberrypi.org/forums/viewtopic.php?t=79034

Also, the multiple stereo outputs:

https://superuser.com/questions/745731/turn-5-1-or-7-1-sound-card-into-34-distinct-stereo-outputs

https://wiki.archlinux.org/index.php/PulseAudio/Examples#Splitting_7.1_into_5.1.2B2.0

https://askubuntu.com/questions/177800/how-to-redirect-single-audio-channels-to-different-devices

https://help.ubuntu.com/community/What%20is%20JACK

Or, yeah, could use multiple USB stereo dongles

Rasp Pi seems not be able to handle more than 2 stereo streams before bogging down.

http://icecast.org/

>Each Icecast server can house multiple broadcasts (or mountpoints) each containing a separate stream of content. A ‘mountpoint’ is a unique name on your server identifying a particular stream - it looks like a filename, such as ‘/stream.ogg’. A listener can only listen to a single mountpoint at a time. This means you can have a single Icecast server contain either multiple broadcasts with different content, or possibly the same broadcast but with streams of different bitrates or qualities. In this case each broadcast or stream is a separate mountpoint.

https://www.raspberrypi.org/forums/viewtopic.php?t=79034

>I'm using Darkice. I built it using the instructions here: http://www.t3node.com/blog/live-streami ... pberry-pi/
Darkice can feed eight concurrent Icecast streams on my Linux PCs, but the Pi starts to stutter when I try more than two.

>>1226190
>decoding and reencoding a stream
>to be re-decoded and played
Why? Wrong technology.
I have an Orange Pi Zero (quad-core 1.2GHz Allwinner H2+) at hand. I just simultaneously uncompressed five songs to /dev/null, 4m31s to 6m35s in length, 25m37s in total, using the mpg123 command-line player.
[code]
real 0m18.872s
user 1m2.155s
sys 0m1.075s
[/code]
Even if sys time becomes equal to user time, CPU will not be a limiting factor.

>>1226196
>>decoding and reencoding a stream
>>to be re-decoded and played

I'd push the stream straight to the FM modules via the sound sinks but I need some way to manage the streams, icecast is the only off the shelf method

>>1226205
Why do you need to manage streams at all? Aren't you just playing a playlist? Nearly any command-line player can do that much.

>>1226205
>>1226214
If you do need to edit playlists and control them on the fly, there's a program called mpd that basically manages playlists, decodes the files in sequence, and pushes them down a sink, while providing a user interface plugin architecture to stop/start/edit/change/etc. Just run five instances of that, each associated with its appropriate DAC.

https://www.amazon.com/Scosche-Audio-FM-Modulator-Universal/dp/B0007THIDQ

Not going to use these- but am I correct that these devices are just pretty much the same as

https://www.aliexpress.com/item/Stereo-FM-Transmitter-Module-Phase-locked-Loop-Digital-Wireless-radio-Module-MCU/32278613960.html

But with a nice box and wires and limited to two frequencies?

>>1226171
>1ms frames
That sounds like something on the order of kHz, or am I interpreting this wrong?

>>1226281
Correct, 1kHz.

>>1226331
If that's the speed that it switches, then I find it hard to believe that you can get 20kHz signals through without losing data. Shouldn't you need to use at least 40kHz, and that's for some shitty quality?

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>>1226333
No, no. A frame, which is the period of time that a USB host controller divides among downstream devices, is 1ms long.
Transactions with downstream devices can take up varying amounts of that frame. Audio and similar devices reserve some fixed amount of that time in (iirc) their descriptors for "isochronous" data transfer. enough to last them a whole frame. USB 2.0's transaction translators offload the high-to-full speed conversion onto the hub, vaguely similar to command queuing in SCSI/ATA.

>>1226339
>"isochronous" data transfer. enough to last them a whole frame.
That makes a lot of sense, though it does mean you could get up to 1ms latency for some critical things. I wonder if that's enough to turn hardcore gamers away from plugging their mouse and keyboard into a USB hub?

>>1226386
True. USB is not a good choice for host-controlled bit-banging, but it's pretty easy to design a device that does all that waveform generation and/or data capture for you upon higher-level command. If I remember correctly, one of the enhanced FTDI chips would output sequences at a programmed rate.
In any case, USB devices are expected to respond immediately to host requests with an acknowledgement and possibly data, a non-acknowledgement, or a protocol exception. Where TTs are used, the transaction is split into a start part and a completion part, between which the host controller may service other devices or TTs. Transactions don't get stretched across frames.
1ms latency is imperceptible for human input devices and would be swamped by jitter elsewhere in the system, but pro audio guys get even more butthurt about latency than /g/.

>>1226396
>pro audio guys
>digital
Is 1ms too much for their high bitrates? I guess USB3 helps with that.

>>1223555
Look at all this extra work. What did you quote this guy so we can all laugh at your misfortune?

>>1226386

What about using hardwired 3.0 hubs like this:

https://www.amazon.com/ORICO-Superspeed-Expansion-Controller-Connector/dp/B01MRXOKBT/

>>1226167
>for when you really want to be raided by the FCC
for when you want to use it in Japan
or when you want to risk FCC mad to pick up the signal on channels 5/6 on an analog TV set

>>1226422
It's not bitrates pro audio guys worry about, it's latency as such. Music starts to sound loose when some instruments are offset by several ms from the rest, which is also why conductors provide sight cues to the orchestra.

>>1226581
That requires a PC, which may or may not be part of the design is a raspi is enough to do what OP wants.

>>1224120
I've seen people do this.

They'll hook up speakers to the antenna ports of an old receiver because 'Well where else do the other 2 speakers go?'

These are people that are usually too young to remember (or too dumb to remember) the days before '5.1 surround' and shit.

An entry-level Tx-capable SDR should be able to get you a decent number of FM channels, but may be beyond your skill level.

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op here. is a KX 1003 tape deck and a KX 1030 tape dech basically the same thing/? manuals are being listed as interchangeable on websites

>>1225934
MAXIMUM AUTISM OVERLOAD!!!

Looks sweet.

>>1226567
got 40$, not mad.

>>1226876
I thought SDRs deliberately avoided FM frequencies, because they're not on any of the receivers at websdr.org. I assumed it was a copyright thing, but is it? The University of Twente's wide-band reception is pretty incredible, but it only goes up to 30MHz, so if someone made one that could go to 300MHz that would be really neat. Since rtf-sdr.com sell 88-108MHz blockers to remove the high amplitude FM signals, I guess it's for interference reasons that it's blocked?

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>>1226896
FORTY DOLLARS? I'VE MADE SEVERAL HUNDRED WHILE POSTING IN HERE OVER A FEW DAYS.

>MIND FUCKING BLOWN

WOW

>>1226896
>$40
Might be worth it just for the story.

>>1225763
that is a common base amplifier
it also works pretty poorly without an output buffer, because anything in the proximity of the antenna affects the resonant frequency

>>1226896
Wouldn't even cover the gas for my truck back and forth. Your some sort of NEET or something?

>>1227121
ur car fuckin sucks drive a motorcycle, 6-7$ a week in gas

no I do like 5-6 of these projects a week but normally I do amps and pedals. I'm putting LEDs in there how expensive could it be lol

So what should we call the multi radio signal emulator/modulator system?

If dubs I'll call it Clownfart

>>1229036

Whew

>>1229036
The Memeplexer

>>1227121
What kind of shit tier truck doesn't get at least 25 MPG highway in this day and age? Are you driving a 61 Chevy or something or just have a tiny dick?

>>1229116

this

>>1225923
>192kbs stereo audio or comparable
That will be something like a 24Hz large base-signal when the maximum allowed channel bandwidth (whose receivers are designed for) is 8 kHz.
You should consider sticking to 4kHz baseband signals, hence 32kbps mono ones : coding a stereo signal is far beyond the actual point.

>>1230621

i made myself a little sub board to pursue development of the memeplexer mk 1 clownfart

>http://www.salvaged.tech/fm/

the domain itself is going to be a google maps enabled swap meet for old technology / electronics... eventually.
not an imageboard forever. but it'll do for now.

>>1230621

also i just assumed the 192kbs audio gets pushed through the fm transmitter and turned into whatever sausage it wants to grind it into

>>1229116

Rolling for this

>>1230999
W O W
O
W

>>1224115
>not testing shit before you fuck with it
>getting mad when shit doesn't work

Seriously man go kill youself

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>>1230647
>>http://www.salvaged.tech/fm/
>picrelated.jpg
Contribooting

>>1231932

Thanks

The memeplexer will live on as one of /diy/s creations. Done not because we should, but because we could.

It is possible that the LED is producing AM radio frequencies.

>>1230647
Sooo, how is this project going ?

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>>1235453

Found that I already have half the components I need for this in the boxes of shit I bought from a closing down Radioshack

BTW if you guys need any form of adapter or RCA / A/V / 1/4" / 1/8" cabling, I probably have it and I'll sell this shit at a discount