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Voltage regulator
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You are currently reading a thread in /diy/ - Do It yourself

Thread replies: 77
Thread images: 18
File: 41iwTUhYqWL.jpg (22 KB, 500x262) Image search: [iqdb] [SauceNao] [Google]
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So, i have this cooling pad, and i want to be able to regulate the fan speed, so if you guys could make a circuit, the cooling pad is the Cooler Master Notepal X-Slim.

Thank you,
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>>935074
Well, telling us the type of electricity it takes, its voltage and its amperage would help us out. Without that information I can only guess. I'm assuming its 12 volts DC and draws under an amp so you can probably get by with a simple rheostat.
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>>935074
>so if you guys could make a circuit

Which bit of Do It YOURSELF confused you?

If you want advice on how to learn enough electronics to design & build your own circuit, check out the /ohm/ thread on here.
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>>935075
Nah not 12V thats the 5V from the USB Port.
I checked it up it should be 0.38A, 1.9W at 5V.
Very easily Dimable so, yes, do it yourself!
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>>935074
Pic related is the circuit inside of my Zalman NC-2000.
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>>935079
btw the zalman doesn't run its fans at 100% to prevent over current of the USB port so you might need to experiment with R1 to get the biasing correct.
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>>935079
Shit I messed up the labeling as that was only for reverse engineering purposes, 2SD882 is the correct transistor and VR1 is speed control.
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OP here

>>935077
The value are in this post

>>935076
I will be building the circuit myself, just not designing it, and i'm not thinking of taking an eletronics phd just for this, i can definately visit the /ohm thread but i don't know how they will teach me in a way that i will be able to build the circuit by myself...

Thanks for the answers.
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>>935079
The USB that comes from the power source is the one connecting to the switch right?
MT1 and MT2 are exactly what?

Thank you for the circuit!

>>935081
I want to be able to make the fan run at 100% if necessary, so will i need to take out the r1?
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>>935087
MT1 and MT2 are the Ventilators
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>>935087
The 5v going to the switch is the 5v rail from a USB port, you can omit that switch if you don't want to be able to turn it off and on. The LED is also optional.

MT1 and 2 are the fans, this particular cooler has 2 fans connected in parallel but if your cooler just has one you might need to experiment with the value of R1 if you don't get the adjustability range desired.
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>>935090
Yes, mine only has one fan.

But how do i define the R1?
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>>935094
Stick with 220 ohm for now and try 180 ohm and 240 ohm if needed. 1/4 watt resistors are fine.
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>>935094
Speed control board is to the right.
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>>935096
Ok, thank you

>>935097
Those are some tiny little fans, mine is 200mm, are you sure that the values are the same?

Thank you guys.
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>>935107
Well 2.5 watts (5v 500mA) is the maximum something like this can officially pull from a USB port, so they should be in the same ballpark.

I'm pretty sure this circuit will be suitable, transistor Q1 acts like a variable resistor in series with the fans whilst D2 protects it and C1 helps to "kickstart" the fans when the speed is set low.

This is why R2 is a relatively high value, to prevent the fan from stalling when trying to start up with the speed potentiometer dialed all the way down.

>Those are some tiny little fans
They are small but shift a surprising amount of air, keeps my laptop temperatures below 50C most of the time.
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>>935114
Mind me asking, what sort of hardware are you cooling?

I'll be changing the thermal paste on my laptop (hopefully I'll get the tube this week), and assuming that doesn't solve the slight overheating issue I have, I may have to invest in a cooling pad.
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>>935114
But there's a problem, i'm not counting on opening the cooling pad (it's new so it's under warranty), i was expecting that i could do this just making the circuit and connecting it to the usb port of the cooling pad.
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>>935156
How does your cooling pad get its power? USB port or external power brick?

>>935153
Here is a speccy cap, laptop is from 2008 but idle the processor is 39c and the GPU about 45c. Under load the CPU really doesn't go above 50c with the cooler, without it easily hits 60C.

I would advise caution when removing heatsinks from laptops as the thermalpads can sometimes rip and they cannot be substituted with paste since the gap is too big (around 1mm).

What kind of heating problems are you having? If you can access the exhaust vents from the inside I would make sure it is free of dust as laptops can build up a thick carpet of dust on the inside of the grill after a few years.
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>>935192
Here's a speccy.
Keep in mind that these are idle temperatures with the laptop in 'Quiet Office' power mode.

If I were to switch it to High Performance mode and start doing something that requires a bit more horsepower I'll be hitting the 70°C mark fairly quickly.
I got the laptop in 2011 and back then the temperatures were around the same range as yours. Maxing out at around 55°C under load.

I do keep the laptop dust clean since it's fairly easy to open up.
The heatpipe design seems fairly simple as well.
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>>935153
>>935192
I experienced a overheating and shutting down problem a few years back, turned out to be a thick layer of dust compacted against the inside exhaust radiator of the heatsink blocking airflow.

I was able to clean it without needing to remove the heatsink potentially damaging the thermalpads, since the heatsink assembly was shared between multiple IC's such as the processor with its thermal paste and GPU+Vram that all have individual thermal pads.

However if that is not an option I've used these pads before to replace the torn OEM pads on client laptops. http://www.amazon.co.uk/ARCTIC-Thermal-Pad-1-0-Conductivity/dp/B00UYTTDO6

The actual thickness you require will depend on the laptop, take a ruler and measure it to the nearest 0.5mm. I've found 1mm to be the most common thickness.

What laptop is it? Maybe I could find a service manual and check for you.
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>>935074
Um, we're really not here as your free engineering design team, but what you want is PWM.
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>>935202
The fans inside a humble laptop cooler are unlikely to support PWM. OP needs a series pass method of regulation.
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>>935199
>>935201
As a point of reference, this is a speccy from 2013 at Idle temperatures.
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>>935192
It's powered by USB, i can connect it to the laptop, to any USB port.
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>>935209
hmm it could be paste then if its doing that at idle, but are you 100% sure that nothing is running in the background? If the cpu and gpu share a heatsink it can transfer heat to the other device.
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>>935203
Exactly.

What about using the LM317?
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>>935213
Does that cable go straight to the cooler or is there another connection point between it and the cable?
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>>935214
Well, there is the chance that I've got some garbage running in the background, but for that exact reason I also dual boot with Ubuntu, which produces identical temperatures.

And yes, the heatpipe is shared.
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>>935215
>LM317
That would make the circuit nice and simple but bear in mind that it would not likely be able to bring the fan upto full speed what with its minimum 1.25v voltage drop.

The transistor arrangement as shown >>935079 solves this issue as the transistor selected has a very low saturation voltage of about 0.4v. This means the fan will see 4.6v at full tilt rather than just 3.75v with the LM317.
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>>935222
This is knowledge right here.

But if the max will be 4.6v it will never be at full speed because it is 5v?

I still don't understand how i will connect this when in the circuit the fans are in the middle of the circuit, i don't wanna have to open the cooling pad, i have the usb male and female already.
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>>935222
or an LDO regulator. But you're right, >>935079
would be the best solution.
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>>935225
What about this? A simple Rheostat in series + project box and optional capacitor for kick starting the fan (don't go any higher than 10uF as this violates USB specs).

http://www.ebay.co.uk/itm/5W-Five-Watt-Wirewound-Rheostat-Potentiometer-Variable-Resistor-Pot-Various-/111237848258

The 25 ohm version will be fine.

>LDO regulator
I forgot all about those lol, yes they will be perfect for this and make the circuit much more simpler. Here is the lowest dropout regulator I can find on farnell for a relatively cheap price http://uk.farnell.com/linear-technology/lt3080est-pbf/ic-ldo-reg-adj-1-1a-sot223-3/dp/1663553

Add a 1uF capacitor on the input and 2.2uF on the output to keep it stable. You'll want around a 560k potentiometer to get adjustable 0-5v out.
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>>935249
TO-220 version for ease of soldering http://uk.farnell.com/linear-technology/lt3080et-pbf/ldo-reg-1-1a-0v-to-36v-5to220/dp/2102611
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>>935217
Give the repaste a try then but be careful not to rip the thermalpads.

I recommend this kit if you can source it in your country, comes with all the stuff you need to perform a proper cleanup and repaste. http://www.amazon.co.uk/Arctic-Silver-Ceramique-Arcticlean-Cloth/dp/B003YDUZNC
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It's starting to get confusing to me, i know that there's many different ways to do this, so i want one that is capable to put the fan at max speed if necessary and i don't want to open the cooling pad, i already have the USB connectors.

So, what's the best option?

What about the 555 potentiometer?
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>>935256
>So, what's the best option?
The Rheostat and project box is the simplest option that can go between the power source and coolers power input. >>935249
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>>935262
I'm not just looking for the simplest, for example this circuit >>935079 with time i could easily build this, and i would have fun, if the best option is to have something that is the double of this one, then i don't care i would still do that.

But why is there circuits like the first one, when something like a rheostat does the same?

Thank you for your patience.
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>>935254
I'll keep that in mind.

Unfortunately the kit doesn't ship to my country. I'm getting the thermal paste from a friend anyways, he's replacing a heatsink on his PC and getting a tube of the stuff with it. Hopefully it's some quality stuff.

For cleaning I'll stick with isopropyl alcohol.
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>>935249
>Rheostat
Sounds like unnecessary power dissipation, what about a switching regulator?
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>>935270
The fan being run from a USB port is only going to draw 2.5 watts max, so power dissipation is not an really an issue.

A switching regulator will likely add unnecessary complexity but OP could buy one of those pre-built modules on ebay.
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>>935267
The Rheostat doesn't offer the same amount of control as a regulator but its usually good enough for an application like this.

What about this circuit, you could splice it into an old USB cable. the switch lets you bypass the regulator to obtain the absolute maximum voltage thus speed to the fan.
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>>935268
Alright then. Well good luck with it, I hear coffee filters make for good cheap lint free cloths. Get that CPU die as shiny as possible before applying new paste.
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>>935278
That sounds great, i just didn't understant what is the switch doing, if i trun on the switch, will it give me the 4.65v right away?

What does the RG1 stand's for?

Do i get max speed with 4.65v even if the specs indicating that the fan is 5v?

Thank you so much anon!
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>>935306
Flipping the switch should give you 5V to the fan, full speed.
The switch is there to bypass the entire regulator circuit and with it, the voltage drop you'd get from the regulator.

RG1 is a location label for the linear voltage regulator (LT3080ET). I'm assuming it means Regulator 1.
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>>935306
The switch bypasses the regulator (RG1) and supply's a full 5v to the fan since the regulator alone can only put out 4.65v because of internal limitations. The switch effectively removes the regulator from the circuit.

Think of it as a "max speed" switch. On the flip side if you decide you don't need max fan speed anymore just flip it into the open position and the fan will go back to being speed controlled by the voltage regulator.
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>>935311
>>935314
Uau! That's perfect, it will feel like i have 2 profile's :)

Just for curiosity, why not aplying a regulator that is capable of outputing the 5v?
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>>935320
Well any linear regulator will have what is called a dropout voltage, that is the minimum voltage that can exist between the input and output before regulation fails.

Since the USB port already supply's 5V this leaves not enough voltage headroom for a full 0-5v of adjustable voltage.

The only thing that could do it is a buck-boost switching regulator, but it could also potentially over-current the USB port as it draws more than 500mA to compensate http://www.ebay.co.uk/itm/4-30V-to-1-25-35V-Auto-DC-DC-Boost-Buck-Converter-Solar-Voltage-Regulator-/181924112336

Besides those large capacitors could trip the polyfuse protecting the USB port as they are larger than 10uF which is speced as the maximum allowable on a USB device.
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>>935347
I understand, very well explained, thank you again :D

>>935278
What's the 50% on the VR? And the 10v in the capacitor's? And what's the function of the diode?

Again, thank you all.
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>>935364
>What's the 50% on the VR?
Ignore that, its just what it's currently adjusted to in the schematic and simulation program I use.

>And the 10v in the capacitor's?
That is the max voltage rating of the capacitor, it should always be rated higher than the voltage you intend to use it with. 6.3v capacitors exist too but that is a bit too close to 5v for my liking.

>And what's the function of the diode?
This prevents the output pin from ever being at a higher voltage than the input pin and back feeding into it, this can sometimes happen briefly if you suddenly remove power (turning the computer off for example).

The diode bypasses the regulator in the reverse direction but doesn't do anything in normal circuit operation.
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>>935375
Thank's, i'm already searching to buy te components, witch one of these is the regulator? http://www.digikey.com/product-search/en?keywords=lt3080et

I can see that it has 5 pins, the ref in the diagram that you made is the vcontrol on the pin config right?

Im looking in Ebay too, i have a store here in town where i can try but i doubt that is cheaper...
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>>935401
Both of those are correct, they are just in different lead formations. One stands upright whilst the other is at an angle, I'd personally just choose the cheapest.

YMMV when sourcing parts on ebay, fakes are commonplace on there. You could end up with a regular LM317 that some chink has remarked as LT3080.
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>>935401
Here you go. Pin 1 of the IC is left unconnected and that small orange capacitor labeled "104" is a 100nF ceramic, it is optional and I highly doubt you'll need it since a computer already supply's a stable 5V.

Keep those electrolytic capacitors close to the IC as they are for keeping the regulator stable.
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>>935658
>it is optional and I highly doubt you'll need it since a computer already supply's a stable 5V.
Is it not for eating the ESD emitted by the pot's wiper scratching across its resistance material?
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>>935658
BTW those capacitors don't have to be exactly 2.2uF and 1uF, that is just the minimum the datasheet recommends.

For example if you can get 2x 2.2uF for less cost than buying two separate values then just go with that, as long as the total combined capacitance is under 10uF since this is a USB device.
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>>935201
I've always found that if it's worth going to the bother of getting at the cooling, you might as well replace the pads, paste, and fan while you're in there. Fans are cheap, tearing down laptops is a PITA, and a brand-new fan will usually be quieter than a worn one.
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>>935660
You're on the right track, its more of a problem when the input ripple is high but doesn't do any harm adding it anyway.

If using a metal potentiometer OP should solder a wire from the metal case to the negative rail, this shorts any noise pickup to ground and prevents any output voltage "jumping" as the initial hand contact charges up a small amount of stray capacitance.

I had to do this on an audio amp volume pot as every time I touched it there was a slight "pop" from the speakers.
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>>935663
>>935660
This along with the extra capacitor should prevent any non-ideal real world influences from coupling into the adjust pin.

Since the shaft of the potentiometer is going to be exposed to the outside world I recommenced connecting the case through a resistor to prevent any accidental shorts or current loops.
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>>935663
Forgot pic.
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OP is back, thank you all for the help, can't thank you enough.

>>935658
What's that 104?

>>935668
>>935670
Does this two make the same effect? Wich one is better?
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>>935854
>What's that 104?
>>935658 that small orange thing labeled "104" is a 100nF ceramic capacitor

>Does this two make the same effect? Wich one is better?
Same circuit as >>935658 but is just a way of preventing external noise from coupling into the adjust pin, it will still work without that extra mod.
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>>935854
>What's that 104?
Its optional but the datasheet suggests it for improved performance >>935670
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>>936315
>>936317
Thanks, so, to finalize, i will make this 2 >>935658
>>935668

This last one, i have solder the resistor to the side of the Pot? What if it only has plastic covering it?
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>>936528
>This last one, i have solder the resistor to the side of the Pot? What if it only has plastic covering it?

They are both the same circuit. The resistor on the pot is an optional extra you can apply to >>935658 to help with preventing external noise pickup.

If the pot has a plastic cover then the resistor to pot body mod becomes redundant.
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>>936528
>>936537
To put it into perspective here it is imposed onto the original drawing. If the pot has a plastic shaft then leave it omitted.
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>>936542
>>936537
Uau, thank you for editing the image.

Thank you all, i really appreciate the effort, i promise i will post in this very same thread the result, if not i can make a new one.
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>>935278
I Just forgot, what's the program that you used to make this?

Thank's
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>>936554
Good luck. Remember, the stripe down the side of electrolytic capacitors is the negative lead.

>>936557
"Circuit wizard". I got my copy on the piratebay free of charge ( ;
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>>936559
Sure, that i already knew, as well as circuit wizard, i knew i have seen this type of diagram somewhere, i asked just to find a standard in this type of software.

Just for learning i tried to recreate the circuit, when i pull the switch it's all ok, but without the switch the motor doesn't get lower rpm's, the pot doesn't seem to work.
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>>936584
Forgot image
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>>936584
>>936586
That's because the regulator in the simulator is an LM7805 which is internally a different circuit to the LT3080. It'll work correctly IRL with LT3080.
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>>936833
At least my version of CW doens't have it available, so...

Thanks
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Use an LM7805. They're a cheap variable voltage regulator with diagrams and calculators everywhere.
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>>937148
Did you even read the thread? OP needs to use a low drop out regulator.
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OP is back

Will this potentiometer work? http://www.ebay.com/itm/2PCS-WTH118-1A-2W-560K-ohm-Rotary-Taper-Potentiometer-/291605999651?hash=item43e5127023:g:4IcAAOSwo6lWN5rE

It has that 4th pin, is it there to make this >>935668 ?

The lady in the store didn't have 1uF 10v capacitor, i brought one that's 50v?
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>>935083
>thinking of taking an electronics PhD
>taking an electronics PhD
>electronics PhD
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>>935270
>switching regulator
>on a brushless motor
Thread replies: 77
Thread images: 18
Thread DB ID: 483984



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