hi to all well its fairly simple with atx power supply you have yellow wire which is 12 volts the red wire which is 5 volt the blue one is 3.3 volt the balck one 0 volt.. and the green one serve as switch...lets get started .. cut all unnecessary wire leaving only the yellow , black , red and green wires only .. short the green wire to the black one this will start the power supply ...its just to test if all is ok ... now there is a simple electronic circuit that will help in the variation of the voltage..please find the circuit attached...now you can use it from 1.25 to 12 volt without any problem...be carefull a heatsink should be attache to the lm317 cause it comes a pretty hot after some minutes ..be carefull you are dealing with elctricity....any querry please feel free to ask..firstname.lastname@example.org
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I know this is a bit late :) But if you have not managed to find the info yet this just might be the answer. If you have found it then it may be of use to someone else looking for a cheap bench DC PSU.http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply
Well since a tatoo machine generally operates between 6 and 12 volts and a power supply puts out 12 volts.............Now my tattoo power supply(admittedly a cheap one) is rated at 2 amps for output which sounds pretty reasonable to me. I'm not sure what the max is,for a tattoo machine. I also can't remember the amperage a computer power supply puts out. There are a few things to keep in mind though. I will try and help as much as possible though.An ATX power supply doesn't have an on/off switch like an AT power supply does. It's activated by a momentary switch through the motherboard(I'm a computer tech with over 15 years experience BTW as well as electronics engineering). That will be the first hurdle. Secondly in theory you could just hook up a "trim pot" as it was put(which the technical name for it is potentiometer or variable resistor), to vary the voltage, but there in comes the issue of current(amperage). When one part of the circuit remains constant, in this case voltage, and you change another value, in this case resistance, then current will also change. This is applied from eletronics engineering theory called Ohms Law. Which is a VERY simple algebraic formula. Voltage divided by current equals resistance. Or numerically V=I*R or I=V/R. For reference I is current(don't ask me why it's just the way it's written and taught, just like sometimes E is used for voltage which means electromotive force but that's beyond the scope of this reply). So with a constant value(voltage), and a known set of variable values(resistance), you can determine what the minimum and maximum current will be within a given tolerence of error. Of course you will need a scientific calculator for this set to engineering mode, with an accuracy of 2 decimal places, and you will need to know how to read the exponent values. Which you can find out with any basic electronics theory book. If you would like to know these, just write me a message on here and I'll answer you.
Well since power supply for my tattoo machine too a dump on me, and I was intrigued I decided to break out my calculator and do some math.
Now resistance, doesn't just drop voltage it can drop current as well. 12 volts divided by 2 amps gives us 6 ohms of resistance. 12 volts divided by 4 ohms of resistance gives us 3 amps of current. Or 12 volts divided by 4 amps of current gives us 3 ohms of resistance.
So using my tattoo machine power supply as an example for current, 12 volts divided by 2 amps gives us 6 ohms. Now 6 volts at the same amperage would be 3 ohms. Now divide 6 volts by 6 ohms, and you get 1 amp. 6 volts divided by 3 ohms is 2 amps, and so on.
With what we are working with here, it's fairly easy to do it in the head or a regular calculator instead of a fancy one setup for engineering. Now if we were working with milliamps, or k ohms or something, then we'd need the engineering calculator.
I don't mean to try and give a complicated lesson, but since every power supply is different, etc. It's easier to just give you the figures behind it and examples to show you how it's done. Considering the values we are working with the margin for error is negligable really. If you are getting funny looking numbers, then go back to the formula, something likely isn't right with the math. There should be no "remainders" left over after the division or multiplication, only whole numbers.
Speaking of multiplication, remember we can do the inverse of those functional examples I gave. Which might be more helpful to you.
Say you know there are 2 amps of current in the circuit, and you want to know the voltage for a given value of resistance. Lets try it. 2 amps, multiplied by 4 ohms gives us 8 volts.
So as you change your resistance, then your voltage and your current will change, at least in some cases.
The only other thing I can tell you that MIGHT be of help is called Thevinans Theorom(don't kill me for my spelling it's been awhile). Which states simply, the sum of the current going into a circuit is equal to the sum of the current coming out of the circuit. Although it's usually inverse. 5 amps going in -5 amps coming out. What it means though is that, the voltage versus amperage, versus the resistance is all proportionate. It's just something to keep in the back of your mind when doing some of these figures.
Hopefully I have managed to provide you with some kind of starting point without making things too confusing. If you have to ask yourself if I meant this or that, just reread it. Everything I said, is exactly what I meant. No guess work to find out what I mean.
Good luck and let me know what you come up with.
I think a computer power supply has two sets of amperages per 12 volt rails. I think one is about 5 amps, and the other is like 20 amps.
thank you all for your input but yes i really am jst looking for the instructions for converting an atx into a power supply for my tattoo gun,I am already a tattoo artist,and do have a power supply but am trying to find a cheaper way to make a variable speed power supply rather than buying one,i understand the instructions for creating a power unit from the atx power supply,but am wondering if there was someone out there who had made it variable. again thanx for ur input people.
Do read the tattoo gun Instructables - there's a lot of advice attached to themL
frollard is right but also your going to need one of the adjustable knob things (i think they are called trim pots or something) so you can adjust the speed for your machine.
I misunderstood his question - I figured he wanted a 12v source for a 'tattoo machine power supply's input. He literally wants to convert an atx supply into the power needed to run a tattoo gun...theres probably a few sets of instructions out there.
find the power requirements of your tattoo supply, and attach the wires from the computer psu to it. (as required)
Computer power supplies put out 12 volts yellow, 5 volts red, and 3.3 volts blue?. I may be crazy but there may also be -12 volts too. Some psu's require a certain wire to be grounded with a power resistor to tell it that it's turned on.