For the variable output, we need some characteristics of the lm317 voltage regulator first. This power supply is rated at 350w and has two 12v rails unlike the mini power supply which had only one 12v rail.
1) i want to make a cheap variable power supply, so i decided to for the lm317 voltage regulator, as it is linear, it has some inherent voltage drop( datasheet says vin must be at least 3v bigger than vout).
Atx variable power supply hack. It outputs a total of 400w and has a regulated. Mod your atx power supply into an adjustable lab power supply! Warning never connect to ac wall plug while cover opened !!!
At the time of making mini atx benchtop power supply mini atx benchtop power supply i had already decided to make a variable benchtop power supply and had ordered parts from online store for it. Want to add a variable voltage output to your supply? Anyway you can hack your smps to raise the output voltage upto 13.8v, or so, but with great care!
It took lot of time for the parts to arrive as i had ordered them from overseas supplier. A lot of people started to ask me for a schematic, however i had to respond that there was no. The basic idea is to find the pin on the regulator that reads back the voltage from the output.
It should go without stating that this will void your warrantee. Save money by converting the cheap atx power supplies that can be found in any discarded computer. I needed a psu (power supply unit) for my electronics projects, so i modified an old atx psu (computers' power supply unit).
In this post we will hack atx power supply to use it as a bench top power supply which can be used for different electronics projects. This project takes a slightly different approach by using a female atx adapter which allows you to plug in any psu into the brick. I have two atx power supply in my lab.
Computer power supplies cost around us$30, but lab power supplies can run you $100 or more! You can salvage from your old desktop computer. To make a good variable power supply from an atx ps, you really need to hack into the pwm control circuit and feedback loop system that regulates the voltage output.
You need one to open the atx power supply casing if you want to mount the breakout board on it. If there is problem at least it is still under warranty. This is my second benchtop power supply.
Always have a look at the connectors to detect which wire is the wanted. Make sure your computer is turned off first! Open up the power supply unit by removing the screws connecting the top and the bottom of the psu case.
Use a multimeter to measure the output voltage. Here’s a fancy way to convert an atx powers supply into a bench supply. Once you have built the circuit test it carefully and measure the output voltage.
Use one of the fixed voltage outputs from the atx ps adapter to power your lm317, whichever voltage is closest to. One is a bit old which i took from my colleague desktop computer:). I came here to ask a few questions, because i know that a lot of guys here already did this kind of thing( did an atx bench psu).
Each laser we use takes up 30 ma (milliamps) of power. Unplug the power cord from the back of the computer. So if you want a device with 100 lasers we need => 30ma * 100 = 3000 ma (aka 3 amps).
The output voltage is defined by this formula: This diy project will give you a power supply that produces a +3.3v, +5v, and +12v current, as well as some practice assembling basic electronics. The colored banana jacks follow the atx color conventions for voltages as follows:
(leave a few inches of wire on the connectors so that you can use them later on for other projects). Some weeks ago i got myself an old unit and decided to hack around and see what happens. The resistors are indicated on the schematic.
I found this implementation very interesting. This is fairly easy using an lm317. Making an atx power supply work at 13.8v has been thoroughly discussed.
This is a real atx to regulated supply conversion, which might come in handy for you. You could build a separate board to run off the atx ps adapter as detailed in the first article below: I used a 10 turn 10k ohm potentiometer i had.
Atx psu hack with regulated variable voltage and lcd voltmeter. Atx power supply with variable output voltage? For this project i am using an old atx power supply which has been salvaged from an dell optiplex desktop.
Now, test your atx power supply first before you hack it. I am using an atx power supply to drive a 12v car audio amplifier. The reason why i have chosen to make this article was the increasing number of popularity of my atx supply hack, which i posted on 4hv.org and simultaneously on youtube in august 2011.
Because i am new here i will give a little background on me i have used the atx supply on many projects including a have made and using a 24v by combining 2 supplies. Vout = 1.25* (1+ (r2/r1)). [tg] didn’t just cut off the motherboard connector and add banana plugs, but improved the functionality.