Laboratory power supply from a computer's ATX unit

If you have an old computer power supply (ATX) at home, then you should not throw it away. After all, it can make an excellent power supply for home or laboratory purposes. Refinement will require a minimum and at the end you will get an almost universal power source with a number of fixed voltages.
Laboratory power supply from the computer BP
Computer power supplies have a high load capacity, high stabilization and short-circuit protection.
Laboratory power supply from a computer power supply unit
I took such a unit. Everyone has such a label with a number of output voltages and maximum load current. Basic voltage for continuous operation 3.3 V; 5 V; 12 V. There are more outputs that can be used for a small current, this is minus 5 V and minus 12 V.You can also get the voltage difference: for example, if you connect in to "+5" and "+12", then you get a voltage of 7 V. If you connect to "+3.3" and "+5", you will get 1, 7 V. And so on ... So the line of voltages is much more than it might seem from time to time.

Pinout of computer power supply outputs

Laboratory power supply from a computer power supply unit
The color standard is, in principle, one. And this scheme of color connections for 99 percent will suit you. Maybe something will be added or removed, but of course everything is not critical.

Alteration has begun

What do we need?
  • - Screw terminals.
  • - Resistors 10 W and 10 Ohms (you can try 20 Ohms). We will use the composite of two pentavat resistors.
  • - Heat shrink tubing.
  • - A pair of LEDs with damping resistors 330 Ohm.
  • - Switches. One for the network, the second for management
Details for rebuilding the blockDetails for rebuilding the blockDetails for rebuilding the blockDetails for reworking the blockDetails for rebuilding the unit

Computer power supply completion scheme

Laboratory power source from the computer BP
It's all simple, so do not be afraid. The first thing to do is to disassemble and connect the wires by color. Then, according to the scheme to connect the LEDs. The first one on the left will indicate the presence of power at the output after switching on. And the second one on the right will always light up while the mains voltage is present on the unit. Connect the switch. It will start the main circuit by shorting the green wire to the common one. And turn off the unit when it opens. Also, depending on the brand of the unit, you need to hang a load resistor 5-20 ohms between the common output and plus five volts, otherwise the unit may not start due to built-in protection. Also, if it does not work, be ready to hang up such resistors for all voltages: “+3.3”, “+12”. But usually one resistor is enough to output 5 volts.

Let's start

Remove the top cover of the case. We bite the power connectors that go to the motherboard of the computer and other devices. Unravel the wires by color. Drill holes in the rear wall under the terminals.For accuracy, we first go through a thin drill and then thicker under the size of the terminal. Be careful, do not put metal chips on the power supply board.
Laboratory power supply from a computer power supply unit
Insert the terminals and tighten them.
Laboratory power supply from the computer power supply unit
Add up the black wires, it will be common, and we clean. Then tinned with a soldering iron, dress shrink tube. We solder to the terminal and put the phone on the solder - blown with a heat gun.
Laboratory power supply from the computer power supply unit
So we do it with all the wires. Which do not plan to use - bite off the root of the board. Also we drill holes on the toggle switch and LEDs.
Laboratory power supply from the computer power supply unit
Install and fix the LEDs with hot glue. Solder the scheme.
Laboratory power supply from a computer power supply unit
We place the load resistors on the circuit board and fasten with screws. Close the cover.Turn on and check your new laboratory power supply.
Laboratory power supply from the computer BP
It's not superfluous to measure the output voltage at the output of each terminal. To be sure that your old power supply is fully functional and the output voltages have not gone beyond the permissible limits.
Laboratory power supply from a computer power supply unit
As you can see, I used two switches - one is in the circuit, and it starts the operation of the unit. And the second one, which is bigger, bipolar, commutes an input voltage of 220 V to the input of the unit. You can not put it. So friends, collect your block and use it for health.

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