on video Making a ATX Bench Power Supply

 Encyclopedia of ATX to Bench Power Supply Conversion

This guide has almost every ATX computer power supply to bench power supply published to date on Instructables ( as of Dec 2014, about 70 unique instructables). It should be interesting to both those who want to do a conversion, and to those interested in the evolution of a popular topic that has been done over and over on the site. Sometimes the new projects had something to add sometimes not so much.

Some of these projects are great, some original and some just so so.

An ATX power supply can deliver different voltages with high currents. The plan is to modify the power supply to make it easier to use it for your electronic projects.

To turn on the power supply we need to connect the green wire to ground to do this we'll use a standard on/off switch. When the power supply is turned on there will be a +5V output on the gray wire, you could use this to turn on a led as a power indicator if you want to.

We also need to attach a small load on the +5V rail to trick the power supply into thinking it is connected to a motherboard. For this we'll use a 5Ohm 10W resistor but anything under 10Ohms will be fine.

The brown wire verifies the 3.3V output is realy 3.3V to do this we need to connect the brown wire to the other orange wires.

To control the variable output we'll use a buck converter that steps down the 12V output to 0.8V to 12V. We'll also replace the trimpot with a multiturn potentiometer to make controlling the voltage easier.

In the image above you'll see the schematic we'll be using to connect all the wires.

Because there are high voltage capacitors inside the power supply we wont open it. To work around this I designed a case that will be mounted to the front of the power supply giving you a place to put all the wires and components. (In my original design the spacing for the mounting of the buck converter wasn't correct but this is fixed in attached version)

To prepare the powersupply cut off all the connectors and sort the cables by colour. Make sure to keep some of the cut off wires as we'll use them in the next step.

I used some heatshrink to keep the wires separate during the building process.

After printing the Front Panel you need to screw in the banana plugs, fuse holders and the potmeter. Also press the switch in the hole and glue the voltmeter in the hole using superglue.

When everything is mounted use some of the cut of wires to solder the sides of the fuse holder to the positive plugs. The wires coming from the power supply are 20AWG. Because the amp capacity for 20AWG wire is anywhere between 5 and 11 amps I put 3 wires in parallel to increase the amp capacity.

Desolder the trimpot from the buck converter and solder some new wires to it. Solder the other side of the wires to the potmeter on the Front Panel.

Also solder the yellow wire of the voltmeter to the buck converter output.

Solder the output of the buck converter to the back of the fuse holder and ground banana plug.

I suggest using a multi-turn potmeter for a more accurate control of the voltage.

Keep 4 ground wires separate and solder the rest of the ground wires to the ground banana plugs.

Use 2 of the 4 wires for the negative input of the buck converter.

Solder 1 of the remaining 2 wires to one pin of the power switch.

Solder 2 of the +12 VDC wires to the input of the buck converter. Solder the red and black wire of the voltmeter to the input of the buck converter.

After soldering the buck converter screw it into the case using two M3 screws.

Solder the green wire to the other pin of the power switch. This way when the switch is turned on the green wire is connected to ground and the power supply will turn on.

To make sure the power supply stays on we need a small load on the +5 VDC output. To do this we need a resistor of 10 Ohms or less with a power rating of atleast 10 Watt.

I placed a resistor into the perfboard and made 2 holes 60mm apart for mounting.

Solder the last ground wire to one side of the resistor and one of the +5 VDC wires to the other side.

Screw the perfboard into the case using two M3 screws.

 Encyclopedia of ATX to Bench Power Supply Conversion

This guide has almost every ATX computer power supply to bench power supply published to date on Instructables ( as of Dec 2014, about 70 unique instructables). It should be interesting to both those who want to do a conversion, and to those interested in the evolution of a popular topic that has been done over and over on the site. Sometimes the new projects had something to add sometimes not so much.

Some of these projects are great, some original and some just so so.

An ATX power supply can deliver different voltages with high currents. The plan is to modify the power supply to make it easier to use it for your electronic projects.

To turn on the power supply we need to connect the green wire to ground to do this we'll use a standard on/off switch. When the power supply is turned on there will be a +5V output on the gray wire, you could use this to turn on a led as a power indicator if you want to.

We also need to attach a small load on the +5V rail to trick the power supply into thinking it is connected to a motherboard. For this we'll use a 5Ohm 10W resistor but anything under 10Ohms will be fine.

The brown wire verifies the 3.3V output is realy 3.3V to do this we need to connect the brown wire to the other orange wires.

To control the variable output we'll use a buck converter that steps down the 12V output to 0.8V to 12V. We'll also replace the trimpot with a multiturn potentiometer to make controlling the voltage easier.

In the image above you'll see the schematic we'll be using to connect all the wires.

Because there are high voltage capacitors inside the power supply we wont open it. To work around this I designed a case that will be mounted to the front of the power supply giving you a place to put all the wires and components. (In my original design the spacing for the mounting of the buck converter wasn't correct but this is fixed in attached version)

To prepare the powersupply cut off all the connectors and sort the cables by colour. Make sure to keep some of the cut off wires as we'll use them in the next step.

I used some heatshrink to keep the wires separate during the building process.

After printing the Front Panel you need to screw in the banana plugs, fuse holders and the potmeter. Also press the switch in the hole and glue the voltmeter in the hole using superglue.

When everything is mounted use some of the cut of wires to solder the sides of the fuse holder to the positive plugs. The wires coming from the power supply are 20AWG. Because the amp capacity for 20AWG wire is anywhere between 5 and 11 amps I put 3 wires in parallel to increase the amp capacity.

Desolder the trimpot from the buck converter and solder some new wires to it. Solder the other side of the wires to the potmeter on the Front Panel.

Also solder the yellow wire of the voltmeter to the buck converter output.

Solder the output of the buck converter to the back of the fuse holder and ground banana plug.

I suggest using a multi-turn potmeter for a more accurate control of the voltage.

Keep 4 ground wires separate and solder the rest of the ground wires to the ground banana plugs.

Use 2 of the 4 wires for the negative input of the buck converter.

Solder 1 of the remaining 2 wires to one pin of the power switch.

Solder 2 of the +12 VDC wires to the input of the buck converter. Solder the red and black wire of the voltmeter to the input of the buck converter.

After soldering the buck converter screw it into the case using two M3 screws.

Solder the green wire to the other pin of the power switch. This way when the switch is turned on the green wire is connected to ground and the power supply will turn on.

To make sure the power supply stays on we need a small load on the +5 VDC output. To do this we need a resistor of 10 Ohms or less with a power rating of atleast 10 Watt.

I placed a resistor into the perfboard and made 2 holes 60mm apart for mounting.

Solder the last ground wire to one side of the resistor and one of the +5 VDC wires to the other side.

Screw the perfboard into the case using two M3 screws.