A bench power supply is an extremely handy bit of kit to have around for electronics hobbyists, but they can be expensive when purchased new. If you have an old computer ATX PSU lying around, you can give it new life as a bench power supply. Here's how.
Like most computer components, power supply units (PSUs) get outdated. When you upgrade, you may find you no longer have the right connectors - or that your shiny new graphics card requires far more power than your puny old PSU can handle - a dual GPU setup can easily rack up 1,000 watts. And, if you're anything like me, you have a stash of old PSUs hoarded away in a cupboard somewhere. Now's your chance to use one of them.
A bench PSU is basically just a way of providing a variety of different voltages for test purposes - perfect for those us who are constantly playing with Arduinos and LED strips. Conveniently, that's exactly what a computer power supply does too - only with a lot of different connectors and coloured wires.
Today, we're going to strip the PSU to its bare essentials, then add some helpful sockets onto the case that we can plug projects into.
Warning
Ordinarily, you'd never open a power supply unit. Even when the power is off, there are large capacitors that can store lethal electric current for weeks, sometimes months, after being turned on. Take extreme care when working with a power supply unit and ensure it's been dormant for at least three months before opening the case, or make sure you're wearing heavy rigging gloves when poking around in there. Proceed with caution.
Also, note that this will irrevocably damage the PSU, so you won't ever be able to use it in a computer again.
Components Needed
Two 2.1mm barrel jack and socket - I'll be powering the Arduino directly with this. Two barrel jack plugs will be used to make a male-male power cable.
Variety of 2mm coloured sockets, such as this one (can be used with banana plugs). You may prefer terminal posts.
Heat shrink tubing, 13mm x 1m (and smaller, if you can afford to buy more).
SPST (single pole single throw) rocker switch. I used an illuminated one to serve the dual function as power on light too.
10w 10 Ohm wire wound resistor.
Construction
Unscrew and remove the top half of the power supply case. You may need to pull a plug out of the main circuitry to fully separate the covers.
Next, bunch them with cable ties according to colour, just to make things a little more organised. As a general rule:
Black: Ground
Red: + 5V
Yellow: +12V
Orange: +3.3V
White: -5V
Blue: -12V
Purple: +5V standby (not used)
Grey: power on indicator
Green: ON/OFF switch
A bench power supply is an extremely handy bit of kit to have around for electronics hobbyists, but they can be expensive when purchased new. If you have an old computer ATX PSU lying around, you can give it new life as a bench power supply. Here's how.
Like most computer components, power supply units (PSUs) get outdated. When you upgrade, you may find you no longer have the right connectors - or that your shiny new graphics card requires far more power than your puny old PSU can handle - a dual GPU setup can easily rack up 1,000 watts. And, if you're anything like me, you have a stash of old PSUs hoarded away in a cupboard somewhere. Now's your chance to use one of them.
A bench PSU is basically just a way of providing a variety of different voltages for test purposes - perfect for those us who are constantly playing with Arduinos and LED strips. Conveniently, that's exactly what a computer power supply does too - only with a lot of different connectors and coloured wires.
Today, we're going to strip the PSU to its bare essentials, then add some helpful sockets onto the case that we can plug projects into.
Warning
Ordinarily, you'd never open a power supply unit. Even when the power is off, there are large capacitors that can store lethal electric current for weeks, sometimes months, after being turned on. Take extreme care when working with a power supply unit and ensure it's been dormant for at least three months before opening the case, or make sure you're wearing heavy rigging gloves when poking around in there. Proceed with caution.
Also, note that this will irrevocably damage the PSU, so you won't ever be able to use it in a computer again.
Components Needed
Two 2.1mm barrel jack and socket - I'll be powering the Arduino directly with this. Two barrel jack plugs will be used to make a male-male power cable.
Variety of 2mm coloured sockets, such as this one (can be used with banana plugs). You may prefer terminal posts.
Heat shrink tubing, 13mm x 1m (and smaller, if you can afford to buy more).
SPST (single pole single throw) rocker switch. I used an illuminated one to serve the dual function as power on light too.
10w 10 Ohm wire wound resistor.
Construction
Unscrew and remove the top half of the power supply case. You may need to pull a plug out of the main circuitry to fully separate the covers.
Next, bunch them with cable ties according to colour, just to make things a little more organised. As a general rule:
Black: Ground
Red: + 5V
Yellow: +12V
Orange: +3.3V
White: -5V
Blue: -12V
Purple: +5V standby (not used)
Grey: power on indicator
Green: ON/OFF switch
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