YAABPS: Yet Another ATX Bench Power Supply

thingiverse

WIP This is a bench power supply I'm designing that uses an PC ATX power supply. The general electrical setup uses a break-out board with an 24-pin ATX 12V connector. The 12V line is attached to a boost converter to bring it up to 30V and then a buck converter with a knob accessible outside the enclosure to bring the voltage back down to the desired level. Power is provided at several banana plugs on the front of the enclosure. A 10A circuit breaker is used to give some level of protection but inline fuses probably wouldn't be a bad plan to prevent burning your house down. A 12V case fan is mounted in the lid to pull air out of the enclosure. Vents are positioned to ensure that fresh air passes across the heat sinks on the boost and buck converters. I goofed and didn't read the product description closely enough to see that the V/A meter I designed it around only works down to about 6.5V. To get around this, I included several extra plugs to provide access to the the ATX 3.3V and 5V rails. These won't be wired through the larger since it won't even turn on below ~6.5V. Toggle switches are used to turn on/off individual rails. There is also a version of the bottom to use a smaller digital volt/ammeter that works down to 0V but is limited to 10A. The only major issues I've found with the electronics (so far) is that the buck converter provides ~1v even when it is turned "off". Also, keep in mind that the larger meter won't even power up until the adjustable voltage is at least ~6.5V. If you want to measure voltage/current below that, you'll need to use the smaller meter or plug an external multimeter in. Parts list: * [ATX PSU break-out board](https://www.amazon.com/gp/product/B01NBU2C64) * [10A circuit breakers](https://www.amazon.com/gp/product/B081PFZWFX) * [Boost converter](https://www.amazon.com/gp/product/B08246FB95) * [Buck converter](https://www.amazon.com/gp/product/B071KBQMDR) * [Power switch](https://www.amazon.com/gp/product/B074LZN29Z) * [Banana plugs](https://www.amazon.com/gp/product/B07D52R7TL) * [SPDT Toggle Switches](https://www.amazon.com/gp/product/B07QC6TTD8) * [Digital volt/current/power meter](https://www.amazon.com/gp/product/B013PKYILS) * Optional: [Different smaller meter that can measure lower voltages but has a lower current limit](https://www.amazon.com/McIgIcM-Digital-Voltmeter-Ammeter-10ADetector/dp/B06XR2XKNT) * Hookup wire. If you're going to be pumping out 10A, you probably want to use 18ga solid copper wire or 14ga stranded copper wire for the internal connections to be safe. If you're going higher than 10A, [this chart](https://www.engineeringtoolbox.com/wire-gauges-d_419.html) should give you and idea of what you should use to keep from burning your house down. * Optional but strongly recommended: [Fuse holder](https://www.amazon.com/SIM-NAT-Automotive-Standard-Replacement/dp/B07RY8Y2QV) * Optional: [5mm LED holders for 8mm holes](https://www.amazon.com/Copper-Display-Accessory-Light-emitting-Lighting/dp/B01M4RUY4M) * Optional: [5mm LEDs](https://www.amazon.com/dp/B07PG84V17) to indicate when a rail is powered on. * Optional: various resistors to keep the LEDs from dying spectacular deaths. Here is a [resistor calculator](https://ohmslawcalculator.com/led-resistor-calculator) so you can figure out what values you need based on which LEDs you use. This was designed in TinkerCAD. Here is the link if you want to play with it, fix all of my mistakes, adapt it for your own electronics, or whatever. https://www.tinkercad.com/things/4UFrefWXZW4 I'll post a wiring diagram when I get around to making one.