/Important note: There is a (fatal) error in the design! It doesn't work the way it's published here! Please stand by until I find the time to get it sorted out. Thanks NOTE: This is an untested prototype design. I currently have very limited time available and won't be able to make and test one myself in the next few weeks. However I wanted to get this out because I know some people have been waiting for it for a long time now. Disclaimer: UNTESTED DESIGN! Please try out responsibly and be prepared to face problems with this. I believe it will work fine. It's a simple design and I am confident that there are no errors. If you don't think you're the right person to test this out, then please wait for someone to confirm that it's working fine. Some important documentation is still missing, but you should be able to make and use this using the information from the old design. About the improvements: Version 3 uses an optocoupler to isolate the input from the output voltages. This makes it universally usable with any 3D printer electronics platform and enables you to use one power supply unit for everything, or separate units. Performance is identical to V2 - this thing shouldn't get warm during operation, at least not in "bang bang mode". PWM mode is not recommended for the heatbed. You could try, but keep track of the mosfet's temperature.