Superhack power supply
(click to enlarge) I'm not going to count this in the April Maker challenge. I don't know why. I hacked together a really hokey power supply for my tabletop foam cutter and as-yet-unbuilt acrylic bender (although strictly speaking, the portion of the foam cutter heating element that runs underneath the acrylic "table" has done a nice job of melting it). JTBarclay is using it for driving a 24V nigh-5W fan under a stir-plate, and Pat is building one for HIS foam cutter. It does a fairly good job, although it has no check on the amount of current it draws from the unregulated DC supply, which is a MAJOR short coming. The IC is an 8-pin PIC that I've programmed with a PWM controller that reads a pot to determine the duty cycle (at least, in this configuration it does). Because of the way the design works, you can put a limit on the duty cycle by inserting a resistor between the potentiometer and the ground rail. Using a smaller potentiometer is wise if you were ...