Dave Tweed wrote: > > Roman Black wrote: > > Hi, in messing around I came up with a *really simple* 2-tran boost > > circuit that gives 13.3v regulated output from a regulated 5v input. > Yes, please do. I'd like to see how it compares with one that I came up > with a few days ago. I need a regulator that can take a battery voltage of > 3-4 volts and provide 5V at up to 100 mA max with good efficiency. Hi Dave, i'll post my circuit here but it really is not very suitable for your PIC supply use? 470uH 1N4148 +5v ------*-----*---L---*---------*---->|----------*---*-- 13.3v (reg) | | | | | | 12mA in | | | | | | max. | R1 | | | | out | 10k | C | | | | *-----B NPN | 15k | | | | E BC337 R4 13v | | | | | | zener | | 22uF | | | | 400mW - | 4.7uF 16v C '-------|---------|----, ^ C 16v | | | | | | | | | C | | | *----R3---*--B NPN | | | | 1k | E BC337 | | | | | | | | | 6.8 R2 C | | | | ohm | | | | | | | 1nF | | | | | | | | | | Gnd ------*-------------*---------*----*-----------*---*-- Gnd My circuit is a *constant power* system that dumps a set amount of energy into the 13v zener. It's only good for tiny output current, but pretty much any output voltage by just changing the zener. It has two good features; R1 can be connected to a PIC pin, and turns the thing on/off when it is needed. Also oscillation (turn off) occurs when the coil current reaches a set level, giving very reliable operation and known max coil current, and hence input power. When running it always draws 5v @ 46mA, output is 13.3v up to 12mA. It doesn't start well on full load or with a large output cap. It DOES work perfectly for generating a 13v programming supply from a normal 5v source. :o) -Roman -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.