At 03:11 PM 10/6/2009, William \"Chops\" Westfield wrote: >The problem with most isolated DC-DC converters is that they end up >using some custom-made transformer designed for optimal efficiency in >exactly that circuit. Surely there has to be SOME standard low-cost >magnetic component suitable for <50mA worth of power isolation? >(thinking of: "Joule thief" bifilar ferrite bead, 600ohm telco >transformers, ethernet magnetics, DSL magnetics, etc...) Exactly. The version of this that I have built the most of (multi-hundreds) uses a small common-mode choke that I bought for perhaps US $0.20 each or so. Not exactly designed for the purpose but works well enough. There's a pretty good chance that it will work with Ethernet transformers (I haven't characterized one of those yet) and it for sure will work with cheapo audio transformers. I've run the converter as low as 10 KHz and as high as 500 KHz. I'm finally getting off my butt and have written Electronic Design about submitting it. I'm not sure what the rules are, but I'd think that I can post it after they have printed it. I also don't mind sharing it privately even before that. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist