Thanks, I came too late into this discussion, yes the preferred voltage is 3.3 V, but if decoupled by a emitter follower , maybe 4 V is a good choice. Can you please copy /past me the info? Thanks Ulrich In a message dated 12/4/2016 3:12:18 P.M. Eastern Standard Time, jimlux@earthlink.net writes: On 12/4/16 11:46 AM, KA2WEU--- via time-nuts wrote: > Who has a good recommendation for a switching power supply circuit, 12V DC > in, 4 V/ 500mA out , Exactly 3.3 for IC voltage. > do you need 4V or 3.3V? I'd start with one of the modular parts we've been discussing. They typically have 9-18V input range and whatever you want out. Since I have the Mouser search page up, P78A03-0500 is $3.71 in qty 1, 3.3V out @ 0.5A, 6-28V in. ABout 85% efficient _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.