----- Original Message ----- From: "Tim ODriscoll" To: Sent: Friday, August 15, 2003 2:37 PM Subject: Re: [EE:] 24vdc from a 15vdc psu > On Sat, 16 Aug 2003, Jinx wrote: > > You could use a 7824 or jack up the reference pin (or "ground" > > as it's commonly used) of a 7812 with a 12V zener. Or a 7815 > > and a 9V1 zener. The anode of the zd goes to circuit 0V and the > > cathode (band) to the reference pin of the reg. Take a few mA > > from the 781x output back to the zener cathode to keep it steady > > > First off, Thanks for all the replies. > > This is the idea I was thinking of. The only similar example I can find is > this: http://www.mitedu.freeserve.co.uk/Circuits/Power/alarm_psu.htm > > It's just like you say Jinx, but with a 7805. > > And best of all, I've already got the parts for it in my junk drawer :) > > Cheers, > > Tim If you can tolerate a novice question, I'll appreciate an explanation of how the output of the 7805 circuit in the http://www.mitedu.freeserve.co.uk/Circuits/Power/alarm_psu.htm diagram is 14v1. Thanks in advance if you will. If not, I understand. Chuck H. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.