On Thursday 30 August 2012 17:54:32 Kent A. Reed did opine: > On 8/30/2012 11:22 AM, Gene Heskett wrote: > > I need a better power > > transformer for that setup anyway, preferably a toroid that can supply > > 500 watts into a FW bridge at 45 volts. They seem to be made out of > > unobtainium though... > > I can scarcely believe you haven't already rolled your own ;-) > Believe it or not Kent, I have. Switchmode to boot. Circa early 1982. I needed a psu for an automatic transmitter controller I had built the 2 years I was Chiefing at KSUE-AM-FM, that would survive the about 30 seconds between a power failure and the standby generator becoming available. The board didn't need a huge amount of power, so I cabbaged a 75 volt, 85k uf electrolytic cap, and designed and built a switchmode buck regulator from that fully charged capacitor to about 7 volts to feed the boards 7805. It would hold up nearly 1:30. I wound the transformer myself. In retrospect, I had room for the next heavier gage of wire because it ran moderately warm. Hexfets were only on the distant horizon then, so the bipolar bug also contributed its share of heat, switching way too slow.
> Kidding aside, there are times I wish I could lay my hands on some scrap > toroidal power transformers suitable for rewinding to my requirements. > About all I can find close at hand are old kitchen microwaves all of > which I've seen come with classic E-I type transformers. And nowhere near rated for CCS duty without active cooling. So do I, if you should stumble over a suitable surplus piece they have 50 of, I'll take 2 right up front in a heartbeat. > Regards, > Kent > > > ------------------------------------------------------------------------ > ------ Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. > Discussions will include endpoint security, mobile security and the > latest in malware threats. > http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! Gary Hart: living proof that you *can* screw your brains out. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
