Post by thread:[EE]: thyristors

Peter L. Peres wrote: > > > how do you switch that SCR off? Turns out, you switch > > a capacitor across the device which diverts the current > > around it for just a few micro(?)seconds and that's > > enough to turn it off. Pretty impressive, I thought. > > Barry, the two-thyristor scheme was used extensively for horizontal > deflection and HV circuits before HV transistors were available. Try to > get hold of a Grundig color TV set schematic from about 10-15 years ago. > Maybe Roman has one. It's a neat scheme. Of course the theory is discussed > in contemporary application notes (from ITT and others). We didn't get many German sets here, but I have seen that system. Some even used the deliberate ringing of the driven transformer to turn off the SCR. I do know I have a heap of those old Thyristors lying around, high voltage medium current TO-3 etc. Good paperweights. :o) -Roman -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

> > > how do you switch that SCR off? Turns out, you switch > > > a capacitor across the device which diverts the current > > > around it for just a few micro(?)seconds and that's > > > enough to turn it off. Pretty impressive, I thought. > > > > Barry, the two-thyristor scheme was used extensively for horizontal > > deflection and HV circuits before HV transistors were available. Try to > > get hold of a Grundig color TV set schematic from about 10-15 years ago. > > Maybe Roman has one. It's a neat scheme. Of course the theory is discussed > > in contemporary application notes (from ITT and others). Why not use igbt or powerfet? Cheep, have a ttl comp driver chip, you can turn off anytime you want, etc. udv Csaba -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body

Csaba, > Why not use igbt or powerfet? Cheep, have a ttl comp driver chip, you > can turn off anytime you want, etc. AFAIK, Triacs are a lot more cheaper than IGBTs or Power Mosfets. Atleast that is the case in India. And since they still are in production, its ample proof that a lot of people still use em. Don't take me for a Thyristor loyalist. But Triacs and SCRs can be very useful at times. Jeethu Rao -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

Jeethu Rao wrote: > > Csaba, > > > Why not use igbt or powerfet? Cheep, have a ttl comp driver chip, you > > can turn off anytime you want, etc. > > AFAIK, Triacs are a lot more cheaper than IGBTs or Power Mosfets. > Atleast that is the case in India. Some low quantity price in Hungary: thyristor 81RIA120 1200V 80A cc 22$ thyristor bt151 650V 12A cc .5$ IGBT BUP314D 1200V 42A cc 8.4$ IGBT IRG4PC 50F 600V 70A cc 7.4$ IGBT BUP200 1200V 3.5A cc 1$ PowerFet buk 444 500V 1.9A 1.25$ PowerFet buk 455 600V 4A 1$ IR2151 driver for igbt cc 1$ U 208B Thyr. driver cc 1$ > And since they still are in production, its ample proof that > a lot of people still use em. > > Don't take me for a Thyristor loyalist. > > But Triacs and SCRs can be very useful at times. Yes, but they have their own limits. udv Csaba -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads