Funny this suggestion should come up at just this time. See EDN, February 6, 2003, Page 86, "design ideas, Polarity protector outperforms Schottky diodes".
or http://www.edn.com The circuit seems to have been designed to address your requirements. So far as understanding Triacs is concerned, I find that (like learning the theory of almost any device) the manufacturers data books and application notes are usually the most useful sources. For this case check out http://www.onsemi.com/pub/Collateral/DL137-D.PDF, "Thyristor Device Data", Chapter 1, Section 2 addresses theory of operation. Bob Smith --- Avoid computer viruses, Practice safe hex --- -- Specializing in small, cost effective embedded control systems -- Robert L. (Bob) Smith Smith Machine Works, Inc. 9900 Lumlay Road Richmond, VA 23236 804/745-1065 [EMAIL PROTECTED] ----- Original Message ----- To: "Multiple recipients of list CHIPDIR-L" <[EMAIL PROTECTED]> Sent: Thursday, February 13, 2003 5:29 PM > The circuit should draw about 1.0A-1.25A. Sounds like a good > idea if I can determine a good, cheap trigger circuit. > Thanks, > > At 01:30 PM 2/13/03 -0800, Peter Vogel wrote: > >Here's one I use that I don't think has been suggested. > > > >I use a MOSFET in series at the input, arranged to switch off on > >over-voltage. I didn't notice what current your circuit draws, but if > >you use a T0220 with a few milliohms resistance you get only a few > >millivolts drop when on. Because you switch it off on over volts, no > >power is dissipated. Use something like 100V device and it's > >bulletproof. > > > >To protect against reverse voltage you have little choice other than a > >reverse diode across the input. > > > > > >BTW What is the total current drain of your circuit? > > -Bob > -------------------------------------------------------------------- > Robert Ritchey > Quest Engineering & Development > 1328 East Cottonwood Lane > Phoenix, AZ 85048-4765 > Tel: (480) 460-2652 > FAX: (480) 460-2653 > E-Mail: [EMAIL PROTECTED] > E-Mail: [EMAIL PROTECTED] > E-Mail: [EMAIL PROTECTED] > E-Mail: [EMAIL PROTECTED] > WWW: www.QuestEngDev.com/ > WWW: www.Smart-Fly.com/ > -------------------------------------------------------------------- > > -- > Author: Robert Ritchey > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB CHIPDIR-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). > > -- Author: Robert Smith INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
