tedk@ihuxv.ATT.COM (Kekatos) (11/14/87)
In article <4948@sdcrdcf.UUCP> darrelj@sdcrdcf.UUCP (Darrel VanBuer) writes: >In article <3165@husc6.UUCP> lucius%tardis.harvard.edu@harvard.harvard.edu (Lucius Chiaraviglio) writes: >>In article <3226@aw.sei.cmu.edu> rsd@sei.cmu.edu (Richard S D'Ippolito) writes: >>>Thyristors are solid state switches used to control power, and are found in >> Yes, but how do they work? Are they sort of like giant transistors? >Yes, sort of, however unlike a transistor, once turned on, they stay on >until power is removed (usual method for AC current which goes to 0 120 >times a second), or a large enough inverse gate current is supplied to turn >it off again. Also, they are switch mode devices, only ON or OFF. Power >regulation is achieved by varying the on time duty cycle. >-- >Darrel J. Van Buer, PhD; unisys; 2525 Colorado Ave; Santa Monica, CA 90406 Thyristors act like two SCR's in one device. An SCR switches to full on when proper gate trigger (current) is applied. I can not be turned off unless the load circuit is current is removed (as stated above). If I'm not mistaken, A Thyristor could be subsututed by two SCRs. ______ _______ _____ _______ ------- Ted G. Kekatos / __ \ <__ __> / __ \ <__ __> -====------ ihnp4!ihuxv!tedk | (__) | | | \ \ \_\ | | -======------ | __ | | | / _) __ | | --====------- AT&T Bell Laboratories | | | | | | ( (__/ / | | ----------- Naperville, Il 60566 |_| |_| |_| \_____/ |_| -------
mc68020@gilsys.UUCP (Thomas J Keller) (11/16/87)
In article <2236@ihuxv.ATT.COM>, tedk@ihuxv.ATT.COM (Kekatos) writes: > In article <4948@sdcrdcf.UUCP> darrelj@sdcrdcf.UUCP (Darrel VanBuer) writes: > full on when proper gate trigger (current) is applied. I can not > be turned off unless the load circuit is current is removed (as stated > above). If I'm not mistaken, A Thyristor could be subsututed by > two SCRs. Ah, but you *ARE* mistaken! SCRs, GTO-SCRs and TRIACS (among others) are *ALL* thyristors. GTO-SCRs, by the by, *CAN* be turned off. SCR : Silicon Controlled Rectifier GTO-SCR: Gate-Turn-Off Silicon Controlled Rectifier A triac is essentially two SCRs back to back, with their gates connected together. -- Tom Keller VOICE : + 1 707 575 9493 UUCP : {ihnp4,ames,sun,amdahl,lll-crg,pyramid}!ptsfa!gilsys!mc68020
wolfgang@mgm.mit.edu (Wolfgang Rupprecht) (11/18/87)
In article <1152@gilsys.UUCP> mc68020@gilsys.UUCP (Thomas J Keller) writes: > A triac is essentially two SCRs back to back, with their gates connected >together. This is true in the same spirit as a transistor is just two diodes hooked back to back. An SCR is a 4-layer device (p-n-p-n) and a TRIAC is a 5-layer device (p-n-p-n-p). One can't fully describe a triacs 4-quandrant operation (gate vs. anode voltage polatity) by modeling it as 2 SCRS. That would only account for 2 quadrants of operation. Any basic electronics text can clear up these mysteries. Wolfgang Rupprecht UUCP: mit-eddie!mgm.mit.edu!wolfgang (or) mirror!mit-mgm!wolfgang ARPA: wolfgang@mgm.mit.edu (IP addr 18.82.0.114)
pavelz@tekigm2.UUCP (11/20/87)
SCR = Thyristor. Triac = Bilateral [Triode] Switch. To switch AC, you can use either: 1 SCR + 4 diods. 2 SCRs 1 Triac. There may be different names as well, but these are most popular in data books I look into. Pavel Zivny