Re: Diodes and SCR's

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ben McMillen by way of Terry Fritz <twftesla-at-qwest-dot-net>" <spoonman534-at-yahoo-dot-com>

Hi Scott,
  As far as I know, Thyristors (SCR's) can't be used as
diodes.. at least not in the full wave bridge sense the way
regular diodes are used.... They're like one shot
switches.. well, as the name puts it, "Silicon Controlled
Rectifers".. They're like a diode with a gate.. once the
current starts flowing (initated by a pulse at the gate),
it doesen't stop until it's interrupted.. But you probably
already know that.. ;)

  They CAN be used in a rectifier setup, but you need
firing circuitry to control when they turn on in the AC
waveform (called firing angle).. So I guess the answer is
yes, they can be used as rectifiers, but not in the more
commonly known sense.. How to do that is a question better
answered by someone else.. 

I understand how they work, but I'm not so sure I can
explain it properly.. ;)

Coiling In Pittsburgh
Ben McMillen

--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "BunnyKiller by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <bigfoo39-at-telocity-dot-com>
> 
> Hi All...
> 
> got a question about diodes and scr's
> 
> 
> can a scr be used as a diode?   well....  can 4 scrs be
> used as a full 
> wave bridge rectifier???  and if they can be used as a
> FWBR  how does 
> one wire up the gates to do so??    
> 
> I just found out that the diodes I have been using in my
> power supply 
> are rated for 100 V 70 A ( set up as a full wave BR) and
> Ive been 
> pumping 300VAC into them at 60A ....  either I blew up
> something and 
> didnt see it go  OR...  these diodes are EXTREMELY
> underrated and are 
> handling the abuse. Ive loaded the "DC" side and checked
> for ac ripple 
> and there wasnt any of appreciable amount ( 300VAC in  
> 390DC out...   
> when under load, 310VDC -at-30A  with 8 vac ripple.)
> 
> also ...  are any of you interested in selling some old
> stocked diodes 
> or FWBR' s that are sitting in the dust pile ( preferably
>  600+V at 
> 100A+ ) I'd be really interested in them.
> 
> Scot D
>