fast shorting relay

[tuned99]

I am currently generating an AC sinusoidal signal for approximatley 60ms across two electrodes. However, after I shut off the function generator signal, there appears to be some post electrical ringing and reflection that I would like to eliminate. I would like to short the two electrodes together immediately after I finish generating the signal within several tens to hundreds of nanoseconds. In theory, I think I can accomplish this with a symmetric MOSFET but I am having difficulty finding one. All of the MOSFETs I can find are design for DC drain to source applications and all of the photovoltaic power FETs switch in the orders of milliseconds. Any recommendations would be appreciated.

 

[Skogsgurra]

What about a triac? Or two thyristors? Triacs are the simplest to use - only one gate - but limited power and voltage. I think that you can get 800 V (or 1000 V) at some 30 - 40 A RMS. This is continous rating and for your "crow bar" application it should be possible to go outside that range quite a lot - especially currentwise.

If you need higher currents and voltages, you have to use thyristors. You should be able to find units with hundreds - even thousands of amperes and at least a couple of kilovolts.

Triacs are not very fast. I guess that you have to do with microsecond delays. Nanoseconds will probably be difficult.

 

[nbucska]

What is the frequency amplitude ? Is the input terminated?
(50 Ohm ?)

How much attenuation do you need?







<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032