Solid State Relays and EMI

"David Harper" ...

Yes. The basic idea is to minimize the RF voltage occurring across the isolation barrier by shorting it with the cap. Input GND to output GND is best, to other points it might cause other EMC problems.

It _may_ help to also put a ceramic 1nF cap across the output. This lowers the RF voltage across the FETs, half of which would be present at the output side of the isolation barrier. But it will decrease the output impedance, so it's a second choice solution only.

Regards, Arie de Muynck

Which brings up the age-old question: Just how {anal-retentive, deliberately wrong} can one be on Usenet before crossing the line into "troll"?

Mercury-wetted?

It's OT gents.

RL

I think he meant to the common terminal (pin5), from various places in the circuit, including possibly an input drive rail.

RL

Tubes move electrons to function, semiconductors move holes to function :-).

Tim.