[Amps] Solid state relay question

[Vic Rosenthal]

Ron wrote:
> 
> I use thes types of relays for many things.
> If you have the ones that actuate from 3 to 32 volts , it would be easy to get some
> interferenc from RF dropping the actuating voltage below 3 volts if you are running
> it at 5 volts.  The input circuit is opto -isolated so you are running an LED to
> fire a triac.

This one is rated 3-8v, although it said in the All Electronics catalog that it
'works on 12 volts'.  However, I felt that it would be best to stay within the
rating.

> Some of these devices wait for a zero crossing of the line to switch.
> If you get interference at a zero crossing spot , the triac would wait for the next
> crossing and you would miss a half cycle......this might be enough to surge the
> relay on the next half cycle.
> 
> I would suggest raising the actuating voltage so that you have a larger noise
> margin  or place a reasonably large cap across the input to let it run the diode
> for a few cycles should interference drop the actuating signal below 3 volts.

I certainly can put a capacitor across the input.  However, the input is quite
well-filtered for RF, having a pi-section filter at the relay.  Interestingly,
the filter did not seem to have any effect.  What did help was bypassing the ac
line.  I'm not sure I understand why this is so.

Vic K2VCO