Dimming and non-Dimming relays

[spike]

I know there is a difference between dimming and non-dimming relays, but I cannot remember what it is.

I would like to order some dimming ones, but I know there's something special about them, and I can't remember what it is.

Is it the zero-cross function that you DO NOT want for dimming?

[ErnieHorning]

Non-dimming SSR’s have a zero cross detection circuit. When you turn them on, they will wait until the voltage drops to zero before actually turning on. This has the advantage that since the voltage is low at the time, they will produce very little RF noise.

The SSR’s that are meant for dimming don’t wait, they turn on immediately. Controllers will repeatedly turn the SSR on at the same point in each half of the AC waveform. They will produce more RF noise and could interfere with near by RF reception.

Edit:

You can use a dimming SSR for just on/off applications but not the other way around.

[Macrosill]

I know there is a difference between dimming and non-dimming relays, but I cannot remember what it is.

I would like to order some dimming ones, but I know there's something special about them, and I can't remember what it is.

Is it the zero-cross function that you DO NOT want for dimming?

Correct. You want non-zero crossing relays.

Zero cross relays do not dim.

[spike]

thanks guys
just making sure before I spend a lot of dough