Solid State Relays

Hello Community,

I need some help in understanding Solid State Relays, and mainly the differences between non-cross and random cross SSR's.

I am attempting to rebuild my Christmas light controller, and after doing some research, I came across a YouTube video of a gentleman utilizing SSR's to create dimming via PWM. The question here is he specifically mentions that he had to replace the SSR's he received with Random Cross SSR's...

What's the difference?

Thanks, M|O

Random means "non-zero-crossing" SSR, which respond instantly and can follow the PWM waveform. Zero-crossing SSR's only switch at mains zero-crossings to reduce switching transients and EMI.

Excellent. Thank you for your explanation, @MarkT.

MonorailOrange: I am attempting to rebuild my Christmas light controller,... a gentleman utilizing SSR's to create dimming via PWM.

Albeit, I know nothing about your "light controller", but if you (singular or plural) imply stock "Arduino PWM" then forget it. It's necessary to monitor the line for zero-crossing to coordinate the conduction/delay angles or you'll end up generating hash.

Fun with AC & holiday lights

@Runaway Pancake, I had thought about that over the past few hours. I had read that an H11AA1 DIP could be used to feed the zero-cross data into the arduino to avoid that. Would something like that work?

Yes, as in the link previous, an H11AA1 can be and indeed is used to catch the zero-cross.
Still, the conduction angle (“firing”) is a matter of pulsing; nothing like an “analogWrite”, if that’s what’s contemplated.