I'm having some admittedly embarrassing trouble with a SSR I'm using for a reflow oven with an ESP8266, MAX31856 I'm slapping together. No matter what I do, the SSR is not passing current
Here is a schematic of the SSR from BigClive:
The SSR is on the low side of the circuit: 120+ straight from the wall -> Resistive elements -> SSR terminal 1-> SSR terminal 2 -> 120V- straight back to the wall. I've verified that when I connect the wires connected to the two SSR terminals manually (and safety), power is passed through, the elements get hot, and everything is fine. So its just the SSR NOT triggering. I've tried 4 different SSRs albeit from the same AliExpress order. I've tried swapping the AC leads (not that it should matter), and I've tried putting the SSR on the high side (120+ -> SSR terminal 1-> SSR terminal 2 -> Resistive elements ->Ground.).
I'm using PWM from an ESP8266. Default setting from the Arduino toolchain is 10bit at 1Khz frequency. But I've also tried 10hz frequency. I've also of course just set the output on (PWM 100% duty cycle). I've verified the PWM is functioning with an oscope. The SSR also has an in-built LED that is dimming with response to my inputs, so I know its getting a signal. I haven't tried just giving it input side off the SSR like 10V or 24V from a bench power supply. But it shouldn't matter....?
All I can think right now is that I got a bad batch of SSRs from AliExpress. I mean...its not complicated, this should just work. What am I missing? Is there something I'm missing.