Doulwel posted a topic in General DiscussionHas anyone had problems getting a solid state relay to work? After asking my friend, I have learned some lessons: don't accidentally take out current limiting resistor solid state relay rated for AC load will probably just turn on small DC load. It makes a LOT of sense that since there's an LED inside you need a resistor, that's a Basic concept. I'm using a SSR to control a AC load. To test it I'm using an LED load. The problem is, I can't get the relay to turn on. I'm using the S202S02 from Kynix. First a was using a uP (Atmel XMEGA128A1) but that wasn't working so I switched to just straight up using Vcc. (Note: I didn't bother with a transistor, just connected it right to uP) The SSR has 4 pins: the output pins (indicated by the AC tilde) and two input pins: + and -. The problem is that I apply vcc (3.3/5V) to plus, ground - and then connect one output pin to vcc and the other pin to an led which is connected to a resistor and then ground. I know the led works because if I connect vcc to it it turns on. What am I doing wrong? I'm pretty sure SSRs can switch DC loads. I've used two different relays in my circuit so I don't think I have a bum relay.