SSR help needed

Forum 2005-2010 (read only) Hardware Interfacing
1

I have a solid state relay (http://www.futurlec.com/Relays/SSR10A.shtml) that I would like to use to control a metal halide light for my fish tank. I have the circuit set up, and it is sort of working.

The output is on Arduino pin 13 which for now is just turning on and off every 10 seconds to test the relays. My problem is when the Arduino is commanding a low output, the test light (a 120v lamp) has a small flicker. When the output is high, the light is on.

I measured the voltage at the plug I am controlling, when the arduino out is high, 120v. When the arduino out is low, 120v...?

Circuit info - Sorry i don't have a drawing on my pc

pin 13 of the arduino is being pulled up with a 10k resistor and driving the + input of the SSR. The - of the SSR is going to ground. The output of the relay has 120v coming in on pin 1, and pin 2 going to the hot side of a wall plug. The wall plug has common on the other side and the ground wire where the ground goes.

Why do I see 120v across the load side of the relay when the adrino is commanding a low? This has to be the reason for the slight flicker in the lamp, right? And most important... How do I fix it??

Thank you for your time and help!

2

I just thought of some more notable information about the SSR.

When the SSR input is low, the resistance across load is 17m ohms. it is the same when the SSR doesn't have anything hooked up to it. When the SSR input is high the resistance across load is about 7k ohms.

Thanks!

3

Take out your pullup resistor.

That's only needed when the pin is an input, not an output.

Basically by having it in the circuit, you are turning the SSR on ever so slightly.

4

Thanks for the help. I took out the resistor and it works great!

I knew it was going to be something like that. I was over thinking the problem.

Thanks!

5

:sunglasses: