Relay connections to Arduino Uno

Hi all,
I am putting together an oven reflow project in conjunction with the Arduino Uno.
I'm feeling my way with this project and the only thing I am not comfortable with is connecting the relay to the Arduino, which is not clear from the on-line pic (see below);

I've trawled the net for an answer but can't find anything clear enough to help me. It appears that the relay in the pic ( I'm using the same one) connects the +ve rail from the relay to pins 12 or 13 & the -ve rail to the GND pin, but I'm not sure.

Could you help by clarifiying these connections?

Thank you for your help.

The link to the toaster oven page gives you this:

The solid-state relay has four connections. Two go in series with the mains live wire. The other two turn the mains current on and off.
The neatest thing to do with the solid-state relay is to mount it inside a mains plug patress box. You will then have a general-purpose device that will allow you to control any mains load (up to 5A) with the Arduino. Run the control wires out of the side of the box and connect them to the Arduino: + goes to the Arduino LED (D13 on an Arduino Diecimila), the other control connection goes to the Arduino ground.
Note that there is no electrical connection inside the solid-state relay between the control circuit and the mains circuit. The device is optically coupled, so there is no danger that you will get mains flowing through your Arduino (as long as you wire things up right...).

It appears that the relay in the pic ( I'm using the same one) connects the +ve rail from the relay to pins 12 or 13 & the -ve rail to the GND pin, but I'm not sure.

You need to connect the - pin on the input side of the relay to ground and the + pin of the relay input to the Arduino pin you want to use to trigger the relay. The "business" end (output) handles the mains (pay attention to that part so you don't die).

Doing it like the pic with the relay attached inside a junction box is good. I can't tell what the black part in the lid of the box is but one could make it a standard wall outlet that one sticks a plug into.

I gotta get me one of those Crydom relays. They look really good but I haven't pulled the trigger yet becasue the cheapest I've found them is still like US$15 or $20.

But what pin triggers the relay (pins 12/13?).
I can't seem to find any information that tells me what each of the 13 pins do, or indeed, what that bank of pins is called! Which is the LED pin on the Arduino Uno? Is it the same as D13 on an Arduino Diecimila?
Thanks again.

From my limited ipad screen it appears they are using pin 13 connected to + and the GND pin next to pin 13 going to -
But you could use pin 12, just write your code accordingly.

I agree with LarryD. You can use any pin you want- all you are going to do is write a pin HIGH to switch the relay.

Hi, what level of experience have you had with arduino, electronics and construction.

Can you post a copy of your sketch and we will be able to tell you more about the pin allocations.

You can regard the SSR as a switch that has no electrical connection between the input connections and the output.

The input is connected to an opto coupler inside the SSR, when current flows through the coupler it turns on OPTICALLY a TRIAC, which is an AC solid state switch.

Tom..... :slight_smile: