AC Relay Module

Introduction: AC Relay Module

I was sorting through all my salvaged electronics deciding what to keep and what to throw away. I had saved this IR controlled AC switch that was missing its remote control with hopes to build an IR remote to control it. I had decided it wouldn't be worth my time and started to open the case up to salvage the parts when I decided why not just connect straight to the relay. So that's what I did, now I can switch the outlet on and off using 12 volts.

Step 1: Tools and Supplies

For this project I used a Hakko FX-888D soldering iron I bought on, helping hands and clamp on vise from harbor freight. I also used a pair of needle nose pliers and snips. The small wires I used came from an old Ethernet cable that I cut open. I used some silver solder that I got from Radioshack and some lead free tip tinner from Amazon.

Step 2: Open the Case

Take the screws out of the back the case and carefully pull the circuit board out.

Step 3: Find Relay Coil Wires

Look for the relay, then look on the opposite side of the board and look for the two small contacts that are directly opposite the relay. When those two wires have 12 volts connected to them the relay closes and connects the AC wire.

Normally when 12v isn't connected to the relay coil the 110v hot wire is disconnected. I used a 9v battery and two alligator clips and tried touching them to the pins that I thought were the relay coil. You will know when you touch them because you will hear the relay click.

The two pins that make the relay click are the ones that we will be soldering wires to in the next step.

Step 4: Solder Wires to Contacts

Solder the two small wires to the relay coil pins you found earlier. I used a bench vise to hold the circuit board in place and helping hands to hold the wires. Don't forget to tin the tip of the soldering iron between solder joints.

Also be cautious and don't remove to much insulation from your wire. You want as little exposed wire as possible so when you fold it over and put it in the case it doesn't short out to any other contacts on the board (especially the 110v contacts). You could also use hot glue to cover the contact and the wire so that it doesn't bump any of the other contacts.

Step 5: Secure Wire

Drill a small hole in the side of the case that you can put the two wires through. Then put the pcb back in the bottom half of the case. Then take a zip tie and attach it to the wires so that they don't pull loose from the board and come through the hole. Then put the wires through the hole you drilled. Then snap the case back together and reinsert the screws.

Step 6: Done

Now you have a complete 12v controlled switch for a lamp or some other device. Remember to check the manufactures specs and don't go over their recomendation for wattage on connected devices.

Also remember, no two circuits are the same so use caution when building this. I am not responsible for any accidents or losses that occur.

Step 7: Optional

Depending on the circuit you might be able to find a 12v on the board, if you do, you could use a transistor to connect it to the relay that way you could control the 12v relay with 3-5v from an Arduino or Raspberry Pi. Be careful though, I gave up because I could only find low voltage on the board except for 110v. I accidentally shorted the board out and had to replace the fuse that had exploded on me.

Step 8: Vote

I have entered this instructable in a couple of contest so if you liked this instructable please vote for it.

Thanks for reading :)

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    Danang JKT
    Danang JKT

    6 years ago

    Nice trick. I wanna make converter from 220AC to 18V DC. Can you help me how to make it? Diagram pictures will be helpful, thanks.


    Reply 6 years ago