Wire an SSR to a DB25-1205 BOB 1

Wire an SSR to a DB25-1205 BOB


These instructions will show you how to wire an SSR (Solid State Relay) to a DB25-1205 breakout board. The DB25-1205 breakout board does not have any onboard relays, so you’ll need to add an external one to be able to control higher voltage devices such as:

  • A Router,
  • A Vacuum,
  • Water Pump, and
  • Other devices.

These instructions follow on from “Wire an AC Router to an SSR”, please read them as well.

Check that you can see the pronged plugs of the router and extension cord are not plugged in.
Best practice – hold the plugs in your hand and visually trace the cords back to the router and other end of the extension cord. This will confirm they are not plugged in.

Parts Required

1. Solid State Relay – SSR
An SSR is basically an electric switch.  It will allow you to use a DC circuit (your breakout board) to turn off/on an AC device (your router for example). SSRs are usually ladled with their amperage capacity and which type of current is used to trigger it and what type of current it can switch. Please make sure the SSR you order ends in DA. The “DA”, as the “D” is first it means the low voltage trigger current is DC, and the “A” being second means it can switch off and on an AC current.

2. Wire 1.5mm or 2.0mm
This will be used to wire the low voltage side of your SSR to your breakout board.

3. Fork Crimp Terminals
Fork Terminals are used connect wires to screw terminals and are a tidy way to terminate a wire. They are fairly cost effective and can be used by people who  don’t have access to soldering equipment. 

Tools Required

Wire cutter

Wire stripper

Small flathead screwdriver

Crimping Tool

Philips head screwdriver


Unplug Power Cords

Make sure both the extension cord you are going to use for your router and your CNC electronics are unplugged. Visually identify both the male plug ends of your cords and that they are not plugged in to wall sockets, place them on the bench beside you. If I sound like I’m repeating myself, well I am – its important!


Initial Setup of DC wires

You’ll need two lengths of 1.5mm – 2.0mm wire to connect the SSR to the DB25-1205. One will be used for DC5V+ and the other for DC5V-. Colour is not important but if you use red for “+” and black for “-“ it may assist you latter on when fault finding knowing you have used consistent wire colouring throughout your enclosure. The length needs to be enough to start at the SSR go all the way to the BOB.

Then strip back the individual wires around 4-6mm each. Give each wire a twist and make sure there are no loose strands sticking out.

This is optional but recommended. Place a fork terminal on one end of both wires and crimp the fork terminals with an appropriate tool. Test by giving both of them a tug to see if they come away, if a fork terminal does come away, dispose of it and start again.