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How to hook up 12V 8 relay modules without a micro controller. (VUPN688)

Written by Christopher on Wednesday, February 20, 2019.

This may seem simple enough to some. But its always nice to have some help when facing a new project!


This tutorial will allow you to make use of our 12V VUPN688 8 channel relay module without the use of a microcontroller.


These relay modules are optoisolated, so you can protect your switching circuit from the circuit being switched by the relays. There are some important notes at the bottom of this post that you may want to read. It could solve your problem quckly.


Heres what you need to do this project:

-1 VUPN688 12V 8 channel relay module.

-1 12V power supply

and some wire or dupont style jumper cables.


Step 1: Grab your relay module



Step 2: Connect your power supplies Positive Power to the VCC pin on the relay module



Step 3: Connect the power supplies negative wire to the GND pin on the relay module


Step 4: Power on your 12V power supply (or set your bench top supply to 12VDC)


Step 5: Branch off of the negative lead from your power supply (the one that you alredy have connected to GND on the relay board) and then connect to any one of the IN1 or IN2, etc and that will power the optoisolator which will switch the relay.


Once you do that, you will see the red LED on the relay board for the applicable relay.


Just repeat this process for each additional relay you want to run. Run one extra ground to each input, per relay you want to activate.


Some notes:

The down side of this relay module is that Ground is not common. In this circumstance Positive is the common. Which means that each relay needs a separate, individual ground connection to activate. As opposed to what people would normally assume where each INput would be a positive contact. It makes this very difficult to use with a microcontroller or in a situation where you want or need to controll something with positive voltage. Since microcontrollers usually use 3.3v or 5v logic, this relay module also could NOT be controlled buy such devices without extra transistors or more circuits that one might want to assemble.


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