4pcs DC 12V Relay Module 2 Channel Relay Board with Optocoupler Support High or Low Level Trigger

These are fast to install, work perfectly on all my product rebuilds where I need a fast solution, and work in any product needing what these are. The price is unbeatable, the quality appears to be strong, and they are small enough to fit nearly everything. I expect to be using these consistently for many years!

Nice form 5 function relays which basically switch between one load or another. In this case a vehicles standard fuel pump is "dropped" and a second fuel pump in a smaller tank of race gas is activated along with increased boost via boost controller when the "race" toggle is thrown. The black plastic 2-pin jumper can be swapped over to the other 2 of 3 pins for - 12V trigger. All mine came set for +12v trigger, and I preferred having everything work through switching grounds. If these don't work you likely have a negative trigger and need to move the jumper block over.

Nicely constructed and easy to interface with. Hard to beat the price.

At first I thought I got lemons because they would not click at if applying 5V DC on low power side according to description. Then I applied 12V DC and they clicked, then I forgot to share the ground when using an ESP32 5V DC sending a 3.2V signal that would trigger both relays at the same time instead of separately, once grounds shared, they worked properly.

I just needed to activate with a 12 volt DC source and keep blowing these up. I do not understand the Hi - Lo part. I watched a video and use my 12 volt source on " hi " setting to activate. They still light up will not close the relay when I apply the 12 volts. I have use ones that look so much like these but not the Optocoupler Hi Lo so, please if someone can tell me how these are to be used please do. I could only find that one video where I could se he was doing the same, 12 volts to the "hi" setting to activate. Other wise seems like a great item.

After reading the reviews, I tested these on the bench before installing any. 2 of the 4 boards work properly. 1 of the 4 has a dead relay. The last has a non-functioning power light. The good ones seem to work fine but you have to wonder what's going on with the total absence of QC checks before shipping these out the door.

Works like described Good!

Just bought these for a small model train project. I’m now having to return them because neither of the two relays on any of the 4 modules work…. Cheap garbage