[2-Pack] DC 12V Relay Module 2-Channel Relay Switch with Optocoupler Isolation High/Low Level Trigger

These work great for use with the arduino since you can grab the 5V on board the unit to power it up. Using the 3.3V for power will not pick these relays so you have to use the 5V but other then that they are great relays and can run up to 10 amps which is great for certain projects.

It works really well to trigger a high current device using a low level signal

Works with Pi just fine. No problems or additional parts needed.

The photo shows the new style of this great relay but what I received was the old style. You can tell them apart by the color of the jumpers. The new style has black jumpers while the old had yellow jumpers. The old style is a bit larger in size. The important difference for me is the old style triggers around 3 volts when the jumper is set for low trigger. The new style triggers around 2 volts. For some reason the 12 volt new style seems to be unavailable on Amazon at the moment so I’m getting them from China.

In general, I like these modular circuits as they save time and in the end money. However, on this purchase I had no such luck. One of the boards has a defective circuit that prevents the second relay from turning on even though it receives a trigger, and the LED indicates it is on. This unexpected failure probably due to less than stellar quality control caused me untold grief and extensive time tracking down and replacing the module I installed in my equipment. Thankfully I ordered the 2 pack and had a replacement on hand. The bad thing is I cannot return the order to Amazon as I used one of them.