2pcs DC 12V Relay Module 4 Channel Relay Board Shield with Optocoupler Isolation Suport High/Low Level Trigger

An excellent product, never had any problems. However, this has a than 5 volt trigger, and for automobile use one would have to use a resistor inline with the control voltage for the longevity of the optoisolator. I used a 1.2k resistor, in series with my control line. I have some other mods, cut come traces on the top and bottom so I have one source of switched voltage and not multiple lines in on each relay. I use this to switch on and off some Raspberry Pi's in the truck for power up, or reboot when needed.

Works exactly for what I need it for and I have a spare since I got a 2 pack

Been working flawlessly for several months as part of a power sequencer I made.

Makes using relays super easy with a configurable shorting jumper to select either positive or negative input signal. Has power on and relay activated LED for easy troubleshooting and signal conformation.

I use these relays circuit ti control air suspension solenoids on a motorcycle.... They handle pretty good and did not see any fail. I used these circuit to keep everything tightter and compact as possible

Always handy to have on hand.

These work great for opening and closing garage doors remotely. Anything that uses a push button momentary switch. Paired with a Raspberry or Arduino and some python code and you are in business.

Did a check on the relay and all 4 relays appeared to function using high or low signal trigger (audible and LED check only, no continuity test). Both boards were fine. Relays were not the ones shown in the listing but are the same I've received on other similar boards [ Songle ].