Review on SainSmart 101 70 100 2 Channel Relay Module by Terry Keown

Unfortunately, both of the devices I bought don't work very well. The relay required at least 5.8V to operate, which was unfortunate as I intended to power it from the RPi's 5V rail. . Adding a secondary voltage regulator just to drive the relay was annoying. Relay #2 on both units also fails, even with an input voltage of 5.8V. The input side of the board works great and has never given me any problems. The status lights for 1 and 2 are reliably turned on and off via the RPi's GPIO. Just a moment. I know other people have mentioned this, but the fact that these relays don't have a working normally open connection (they close on failure) makes them sketchy for use in my home automation project. an unsafe way to control garage door openers or alarm sirens.