2 of 2 people found the following review helpful
Not A Toy, But Really Fun To Play With!,
= Durability: = Fun: = Educational:
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This review is from: SainSmart 8-Channel Relay Module (Electronics)
This is a great board at a really good price. The only con is that the relays are triggered with ground/low instead of 5v/high which was problematic for me if I need to restart the board as I am controlling a vending machine and the Arduino/Firmata initialization causes the pins to be low and disconnected several times. I solved this by lifting the ground with a transistor on a digital output and setting that high after the init is complete. This way the relays don't trigger, although the LEDs still light up.