Review on SainSmart 101 70 100 2 Channel Relay Module by Philip Lindsey

As other reviewers have said, this is not a toy. I use together with Arduino in a door alarm. Again, as another reviewer mentioned, the relay contacts must be pulled LOW to turn them on and pulled HIGH to turn them off. This differs from traditional relays. An example sketch that keeps turning them on and off: void setup() { // initialize the digital pin as an output. // pin 10 has relay 1, pin 11 has relay 2: pinMode(10, OUTPUT); pinMode(11, OUTPUT); } void loop() { DigitalWrite(10, LOW); //set relay 1 to delay(1000); // wait for a second DigitalWrite(10, HIGH); // disable relay 1 delay(2000); // wait 2 seconds digitalWrite(11, LOW); // activate relay 2 delay(1000); // wait for the second DigitalWrite(11, HIGH); // disable relay 2 delay(2000); // wait 2 seconds }