Impulse relay turns on with an electrical impulse at the control input and turns off again with another impulse.

If you are designing your own intelligent “Graden Computer” with an optional digital plant moisture sensor/water pump controller that lights an LED to alert the user when it is time to water a potted ...

Basic circuit diagram of one of its channels is shown ... Also note at this point that, if you want perfect galvanic-isolation, do not link Arduino’s ground rail (Gnd) to the relay module’s ground pin ...

[Jason] really wanted to build an RFID controlled garage door opener and decided to turn to Arduino to get the ... the user to select how long the relay circuit should remain open.