Looking for practical Arduino projects? This guide shows how to control a relay from your smartphone using an Arduino Uno — ...

One advantage of solid-state relay (SSR) over conventional electro-magnetic relay (EMR) is its tear and wear free operation. S201S01 from Sharp is a good example. Here is the circuit diagram of a DIY ...

The diagrams and photos show how to wire up the fuel pump and oil-pressure switch to a commonly available, industry standard, ISO-type "1 Form C single pole/double throw" (SPDT) relay.

Another circuit requires two control lines to set and reset the relay (c). Two other circuits have a supply-voltage range of 2.7 to 5.5V and a maximum quiescent current of only 50 nA (d and e). The ...