Tv-B-Gone Hat

Step 3 Attach the Relay

If your relay did not come with a datasheet or any useful information you will probably have to figure out which pin is which on your own. To do this use a multimeter checking between all possible combinations of pins to find a pair which have a resistance of a couple K ohms. This is the coil. Connect the coil to a 5v supply and check for continuity on other pin combinations, when you find a combination that is continuous, remove power from the relay. If the two pins are still continuous keep looking (also try reversing the polarity of the 5v supply). If the connection breaks then these are the NO (Normally Open) pins, the pins we want.

Connect the output of the 555 to the + side of the coil and connect the coil gnd to pin 1 of the 555. Next add wires to the two pins you just itdentified as the NO contacts.