Simple 0.5 Hz 50% duty cycle pulse generator using only a SPDT relay, 2 resistors, a transistor and a cap. LED and 330 resistor are just for display. The frequency and duty cycle can be changed by manipulating the values of the 2 resistors and the cap. This can not be used for high frequency as you are limited by the mechanics of the relay but it is a cheap and simple way to get high power low frequency pulse outputs.
