This circuit turns off a relay after a time determined by C1. The circuit was found in the December 1974 Radio Electronics magazine. The relay is rated according to the supply voltage.
This circuit uses two Raytheon RC4558 operational amplifiers that are similar to the 741. The...
This small stereo amplifier for headphones was found in a documentation on integrated circuits from...
This is a MOSFET version of a grid dip meter for frequencies between 1.8 MHz and 150 MHz,...