This circuit was found in a 1967 US publication. In it we have the implementation of a ring counter using only relays. Relay free contacts can trigger indicator lamps or LEDs.
In the figure we have a circuit suggested by National Semiconductor, using an operational...
Tone controls for audio applications can also be considered filters that must attenuate certain...
This circuit was found in an Argentine publication from 1973. It uses a common AM coil (50 + 50...