This circuit was found in the June 1995 Electroics Now magazine. The relay should be a sensitive type with up to 100 mA trigger current.
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...