Found in a 1967 General Electric documentation, this meter uses Nixie tubes, popular at a time when LED and liquid crystal displays did not yet exist.
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...