This audio level indication system for microphones was found in Radio Electronics from the 90s. The components used are common today.
The coil and sockets of this circuit found in a QST depend on the frequency band that is intended...
Indicated for discriminators adjustment in FM and VHF receivers, this circuit was found in a 90s...
Mouser Electronics is making available the Texas Instruments DRV401 Q1 integrated circuit, a...