This circuit was found in the November 1966 issue of Electronics Now magazine. It uses an LDR as a sensor and has a Bargraph scale with the well-known LM3914.
This automatic control for recording signal level was found in a Radio Electronics from September...
This switched-mode circuit was found in the April 1976 issue of Radio Electronics magazine. The...
This circuit, from a 303 Circuits from the 90s, uses a telephone pickup coil as a sensor to...