Using an operational amplifier, this circuit from a 90s Popular Electronics, is characterized by its high sensitivity. R5 can be added to control the gain.
We found this circuit in Radio Electronics magazine from May 1967. The circuit has the tuned...
This circuit is based on a regulator component that consists of a transistor and zener in the same...
This circuit, based on a 555, was found in a Popular Electronics from the 90s. The circuit has the...