Based on the LF256 operational amplifier, this circuit was found in the September 1989 issue of Radio Electronics magazine. The indicator is analog, and the power supply must be symmetrical.
This circuit was obtained in a 1989 English magazine. Despite using a fixed 5 V regulator, it can...
With the feedback of the output circuit, the monostable acts as a frequency divider, that is, it...
In this circuit of an old American documentation, the input impedance is the same as the output...