This circuit uses an HA2400 consisting of 4 digitally controlled operational amplifiers. The circuit is from a Radio Electronics magazine from March 1980. The power supply must be symmetrical.
The circuit in the figure indicates when the input voltage exceeds a certain value adjusted by the...
We found this circuit in Radio Electronics magazine from May 1962. The circuit uses rectifier...
This circuit, from a 1974 publication, can be assembled with BC548 transistors. If powered with 6 or...