This circuit was obtained in an Electronics Now from the 90s. The circuit uses operational amplifiers from the time and the indicator is of the Sonalert type with internal oscillator.
This circuit provides an output voltage approximately 2 times that of the input voltage. The...
The operational amplifiers of this circuit can be replaced with more modern equivalents. The power...
We found this circuit in a 1964 publication. The circuit is both an amplifier and an oscillator for the...