The cut-off frequency of the circuit shown in the figure is 750 Hz, with the components used. The circuit applies to almost any operational amplifier and the power supply must be symmetrical.
With this circuit it is possible to fire an SCR from the light that falls on a phototransistor. The circuit...
This simple circuit can use any general-purpose transistor. The power supply must be isolated. The circuit...
Using a sensor from the time, this circuit was found in the 1992 Radio Electronics Handbook...