Found in a 1990s American technical brochure, this circuit is intended for alarms that use as photodiode sensors. The circuit has a frequency response of up to 20 kHz. The gain is 40 dB.
We found this circuit in Popular Electronics from 1992. Time is given by C1. The circuit provides an...
A Popular Electronics from the 90's suggests this circuit that is based on a low voltage...
The frequency of a 555 oscillator depends on the capacitance of capacitor C. We can take advantage of...