With distortion of less than 1 dB from 10 Hz to 20 kHz this circuit was found in the December 1972 issue of Radio Electronics magazine. The amplifier is a type that preceded the 741, the 709.
The figure shows how to control the blinking of a 5 V blinking LED with an LDR. The LED only...
Suggested by Maxim in documentation from the 90s, this circuit has its response curve given next to...
This circuit is from a 1965 General Electric publication. It uses a thermistor to fire a reed...