Using the 741 this basic circuit was found in the November 1973 Radio Electronics magazine. The power supply must be symmetrical. The components can be recalculated for other frequencies.
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...