This circuit appeared in Amateur Radio Today in an issue and was found in a 1995 issue. The circuit is for the AM band up to 3 MHz. The transistors are general-purpose.
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...