Suggested by a 1990 book for amateurs, this circuit makes use of an integrated component that is not common today. It converts signals from one band to signals in a 10.7 MHz band below.
This simple circuit causes an LED to light up when the battery voltage drops below the voltage set in the...
Obtained from a 1967 documentation, this circuit uses transistors from the time. The galvanometer can be a...
The figure shows how to implement an alarm buzzer in an LM3914 to warn about crossing the scale...