This circuit was found in 80's Popular Electronics. The components used are common and the number of indication channels (LEDs) can be changed.
This circuit, found in 1980s documentation, produces a rectangular signal of the same frequency as the...
The purpose of this circuit from a 1995 publication. Its purpose is to alert a person when he...
This simple transmitter for the citizen range was obtained in a 1983 publication and has only one...