This circuit has a visual indication of activation and is suitable for people with hearing impairments. The circuit was found in the March 1974 issue of Radio Electronics magazine.
This circuit was found in a 90s Radio Electronics. It is intended to amplify the sound channel of...
This circuit uses a 4020 counter that divides the frequency up to 210, being found in a former...
This circuit was found in a Radio Electronics magazine from May 1967. The circuit has the time...