This circuit is from a 1967 RCA documentation. Components can be replaced with modern equivalents. The circuit trips with signals from sensors connected to its input. The circuit needs at least 1 V signals at the input.
This amplifier or stethoscope with headphone output and using a crystal microphone was found in a...
Found in a 90s American documentation, this circuit mimics the Enterprise warning signal from the...
September 2016 - Supercapacitors of 10F to 100F in 3 V from Eaton can now be purchased from Mouser...