The indicator for this circuit is a 0 to 1 mA milliammeter. The operational is from the 70s, when the circuit was published. Modern equivalent can be used.
This circuit fires at the touch of a sensor, passing its output from high to low in a time given by...
This circuit was found in a 1967 US publication. In it we have the implementation of a ring...
The strength of an audio signal can be controlled by touching sensors. Keeping the finger in...