This simple circuit with a 5V regulator was found in an American documentation from the 90's. The output voltage is adjusted in a trimpot.
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...