This simple injector and signal follower employs a high impedance headset. Transistors can be of general use. The circuit is from old American documentation.
This circuit can be powered by 2 or 3 small batteries. The resistor can have values between 220...
These circuits from a May 1994 Electronics Now take advantage of the noise from the junctions of...
This network can be used in a sound project to control the tone. The circuit is from an...