Found in the May 1971 Radio Electronics magazine, this is the circuit for a commercial high-impedance instrument. The circuit uses 4 transistors and is powered by 2 9 V batteries.
This circuit was found in a 1977 Radio Shack documentation. The unijunction transistor can be...
Other series amplifiers such as the MC3301, MC3401 and LM2900 can be used on this circuit. We...
This circuit offers excellent sound quality for headphones of 150 ohms or more. The circuit was...