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 traditional configuration found in a Radio Shack document can use 2N2646. More keys can be...
This is the circuit of a turntable from the 1970s. We found it in a repair article in the December...
Using the CA3018 released at the time, this circuit was found in the August 1970 Radio Electronics...