This sensitive bio-monitoring circuit was found in the December 1984 issue of Radio Electronics magazine. The circuit is powered by a 9 V battery and uses a low-impedance headphone output.
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...