With distortion of less than 1 dB from 10 Hz to 20 kHz this circuit was found in the December 1972 issue of Radio Electronics magazine. The amplifier is a type that preceded the 741, the 709.
With this circuit, obtained from an American publication for radio amateurs in 1976, it is...
Small variations in the resistance of the skin of a person holding the electrodes can be detected by...
This circuit was found in a 1967 American documentation. The circuit uses components of the time,...