This circuit was found in an English documentation from the 90s. It uses a PLL CMOS 4046 and is powered by a 9 V battery. The sensors are two electrodes that must be held by the person.
This circuit is from the 1990 Motorola Linear Databook. The integrated circuit used is the LF355,...
This high impedance amplifier is from 1985 documentation by General Electronic. The amplifier with...
Based on the TCA6600 or TCA5500 this circuit was found in a 90’s European documentation. The...