This simple 1-transistor audio preamplifier appeared in the June 1968 Radio Electronics magazine. The transistor is a general-purpose type of the time. The gain is 14 dB.
The operational amplifier is old. The circuit is from an 80's documentation but can be designed...
This configuration, explored in other applications of this section and website, was found in a 90s...
The sensors can be screens having porous tissue between them. When the water moistens them, the...