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.
The purpose of this circuit is to maintain the liquid level of a reservoir between two values...
This circuit was found in a Popular Electronics from the 90's. The circuit has gained 10 to 20 dB...
The purpose of this circuit is to find two resistors with very close values for critical...