This very low frequency amplifier has a gain of 1,000 and was found in a 1967 documentation. The circuit is suitable for detecting explosions, distant echoes and seismic vibrations.
This circuit is from an American documentation about filters. The operational amplifiers are 741...
This circuit was found in the November 1992 Radio Electronics magazine. The resistor in series with...
When the switch S1 is pressed for a moment, the motor receives the voltage of B1 more, adding to...