This circuit was found in a Popular Electronics from the 90's. Its purpose is to detect the ionization of the air. The meter can be replaced by the current scale of an ordinary multimeter.
This amplifier must be supplied with a voltage of 24 V and the resting current is of the order of 4...
This circuit is from a magazine 73 for radio amateurs of the 90s. The circuit generates the high...
This circuit generates quadrature signals in frequency that depend on the 18 pF capacitors. These...