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.
We found this circuit in an old American documentation. Accuracy has 0.02% error and 0.003%...
September 2016 - Mouser Electronics is offering the new oscillator clock PECL series PE55K of the...
Found in a Philips documentation from 1968, this circuit detects the trimpot set input voltage....