This circuit is from an American 80's documentation. The integrated circuit is from the time and the sensor consists of a smoke chamber measuring its transparency change.
This instrument, based on a 555, measures frequencies up to 1 kHz, but its scale can be modified by...
This circuit is from a Japanese publication in 1967. The circuit uses a Geiger-Muller valve and...
This is one of the many hysteresis comparator circuits the reader may find in this section and on this...