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 circuit is a handset receiver that picks up the signal emitted by a coil under the rug or...
Voltage comparators, such as those in the LM139/239/339 series, consist of devices that can be...
When the AC Power line fails, the transistors in this circuit are biased to conduce the current to...