This 4-transistor amplifier can work from 4.5 or 6 V power supplies. We found it in a Mullard transistors manual from 1960. The transistors are from the time.
Based on the CA3140 IC, this circuit was found in the June 1986 issue of Radio Electronics....
When sensors X1 and X2 stop driving by the dryness of the monitored location, the oscillator...
This circuit works directly connected to the network and special care must be taken with its...