This circuit for the 40 MHz band was published in Radio Electronics magazine in December 1957. Its purpose was to monitor the signals of the Russian satellite launched at 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...