This circuit was obtained from the Encyclopedia of Electronic Circuits volume 5 of 1995. The circuit uses the 4001 CMOS to obtain hysteresis in the sensor feedback.
We found this circuit in a 1960 Sylvania transistor manual. The relay can be 12 V and C1...
The basic siren configuration shown in figure 1 activates a piezoelectric transducer and can be...
One flip-flop of the 4018 can be used as a frequency divider or counter as shown here. Frequency...