This CMOS 4001 oscillator alternately turns the relay on and off at times set by R2. The circuit is from Electronics Now magazine, June 1995.
An interesting type of sensor for specific applications is the sensor formed by piezoelectric...
This circuit is from Radio Electronics from the 90s. It supplies a voltage between 800 V and 2 000...
This circuit was obtained in a 1989 publication and is quite simple to assemble, but critical in...