The configuration shown was found in the October 1974 Radio Electronics magazine. The integrated circuit used is the CD4001 and the power supply depends on the application.
This circuit reinforces signals in a frequency range between 1500 and 2000 Hz for use in...
When a small air current reaches the piezoelectric sensor, a small audio signal is generated and...
This circuit is from a Poptronics, American magazine from August 2000. The circuit can be...