This circuit was published in an article in Radio Electronics magazine in October 1988. It uses components that are still common today, except for the sensor, which is a special type from that time.
This didactic circuit was found in a 2001 documentation. It presents the result of programming in binary...
This VFO circuit generates signals from 2 Hz to 50 Hz. We found it in Popular Electronics from...
This circuit can be used as a buzzer from 3 different locations, allowing you to identify where it went...