Using an integrated circuit that was available at the time, this circuit produces animal sounds such as mooing, rooster crowing, etc. The circuit is from a March 1997 Electronics Now magazine.
This configuration, which produces a rectangular signal compatible with CMOS and TTL logic, was...
We found this circuit in a 1977 Radio Shack brochure. Transistors can be the most modern BC548 for NPN...
The basic idea of this circuit is to convert the indication of a magnetic sensor to an audio tone...