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 is the commercial circuit for the TRF-44 amplifier sold in Japan in the 1960s. The circuit...
This circuit uses a common cathode display and TTL integrated circuits. We found it in a 2001...
This circuit was found in a 1992 publication, using an operational amplifier not very common...