This circuit was published in an article in Electronics Now magazine in October 1995. The circuit includes a power supply. The power transistors are equivalent.
We find this microphone voice effect in 1992 documentation. The vibration of the relay contacts...
We can also use the 4011 on this CMOS circuit that makes use of a crystal headset. The power...
We found this circuit in documentation from the 1980s. The integrated circuit used is uncommon today,...