Using a 4046 PLL, which is uncommon today, this circuit was found in the October 1994 issue of Electronics Now magazine. The circuit can be modified by changing the capacitor.
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,...