The integrated circuit used in this circuit from a 1987 documentation is no longer common today. This circuit can generate a multitude of different sounds and this circuit is an example of application.
We found this MW radio in a 1957 Raytheon publication. The transistors can be modern equivalent types...
This circuit has no lock, but it has a very low consumption feature in the standby condition. We...
This circuit is from a Popular Electronics from the 90s. It uses an opto-coupler with SCR directly...