This amplified speaker is from a Radio Electronics from September 1988. The power integrated circuit is from that time and the other components are still common today.
This circuit uses a 7812 and another regulator integrated circuit that is not very common...
The project is from a 1992 publication, but totally current by the components it uses. The LEDs...
We have a simple and useful circuit found in a 1982 documentation which generates a signal in the...