This circuit uses a crystal phone and can be built with more modern transistors like the BC548. The original circuit is from a 1979 publication and is powered with only two AA or AAA batteries.
This circuit with several outputs was found in old American documentation. It can be applied to...
The circuit shown in the figure generates rectangular signals up to 1 MHz with three types of...
This shield circuit can serve as a basis for a digital mixer or simply for a switch without noise...