In the figure we have a good rectangular signals generator with several frequency bands. The circuit is based on old logic but can be implemented with modern equivalents.
We found this sensitive moisture detector in an old documentation. The circuit uses a common JFET,...
This circuit, with the assembly in a contact matrix, was found in a publication from the 90s. The...
This modulator circuit for transmitters was found in American documentation from 1964. It can be...