This circuit, for frequencies up to 100 kHz, was found in American documentation from 1970. The circuit can serve as a reference for projects with modern equivalent components.
This rain, flood or leak sensor was found in a 90s Popular Electronics. All the components used are...
This circuit came out in an English publication from 1973, but it can be easily assembled using a...
This circuit has a two-position tone control providing a power that reaches 5 W. The supply...