Found in a 1924 book by Gernsback, this circuit uses a double variable capacitor, a component not very common at the time. Listening was done on a loudspeaker at the time.
The UAA170 integrated circuit is no longer common in our market. With it it is possible to...
This circuit that emits siren sound can be used in a fire alarm. We found it in an old American...
This double time constant circuit for resistive loads was found in documentation from the 1980s. The...