Using 4 tubes, this 1924 receiver combines new technologies as an intermediate frequency stage that was already beginning to appear. Listening is via phone and battery power.
This circuit was found in a 1989 documentation. The circuit directly controls a power load by the use...
This small telephone transmitter uses a telephone capsule as a microphone. The L1 coil has 4 to 5...
This emergency light circuit does not include a battery charger or an intelligent system to...