Abstract: The present invention provides a central frequency adjustment device and adjustable inductor layout; wherein, the central frequency adjustment device is applied in an inductor/capacitor tank (LC tank) for adjusting the central frequency of the LC tank. The device comprises a first inductor with a first end and a second end; a second inductor with one end coupled with the second end of the first inductor; and, a first trimmable wire connected to the first inductor in parallel and to the second inductor in series, which adjusts the central frequency by cutting off the first trimmable wire.

Abstract: A musical keyboard having keys which carry metal spoilers that alter the resonance characteristics of tank circuits associated with the keys as the keys move toward and away from the inductance coils of the tank circuits. The tank circuits are connected sequentially to a frequency sensing circuit which develops indications of key positions by sensing the resonance frequency of each tank circuit.

Abstract: A VHF television tuner for selection of a broadcasting television signal through mechanical switching selection of inductance coils, comprising; a tuner casing; a mechanical channel selection switch arrangement provided in said casing and including a rotatably mounted channel selection shaft for selection of inductance coils by rotation of said shaft; a radio frequency amplifier operatively coupled to the selected inductance coils for selectively amplifying a desired radio frequency signal; a local oscillator operatively coupled to said selected inductance coils for providing a local oscillation frequency signal, the frequency of which is different by a given frequency difference from said selectively amplified radio frequency signal; a mixer responsive to the radio frequency signal from said radio frequency amplifier and the local oscillation frequency signal from said local oscillator for providing an intermediate frequency signal; and an intermediate frequency tuned circuit for selectively withdrawing said