| 摘要 |
PURPOSE: A circuit for detecting wire/wireless mode and selecting the power of a wire/wireless keyboard is provided to automatically detect wire/wireless mode, to automatically select and supply the power, to achieve the simplification of control, and to enhance the reliability of power selection. CONSTITUTION: The circuit includes a wire/wireless mode detection circuit(38) and power selection circuit(39). The wire/wireless mode detection circuit comprises a AC inhibiting coil(L1) connecting to the power line of main body connector(37), a voltage detection resistance(R1) to detect the voltage through the DC inhibiting coil, and a switching transistor(Q1) connecting the base to the voltage detection resistance through another resistance, connecting a collector to the output terminal of power selection circuit through a resistance, connecting an emitter to the ground, and connecting an output terminal of collector to the input terminal of controller. The power selection circuit comprises a first diode(D1) connecting an anode to the voltage detection resistance, a FET(field Effect Transistor,Q2) connecting the collector to the cathode of first diode, connecting the base to a connection point between the voltage detection resistance and NAND gate.
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