| 摘要 |
PURPOSE:To form a speed detector of simplified circuits by separating the output of a speed generator with a photocoupler, and using a comparator for an oscillation circuit and a waveform shaping circuit. CONSTITUTION:While a speed generator is not in operation, a constant electric current flows through its winding TG to a light emitting diode Pd of a photocoupler PC, and a photodetecting transistor PT is on. Electricity is charged to a capacitor C; at the same time, the capacitor C is discharged periodically by a transistor Tr3 for electric discharging connected to the output terminal of a comparator COMP, and the comparator COMP makes oscillation motion. When the speed generator begins to revolve, the oscillation phenomenon is broken, and the comparator COMP changes over to a waveform shaping circuit which converts a sine wave input to a square wave output. |
