Patent ID: 6707385
Filing Date: 2004-03-16
Classification: G06F

Abstract:
A simple alarm circuitry connected to a driving circuit of a DC motor for outputting a motor rotation speed alarm signal, comprising:an input node jointly connected to a preset voltage power supply with the driving circuit of the DC motor; a connection node electrically connected to the driving circuit of the DC motor; a ground node jointly connected to the ground with the driving circuit of the DC motor; a comparison circuit electrically and respectively connected to the input node, the connection node and the ground node to provide a preset voltage smaller than the voltage power supply; and a signal generator connecting electrically between the comparison circuit and the ground node to output the alarm signal; wherein a floating voltage is generated between the driving circuit and the ground node when the rotation speed of the DC motor changes during operation, the signal generator outputting the alarm signal to indicate the DC motor operated in a normal operating condition when the floating voltage is smaller than the preset voltage of the comparison circuit; the signal generator outputting the alarm signal to indicate the DC motor operated in an abnormal operating condition when the floating voltage is greater than the preset voltage of the comparison circuit.