AIR VOLUME DISPLAY DEVICE FOR BLOWER

PURPOSE: To easily adjust blowing quantity by previously setting up a rotational frequency pattern from low speed rotation up to high speed rotation, rotating a rotor for a motor at optional rotational frequency-in accordance with the pattern range and displaying the rotational frequency. CONSTITUTION: The rate of ON and OFF time of a power transistor QY in a switching circuit 13 is properly changed by a pulse signal outputted by the arithmetic processing of a signal for detecting the rotor position of the motor M and the previously set rotational frequency pattern to optionally change the rotational frequency of the rotor of the motor M. The rotational frequency is displayed as an analog value by light emitting diodes (a) to (g) in a display circuit 41. Consequently user's required air capacity can easily be known and the required air capacity can be accurately controlled on the display means.