PWM motor noise

Hi all, bought a PWM kit (

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), but put in an IRF840 & a 630V .1uF cap to run a 108VDC (nom) motor with rectified/filtered line voltage (~160VDC). The motor makes a rather loud (pwm) noise when running, is this normal? Any way of quieting it down? Yes, I know I shouldn't be rectifying mains, but this is a test & I'll use a stepdown/ isolation Xformer if & when it's working well. TIA! Bart

Reply to
Bart
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High pitched at low speeds,and it gradually gets higher pitched at faster speeds? Pretty normal.

Reply to
phatty mo

What is the PWM frequency? An IRF840 should be able to switch well above audible frequencies. You might be able to turn the PWM frequency up by changing a resistor or capacitor.

Jon

Reply to
Jon Elson

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