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smoothing circuit design

B

BigBadger

Jan 1, 1970
0
Hi,
I'm building a Pulse Width Modulated fan speed controller to conrol a noisy
high speed cooling fan in my PC. I'm following this article:
http://www.bit-tech.net/article/51/ It uses a Micrel MIC502 chip.
One thing about the design bothers me: the pulsing output disables the fans
built in speed monitoring function.
I would have thought it would be possible to build some sort of smoothing
circuitry to get rid of these pulses. I would guess such a circuit would
consist of capacitors and possible a torroid, however I've no idea how to go
about sizing the components. The output would be 0 - 12V and the pulse
frequency 30Hz.
Any advice gratefully received.

thanks
 
W

wave_man

Jan 1, 1970
0
Sounds like you want to integrate the output of the PWM with a low impedance
RC filter that has low a ESR cap.

JF
 
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