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Mosfet noob

BobK

Jan 5, 2010
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Several reasons:

1. Motors do not run well on lowered voltage. It is better to control the speed by using PWM which varies the % of time the full voltage is applied.

2. MOSFETS are not good as linear devices, your control voltage would be a small range.

3. You are wasting energy and heating up the MOSFET if it is in the linear region. PWM avoids this.

Bob
 

MrEE

Apr 13, 2012
84
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Apr 13, 2012
Messages
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PWM in itself is a form of DAC, but instead of converting a binary value, you (the motor in this case) are converting duty cycle to an average voltage that the load will see. A PWM switch ( the MOSFET in this case) must switch from fully on to fully off and spend a minimal time in between.
 
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