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Message-ID:	<4EF23C5C.70108@ecosensory.com>
Date:	Wed, 21 Dec 2011 14:06:52 -0600
From:	John Griessen <john AT ecosensory DOT com>
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To:	geda-user AT delorie DOT com
Subject:	Re: [geda-user] Design suggestions...
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Reply-To:	geda-user AT delorie DOT com

On 12/21/2011 01:55 PM, John Doty wrote:
> But if you turn the FET fully on, it will charge the cap up to the supply voltage, defeating the PWM.

Yes.  I was thinking of an R-C at the motor, but had Rob's meaning confused.

>
> Usually with PWM you use inductance (possibly intrinsic to the thing you're driving)

to smooth the current, and let the voltage swing rail to rail, with larger excursions prevented by diodes.

Yes, the R in series with the motor was just a goofy idea.  And the body diodes will have to take any
voltage from the motor inductance.  So there's no short cut around calculating the motor
inductance kick, or experimenting to see how hot your drivers get to be sure they are not burning up.

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