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Re: [PSUBS-MAILIST] PWM Controllers
Yes, PWM does stand for pulse width modulation. This means that the
voltage is modulated between ground (negative) and positive supply
voltage...Although it doesn't have to work this way...So to get a
0.50 or 50 percent duty cycle, I hold to output high for, say, 10
miliseconds and low (ground or negative) for 10 miliseconds. Because
of the load on the supply, the voltage becomes basically the raw
supply multiplied by the duty cycle in percent: 12V * 0.75 = 9V, If
the load was zero the voltage would be 12V, but "no load" means
"no use", right?
Warren
>
> FYI,
>
> I have said for some time that the downfall of our civilization will be the
> use of acronyms. It is almost getting to point where people can't
> understand each other.
> Is the end of communication the end of civilization??
>
> LOL. (-: ......
>
> I think PWM is "pulse width modulation" ??
>
> The DC motor is turned on and off rapidly to reduce the power going to it
> instead of using as resistor to run at less than full throttle. (though
> electric motors don't actually have throttles)
>
>
>
> Robin Williams does a good bit on it in Good Morning Vietnam.
>
>
> MECHANICAL GUY ,
>
> Jay.
>
>
>
>
>
>
> John Rogers
> <djohnndjinn@yahoo.com> To: personal_submersibles@psubs.org
> Sent by: cc:
> owner-personal_submersible Subject: Re: [PSUBS-MAILIST] PWM Controllers
> s@psubs.org
>
>
> 20/01/2003 07:27 PM
> Please respond to
> personal_submersibles
>
>
>
>
>
>
> FET = field effect transistor
>
>
> SCR = silicon controlled rectifier
>
>
> --John
>
>
> "Dale A. Raby" <publisher@thegreenbayweb.com> wrote:
> Militarese translation:
>
> LT = Lieutenant
> MRE's = Meals Rejected by Ethiopians (US soldiers and sailors eat 'em
> though)
> AWOL = Absent WithOut Leave
> SOL = Shit Outa Luck
>
> Now... I'd kinda like to know what FET's SCR's etc are as well!
>
> On Mon, 2003-01-20 at 19:34, Chris Nugent wrote:
> Would someone mind yelling down to the little people and
> explaining what exactly FET's, SCR's, IGBT's ARE? And perhaps a nod
> in the direction of where one can pick up the basics of what is
> being talked about? My LT told me I had to help with the MRE's
> because the cook was AWOL, and if I don't figure this out I'll be
> SOL and my sub will be DOA.
>
> Thanks,
>
> Nuge
>
> Subscuba@aol.com wrote:
> At least, and a bridge is what I would go with. You would
> probably have to parallel several in each leg of the bridge to
> avoid dissipation problems.
>
> There are a number of ICs on the market to do the drive
> functions. I think ONSEMI has one. You would have to do the
> power stages. Layout of the power stages are the bear.
>
> I would suggest IXYS as a starting vendor for the FETs. I
> think their site is "WWW.IXYS.com" they are not the only
> vendor.
>
> Ken Martindale
>
> One other note on the price issue you brought up,
> though. A
> reversible speed controller requires a FET H bridge,
> which means
> twice the FETs. A forward only could be made for $5.00.
> A good
> reversible would easily hit $10.00.
>
>
>
>
>
> Do you Yahoo!?
> Yahoo! Mail Plus - Powerful. Affordable. Sign up now
>
>
> Dale A. Raby
> Editor/Publisher
> The Green Bay Web
> http://www.thegreenbayweb.com
>
>
>
>
>
> Do you Yahoo!?
> Yahoo! Mail Plus - Powerful. Affordable. Sign up now
>
>
>
>
>
>
>
>
--
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