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[DPRG] Please Clarify when to use npn or pnp transistors (fwd )

Subject: [DPRG] Please Clarify when to use npn or pnp transistors (fwd )
From: Dan Miner miner at centtech.com
Date: Wed Jul 11 15:10:24 CDT 2001

I think you have PNP and NPN backwards in your description.

> -----Original Message-----
> From: Robert L. Jordan [mailto:rljordan at airmail.net]
> Sent: Wednesday, July 11, 2001 2:33 PM
> To: rich_demartile at prodigy.net
> Cc: Dallas Personal Robotics Group
> Subject: Re: [DPRG] Please Clarify when to use npn or pnp transistors
> (fwd)
> 
> 
> Rich,
> 
> I have an opinion but not much knowledge.
> I use NPN to switch Positive ("source DC")
> The collector is connected to +DC
> 
> I use PNP to switch Negative (Ground)("Sink power")
> The collector is connected to -DC (gorund, common)
> 
> In an HBridge you can use "P Channel Mosefts" to switch Positive 
> and "N Channel Mosfets" to switch ground. The P channel requires a 
> voltage of about 7 volts above the source voltage to turn it on. (I 
> think) You can use N channel Mosfets on the positive side too, but 
> I'm not sure the pros and cons.
> 
> I hope to hear better answers to your question from others! 
> 
> Bob Jordan
> 
> Eric Yundt <eric at facetcorp.com> said:
> 
> > DPRG,
> > 
> > Anyone up for helping Rich?  Jim is no longer on the DPRG list
> > and doesn't receive email sent to the "dprg.org" address.
> > 
> > Rich DeMartile wrote:
> > > From: "Rich DeMartile" <rich_demartile at prodigy.net>
> > > To: <jbrown at dprg.org>
> > > Subject: Please Clarify when to use npn or pnp transistors
> > > Date: Wed, 11 Jul 2001 01:16:30 -0700
> > > 
> > > Hello Jim,
> > >     I'm new to this stuff.  I've studied solid state electronics 
> for the
> > > last couple months, built a solar tracking device that works for 
> my
> > > first project, and have a basic understanding of transistor 
> usage.  What
> > > I'd like to get cleared up is...when do you use pnp versus npn
> > > transistors, mosfets etc.  I find lots of information regarding 
> hole
> > > flow versus electron flow, and I notice that sometimes one is 
> used over
> > > the other, but never why.  Looking at your page on H-bridge 
> theory I
> > > finally got my first clue to why pnp is used for ...(sourcing 
> power?).
> > > Could you please spend the time to explain to a layman what's the 
> time
> > > to use one type over another, and maybe some real life examples.  
> I'm
> > > starting to think that where the load is in relationship to the
> > > transistor in a circuit dictates what type you would use.
> > >     My lack of understanding in this area is preventing me from 
> moving
> > > forward into more exotic control schemes.  I've been limited to 
> using
> > > relays so far and they work just fine but...
> > >     Anyway, I can tell you know about these things by how well 
> you write
> > > and explain things.  You can check out my solar tracker at the 
> web site
> > > I just started if you like.
> > > 
> > > http://pages.prodigy.net/rich_demartile/
> > > 
> > > Thanks in advance,
> > > Rich DeMartile
> > > rich_demartile at prodigy.net
> > > 
> > 
> > --
> > Eric
> > _______________________________________________
> > DPRGlist mailing list
> > DPRGlist at dprg.org
> > http://nimon.ncc.com/mailman/listinfo/dprglist
> > 
> 
> 
> 
> -- 
> Robert L. Jordan (Bob)
> www.robotfun.com
> 
> 
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