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[DPRG] help needed in h-bridge

Subject: [DPRG] help needed in h-bridge
From: Rick Bickle rbickle at swbell.net
Date: Mon Jul 11 10:29:36 CDT 2005

I believe that this schematic intends for you to connect something to
the bases of the transistors. Be sure to put some resistance in series
with the transistor bases to limit the base current.

This particular schematic looks to have a problem. I believe that the
NPN and PNP transistors are transposed here. Put the NPN transistors at
the bottom, and the PNP transistors at the top for better function.
Remember that for an NPN BJT, the emitter voltage cannot be higher than
the base voltage - 0.7V. For a PNP BJT, the emitter voltage cannot be
lower than the base voltage + 0.7. Therefore it is more helpful to have
the NPN transistors sink power and the PNP transistors source power.


-----Original Message-----
From: dprglist-bounces at dprg.org [mailto:dprglist-bounces at dprg.org] On
Behalf Of Horng Woei Chang
Sent: Monday, July 11, 2005 12:21 AM
To: dprglist at dprg.org
Subject: [DPRG] help needed in h-bridge


     As i seen H-bridge tutorials in this web, the difference is the
base is not connected but in my case the base is connected , so i would
like to ask if this H-bridge is working ,the picture is attached, and
what if we vice-versa the polarity.


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