Re: TI-H: H-bridge


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Re: TI-H: H-bridge




An H-Bridge is a fairly simple driver circuit. I use it for driving motors on
my robots. You have 4 transistors arranged in an "H" form, with the motor
being the horizontal line.

the (+) connect's to the emmiter of the "top" two transistors, which are NPN,
and the (-) connects to the emmitters of the "bottom" two transistors, which
are PNP. The collectors oth the right transistors (one NPN and one PNP)
connect to one lead of a DC motor, and the other two transistor's collectors
attach to the other motor lead.

The Base's of the right and left transistors are also joined (like the motors
are, but on the base instead of the collector.

when both lines are low, the two sides are at the same state (I forget if it's
(+) or (-), but it's one, and I'm assuming (-) for now). Following the (-)
example, it'd be like attaching the two wires of the motor to (-). There is no
completed circuit. the motor is off. Same if both are high. they are then both
(+), like attaching both leads to the (+) terminal of a battery.

now, if you put one high and leave the other low, it activates the transistors
and they invert. The high line causes the (-) transistor to turn off and the
(+) to turn on. the motor spins in one direction.

If you take that line low and pull the other one high, then the motor spins
the opposite way, cause the (+) is on the opposite side as before, and the low
line gives it a (-) completing the circuit in the reverse polarity as before.

It's a simple circuit and it has done an excelent job for me!!!



Larry G Currie wrote:
> 
> Very simply andor shortly, can anyone say what an H-bridge is?
> ~Larry C
> Larry1492@juno.com
> 
> Hey Grant =>"What was in Monica's pocket?  A wad of Bill's"  -John
> Henson; Star of Talk Soup
> 
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-- 


Richard Piotter
richfile@prairie.lakes.com

The Richfiles TI Hardware and BASIC web page:
http://www.geocities.com/SiliconValley/Lakes/5081/Richfiles.html


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