[chbot] H-Bridge (was Re: Sensor Information)

[Charles Manning]

I would not put the L298 high on the list because it is a common collector
device, just like the L293.

The internal configuration of these devices means that the output voltage
does not swing all the way to the rail and you lose approx 1.5 to 2 volts in
the driver chip. This turns into heat, but also means that your motor does
not get driven as hard as it should meaning that it does not get enough
Weetbix to win that Sumo competition. That is perhaps not too much of an
issue when you're using 12V or more input, but obviously throwing away 1.5V
or so is bad news for low voltage systems.

Many modern HBridge designs are "rail to rail" and do not suffer this
problem.



On Wed, Mar 25, 2009 at 3:54 PM, Andrew Errington <
a.errington at lancaster.ac.uk> wrote:

> I actually like this design:
>
> http://www.mcmanis.com/chuck/Robotics/tutorial/h-bridge/bjt-circuit.html
>
> Because the opto circuit is very elegant (it combines optical isolation
> with 'smoke-free' logic).  I've never built one as I was not able to find
> a fast enough opto-isolator to do high-frequency PWM.   It may be that
> that is a non-issue however.
>
> Good luck with whatever design you choose.
>
> Andrew
>
>
> _______________________________________________
> Chchrobotics mailing list Chchrobotics at lists.linuxnut.co.nz
> http://lists.ourshack.com/mailman/listinfo/chchrobotics
> web site: http://kiwibots.org
> When replying, please edit your Subject line to reflect new content.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.ourshack.com/pipermail/chchrobotics/attachments/20090325/079cc06e/attachment.htm