Hi Howard
Thanks for the tip.
I am still looking into it, so I will probably try it at some stage to
see how well it works and then improve it to my needs. 
I definitely like the idea of braking the motor this way.
If you have any links for this subject can you let me know, as I would
like to learn a bit more about the theory behind it.
Best regards
		Luis



-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of Howard Winter
Sent: 14 July 2005 09:45
To: Microcontroller discussion list - Public.
Subject: RE: [OT] R/C servos control

Luis,

On Thu, 14 Jul 2005 08:56:54 +0100, Luis Moreira wrote:

>...<
> When I looked at ways to control a DC motor one
> of the ways to brake it was to turn on both bottom or top transistors
on
> the H bridge and that should short the motor and brake it. Any views
on
> that technique welcomed.

Regenerative braking certainly works - I have a couple of
battery-powered drills, and when you release the 
trigger they stop as if the motor has seized!  The largest, an 18V
DeWalt, is heavy enough and stops so fast 
that the torque reaction gives the thing a kick that you can't stop by
hand.  You could look at providing a 
reverse-voltage to try to stop if more quickly, but I think the effort
and complexity isn't worth the tiny 
improvement you might get.

The only thing to watch is the rating of the transistors - you need to
be generous when it comes to this sort 
of thing because they will see some impressive current spikes.

Cheers,


Howard Winter
St.Albans, England


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