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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