Re: transistors instead of diodes?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Jan Wagner <jwagner@xxxxxxxxx>


On Wed, 23 Mar 2005, Tesla list wrote:
> Original poster: "Jolyon Cox" <jolyon@xxxxxxxxxxxxxxxxxxxxxxxx>
> I am wondering if in place of fast-recovery diode it would be possible to 
> use a second transistor in anti-parallel with each transistor of the 
> H-bridge; the latter switching on at the same time as the former but 
> switching off a short period later to allow any spikes to be returned to 
> the supply rails.

I think the "diode replacement" transistor would not especially like the 
reverse voltage (full rails V) placed across it, which will happen in a lot 
of different scenarios... You could add a fast recovery diode in series to 
protect against the reverse voltage, but that kind of defeats what you were 
trying to achieve in the first place ;-)

cheers,
 - Jan