diode bridge as H bridge?

Keep in mind that the speed of the diodes must keep up with the speed of the switching transistors in the H-bridge driver. Slow diodes will make the driver run hotter.

That said, why do you need 10+ amp diodes for a driver rated for no more than 2 amps? I would think that 2 or 3 amp rated Schottky diodes would make a good bridge rectifier for this driver. E.g. 1N5820 through 1N5822.

The H bridge is actually inside the L293. I guess the diodes are meant to protect the L293 during braking of the motor. Part of the mechanical energy is dissipated in the diodes. You might be able to use lighter diodes (2A).

I think it is safe just to try your idea.

I put up the L293B as an example of a H bridge.

I am actually building a H bridge which needs to switch 12V @ 10A. I was just using the L293B to drive a 2N3055 for a while as I hadn't been able to goto the shop to get some other transistors to drive them. I am going to get BC639 to drive the 2N3055.

John P> > Hi,

I think you might consider 4 of 95SQ015, 9 amp 15 volt Schottkys, with a peak current rating of 2900 amps for 5 us, about $2 each at Digikey.

A bridge rectifier would indeed do the job as you've drawn it but I'm not sure that the diodes are perhaps as fast as you might like for this application.

You don't need a high current rating, the diodes aren't normally conducting.

Can you get the MUR420 ? That would be ideal for this job.

Graham

that the diodes are perhaps as fast as

Actually, after looking more, you don't need an ultra-fast part there.

How about 1N5402/4 ?

Graham