H Bridge recommendations

Hi,

I have managed to damage two L293D chips recently (I'm still confused how): http://forum.arduino.cc/index.php?topic=269755.0

Can someone recommend me a H-bridge that would be suitable for controlling 2 x 6v DC motors?

Thanks,

Alex

Not without more information on the motors - in particular stall current, but preferably all the information you have that we haven't ;)

What is stall current? This is what I am using: http://www.ebay.co.uk/itm/331127894763?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Alex

Stall current is the current the motor pulls when the motor shaft is forcefully locked in place. On toy motors you see them rotating, then you grab the wheel and you make it stop. You just stalled the motor, the stall current is usually 50%-200% larger then its running current depending on the motor type and design.

I have a guess to your issue. The chip has 2 voltage inputs one is for the chip logic and the other is for the motor voltage. Despite what the spec sheet and other say, I found that the chip logic must be 5V, when I applied more the chip over heated and/or performed improperly.

Make sure the logic voltage is 5V, and then you can use 9V or whatever for your motor voltage.

This is assuming everything else was wired correctly though. Most of the time that chips fail is due to improper wiring.

Stall current is easy, divide the supply voltage by the measured resistance of the motor.

Thanks!

For applications that will reverse the motor, it may be prudent to design for double the stall current as a safety margin (slamming from full ahead to full reverse).

Thanks for the info on stall current.

I have gone for one of these: http://www.ebay.co.uk/itm/like/181333991645?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108&ff19=0

Just going to see how it goes, I may upgrade at a latter date...

Alex

Oh dear, rather than wait for a recommendation you’ve gone and bought another
darlington H-bridge.

Neither the L293 or L298 are suitable for low voltage use, they waste 2.5V of your
supply. A MOSFET H-bridge is what I would have recommended if you had given
us an idea of the stall current.

Having said that the L298 with heatsink will be more robust than an L293D, but you
won’t get full speed from the motors.

Although not the best choice for “this” project, you can make it work but you need to be careful. If you apply more voltage as the source the net voltage across the motor will increase, I’d use a volt meter to determine this before you connect the motor if you can. A little over the motors rating won’t matter much (~10-20%) but larger amounts will result in heat build up and might cause damage to the motor.

Although what they say is correct most of the time, I find they are trying to point out problems more often the trying to solve them.