Cross the bridge

Hi all,

Does anybody know of any H bridge circuit (pos. MOSFET) to drive a 12 v high amperage motor , say a starter motor . Could you possible include some protection circuits , as this is going to work in an overdamped system , which might lead to high back-emf's , spikes.

P.S: Can a started motor be reversed like other DC motors. (interchanging terminals)

Thanks

dreamproject said:

Hi all,

Does anybody know of any H bridge circuit (pos. MOSFET) to drive a 12 v high amperage motor , say a starter motor . Could you possible include some protection circuits , as this is going to work in an overdamped system , which might lead to high back-emf's , spikes.

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You're talking large expensive (VERY! expensive) controllers, car starter motors can take 100's of amps. In the Robot War's field starter motors are considered very poor choices, although there have been a number of fairly sucessful robots that used them - but, as far as I know, they only used relays to switch the motors ON and OFF, no H Bridge controllers.

There are a number of manufacturers that make speed controllers, 4QD are one of them https://www.4qd.co.uk/ - but I don't know if anyone makes controllers suitable for starter motors, they aren't really a very good motor!.

P.S: Can a started motor be reversed like other DC motors. (interchanging terminals)

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Not without modification, the field and rotor windings are connected in series, so it rotates the same way even if you reverse the power to it. You need to reverse just one of the windings - probably the field winding would be easiest?.

Nigel, have you ever participated in Robot Wars???

samcheetah said:

Nigel, have you ever participated in Robot Wars???

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No, but I've always fancied a go :lol:

ive also been a fan of Robot Wars. but i havent been getting much time lately to watch TV. i remember the last show i saw was when Chaos II won the finals for the second time.

how about an electric wheelchair motor geared to the steering column ??