Beefing up output of stock Arduino Motor Shield

Development Boards Arduino
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Bought a motor shield…before I measured the current draw of the motors on the power wheels truck I was planning to drive with it…(sigh)…

Each motor draws 3 amps no load. Too much for the stock Arduino motor shield, even at low PWM’s, even with a heat sink, even with a heat sink and fan…(sigh)…heats up and shuts itself down. Measured 230F on the heat sink last night :o

Trying to figure out an easy-ish way to beef up the output, get at least those 3 amps, plus a few for loaded current.

Have a load of each IRF9Z24N P-channel and FQP30N06L N-channel MOSFETs.

Thinking an H-bridge on the motor shield outputs. Ch A+ drives the left side of the bridge, Ch A- drives the right side of the bridge, along with the required pull-up/pull-downs on the gates, and diodes across S & D.

Not sure if the motor shield will drive those FETs hard enough under load.

Going to build it up at any rate.

What will smoke first?

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Disregard…I pulled my head out of my arse…

Built up an H bridge from scratch rather than try to beef up the shield’s output.

Not quite as pretty, but handles a buttload more current and barely warms up the MOSFETs.

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Can you post up a schematic and parts list you used?

Thanks

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Standard H bridge, PWM and DIR control, literally thousands of Google hits…

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Why not add one more? Why do you have to be a dick? Hell at least I was nice about it.

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Not being a dick. I didn’t do anything that 3 bazillion people haven’t done before me. Not to mention that there isn’t a handful of schematics, etc. right here on Sparkfun.

I’ll do this much…

http://lmgtfy.com/?q=h+bridge+circuit

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Are you worried that someone will notice something wrong in your circuit?

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Knock Knock

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First run on the protoboard. Dual motor, bidirectional, logic level 4 wire interface.

Worked well enough, but obviously wires too small. Handled about 10 amps before I noticed some insulation started sagging. MOSFETs were barely warm to the touch.

Second run is in the works…fatter wire, paralleled power MOSFETs, etc.

Good enough for you?