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Driving a ride on toy car motor

Hi folks,

As part of a project I'm building I need to create a rotating platform and I recently salvaged a DC motor and its gear train from a ride on toy car, so I thought if it can scoot a child around it should have enough torque for this application. The problem is that I'm not sure how to drive it.

The platform is 80cm diameter with some stuff on it that weight around 2Kg (distributed around the rim of the platform). It doesn't need to spin fast. In fact it's better if it spins slowly. It also spins quite infrequently, perhaps one full rotation once per minute then it stops until the next one. It also should spin in only one direction. It's a stationary machine, so I won't power it from batteries but from a PSU.

The motor has no useful markings on the case except a "Johnson" logo and a code that can't be found anywhere in the Johnson's web site or on google. But with some research I figured the motor should be this one:

file:///home/nerochiaro/projects/stickman/rideoncar/HC683LG-011-metric.pdf 

What troubles me about it is the stall current of 60A. I've never worked with currents that high, and I'm not sure what I can use to drive it. All the motor drivers I've built so far have been based on L298N (or TIP120 for things that don't need direction control), but these components are not even in the ballpark for handling that kind of current.

I thought about using a relay but I'm not sure which component can be a good choice, assuming a relay is the way to go.

How would you go about driving it, possibly without spending a fortune ? And alternatively, whay would be a good replacement motor for this application ?

Thanks in advance for any advice.

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If it only needs to spin in one direction wouldn't it be the easiest to use a big mosfet? Let the microcontroller switch a transistor that controls the mosfet if you can't find a logic level mosfet that can handle the amps. And use a pwm output to control the transistor/mosfet.

Seems like a good idea, I hadn't considered these before. While searching for this I stumbled upon this tutorial: http://www.hobbytronics.co.uk/arduino-tutorial9-power , which links to a mosfet that can apparently handle 80A and be driven by TTL logic.

From that page it seems to say I can just connect the mosfet to the motor and the microcontroller without an additional transistor. Does it make any sense ?

Also, if I go that way, do I need a freewheel diode to protect from back EMF or is the MOSFET already protected internally from that ?

(clearly totally new to mosfets if it wasn't clear already :))

If you use the same 95N2LH5 from that HobbyTronics link then you can drive it directly from a microcontroller. With 4-5V across the gate you'll be able to easily put 60A through it.

The 95N2LH5 also has an internal diode that can survive a 320A pulse (!) so you are well covered for back EMF.

Heatsink is a must, but any FET with similar stats will be a good match for your project.

 

I found a component that seems quite similar and readily available where I am, the STP80NF03L-04. If I read the specs correctly it has the same very high back EMF protection as the 95N2LH5.

I'll try to order a couple and see how it goes. Thanks for the help !

 

A DPDT Relay can act as an always on H-Bridge, and pairing it with SPST can give you on/off control.  The problem is going to be finding one that can handle 60A through the throws but only takes 5v to trigger (assuming you're using a μController.)  Lots of larger bots use wheelchair motors but I don't know what the usual stall current is on those.  Some have suggested using BIG transistors to make Tilden-style H-bridges for applications like this.  If you go that route, use one of the smoke-proof designs.