Asked — Edited

Can A Single Fisher Price Motor Be Controlled With An Ez B?

I am very new to EZ Robot. I have an EZ Robot kit. I'd like to hack an old toy a Fisher price ride on car that is powered by a single motor. I think 6 v. Would I need an Hbridge for this? If so which one? Or is there another way to connect and control this motor?
I'm considering taking the handle bars off and glue/screw a servo to the steering mount so I could control the steering with Ez-B. I think this toy could be a great chassis for building a larger robotic form factor. I can provide a photo if needed. Any thoughts or assistance would be greatly appreciated. Thanks, Keri


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You would need an H-Bridge. Hard to say which one without specs on the motor, but most small toy or hobby motors can be driven by the 2.5A H-Bridge sold by EZ-Robot (note: this is a commonly available controller, on-line, at Microcenter if you have one near you, or many hobby shops. No need to spend EZ-Robot shipping unless you have other stuff you need to order from them. They offer this as a courtesy for their customers for one-stop shopping, but they don't manufacture it, so you aren't taking money from their pocket if you source it locally).

If you have a multi-meter, you can measure the amps drawn by the motor at stall (run the motor, then grab the wheel to prevent it from turning momentarily an see how many amps it draws. Don't do it for long so you don't burn out the motor). You'll want a motor controller rated a bit higher than the amps at stall of your motor (20% is a good rule of thumb).



Thanks Alan for your quick response. Is there a tutorial online with how to solder or wire this Hbridge to the EzB? I do not have any experience with this type of thing. I don't want to destroy any of my Ezb components, the Hbridge or the motor. LOL! Also, do you think the Ez b servo has enough strength to "turn" the steering mechanism if I mount it directly to it?

Thanks so much! Keri




Also, do you think the Ez b servo has enough strength to "turn" the steering mechanism if I mount it directly to it?
Most definitely .... yes... If anything the ez robot HDD servo would break the toy first...


Will this work? driver: L298N; driver power supply: + 5 V to + 35 V; driver output current (max.): 2A; logic power output Vss: +5 V to +7 V (internal supply +5 V); logic current: 0-36 mA; controlling level: low -0.3 V to 1.5 V, high: 2.3 V-Vss; enable signal level: low -0.3 V to 1.5 V, high: 2.3 V-Vss; max. current: 25 W Found this t our local microcenter. Thanks


That is very similar to the EZ-B one (2amps instead of 2.5, but same controller so will work the same).

Again, the key is how many amps the motor draws. If it draws more than 2 amps, you will see magic blue smoke.



That is a 4 amp H-Bridge, but you say the toy outputs 4 amp hours. That sounds like the battery rating, not what the motor draws. A 4 amp hour battery can put out a lot more than 4 amps. 4 amp hours means that it will last for 1 hour while having 4 amps drawn from it. It would last 1/2 hour having 8 amps drawn from it, less the more power you draw. You really need to know what the motors draw to make the correct decision.

I just realized you said this was a rideable toy. Is it a Fisher Price Powerwheels? I think those motors are closer to 20 amps. (I know the fuse is either 20 or 25 amps)

That also may change the suggestion that you could steer it with an HD servo. It should be OK just driving the thing on its own, but if you put a child on board, I am not sure if the servos could handle turning it under full weight. They are strong, but there are certainly limits.



(What Alan last said.) Right, guys, remember he is talking about the Powerwheels cars for children to drive and ride inside! Not a toy RC car.

Josh did a Power Wheels conversion here

And so did Robotz