insanityhimself
Posts: 4
Joined: Sat Dec 27, 2014 12:29 am

question on motors

Thu Jan 08, 2015 11:01 pm

Theoretically, could I connect a variable resistor with the center set as neutral push forward to go forward and back to go back. Connect that to an rpi connect that to a variable switch connected to say an externally powered motor such as a washing machine motor.

Is this possible?

I have a huge project I want a lever to drive a motor the further I push the lever to go faster, and pull the lever back to go backwards. The motor will be powered separately from the rpi.

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iinnovations
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Re: question on motors

Thu Jan 08, 2015 11:22 pm

You need an h-bridge. They abound on ebay and can easily be controlled from a Pi.

Just make sure to spec your hbridge to your motors properly. The rest is pretty standard stuff.

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Tarcas
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Re: question on motors

Fri Jan 09, 2015 4:17 am

H-bridge is necessary to make a motor go backward, but you might find what you need from a continuous rotation servo, and either a Pi or an Arduino to control it. The Arduino will be easier to make read your variable resistor. Pi will require an ADC (Analog to Digital Converter) to read the value of your resistor; an Arduino will not.

I'm not sure, but if your variable resistor has two poles, one that increases in resistance as the other decreases, you MAY be able to design something resembling an H-bridge that speeds, slows, and reverses a motor as you adjust it. I'm not going to design it for you, since I'm no electronics engineer and it would take me a long time to research, but it might be possible... I'm not sure. You'd have to consult an expert if it isn't already out there.

insanityhimself
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Joined: Sat Dec 27, 2014 12:29 am

Re: question on motors

Fri Jan 09, 2015 10:23 am

Looks like due to funding I have to put this project on the back burner.

PiGraham
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Re: question on motors

Fri Jan 09, 2015 10:28 am

Driving mains AC motors (washing machine motor) is a very different thing to driving small DC motors. Due to high voltages and high torque you should not tinker in ignorance with washing machine motors.

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joan
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Re: question on motors

Fri Jan 09, 2015 10:34 am

PiGraham wrote:Driving mains AC motors (washing machine motor) is a very different thing to driving small DC motors. Due to high voltages and high torque you should not tinker in ignorance with washing machine motors.
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rgrbic
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Re: question on motors

Fri Jan 09, 2015 5:41 pm

don't do that
it is probably asynchronous single-phase motor
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Mark_T
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Re: question on motors

Fri Jan 09, 2015 6:03 pm

There are at least 3 different kinds of washing machine motor, they operate at lethal voltages,
and controlling some sorts is pretty advanced - not a biginner project.

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