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Recently I bought this motor and I want to control it with an Arduino. I read that I can drive the motor with a H-Bridge with TIP120 Darlington transistors, but the problem is that voltage in the motor and the arduino should be the same. This is not possible since the motor should operate at 12 VDC and the arduino is 5V. There is anyway I can drive that motor with the arduino. I just want to rotate the motor in both directions clockwise and counterclockwise at the default constant speed of 6 RPM.

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  • \$\begingroup\$ Welcome to EE.SE, but there are tens of thousands of examples of how to do this on the web already. Do some research and come back if there is something you don't understand. \$\endgroup\$
    – Transistor
    Apr 7, 2016 at 18:49

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You can use various H-bridges available in the market for rotating the motor either ways! However, you can also make one yourself!(We usually design them on our own so as to meet the current requirements of the specific motors(due to varying loads). You could use an opto-coupler/opto-isolator as in the input from the arduino. Thereafter, these outputs can be used to switch the relays(of requred current rating) whose coils are connected between Power(12V,in your case) and Ground.

If you want to rotate the motors in both the direction, use 2 optos! You can also use a MOS if you need to control the speed of the motor(PWM). Make sure that the relay requirements and optos are chosen depending on the current!

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  • \$\begingroup\$ I found this example. Do you think this one is suitable for my motor? arduino-for-beginners.blogspot.com/2011/03/… \$\endgroup\$
    – Pepe Chola
    Apr 7, 2016 at 19:30
  • \$\begingroup\$ 5 amps will be a challenge for the readily available affordable bridges. \$\endgroup\$ Apr 8, 2016 at 2:12
  • \$\begingroup\$ @PepeChola Yes the design style is apt for your needs. However, you need to consider the ratings of the device since your motor has a current rating of 5amps. Relays usually are tolerant to 5Amps. You need to specifically check the current rating of optos and Mos(in case u r using PWM) \$\endgroup\$ Apr 14, 2016 at 15:33
  • \$\begingroup\$ @ChrisStratton That is the reason I recommended designing a customised bridge \$\endgroup\$ Apr 14, 2016 at 15:34
  • \$\begingroup\$ Designing a custom semiconductor H bridge tends to be a relatively involved project, with the potential for a number of "exciting" learning mistakes. If the goal is to learn how to design bridges, great... if the goal is to spin the motor, especially at its ordinary speed, that's probably a long, expensive, and unnecessary diversion. \$\endgroup\$ Apr 14, 2016 at 15:46
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If you only need to turn it at its normal speed, and not pulse-width-modulate the drive, you might consider relays as a cheap and relatively isolated way of accomplishing your task. There are multi-channel optoisolated-drive relay boards widely sold for use with Arduino and other microcontrollers. In selecting one, make sure to read the DC current rating and not the AC current rating, as they may be different.

Semiconductor H-bridges are of course an option, but ones rated for 5 amps tend to be a bit more expensive, and as you noted at least one side of the circuit tends to be in common with the control. One possible approach can actually be to modify the firmware of a speed control intended for a brushless motor in a radio control model, to instead drive a brushed motor bidirectionally - but make sure to find one that doesn't assume rapid switching in how it creates the high side drive voltage, as those that do won't work for a steady "on" in a brushed DC motor.

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