Stepper motors I have used before and I also know the basics of how it works. I have make one spin with an arduino by turning a pin on and off with 500 seconds of microdelay. I remember that the higher the delay the slower the motor spins.

With DC motors I just have used them by applying voltage to them.

I found some old battery electric drills on my house. I dissembled them in order to remove the motor.

1) The first drill that I dissembled had this motor:

enter image description here

If I connect a battery to the cables the rotor spins. This is therefore a DC motor and it works great.

2) The second drill had this motor inside. I messed up ripped a board that was connected to the top and I was left with this:

enter image description here

When I ripped the board that was on top I circled in yellow the cables that where attached to it. Is this a stepper motor? It looks like one to me but I think a drill should have a dc motor no? How can I make this motor work? What do you guys recommend?


I forgot to mention that this are connected:

enter image description here

1 - 4

2 - 5

3 - 6

Also I can tell there is a strong magnet inside even when it is not connected.

  • 1
    \$\begingroup\$ @CharlesCowie that's the answer, please make make it so. You can add the fact that the scheme that detects the rotor position is called "commutation" (just like commutation in a brushed DC motor), and it's usually done with hall effect sensors -- in this case, they were probably mounted on the control board. \$\endgroup\$
    – TimWescott
    Apr 20, 2020 at 0:37
  • \$\begingroup\$ Thanks for the help @TimWescott and CharlesCowie. That means that without the control board that I broke I it will be impossible to fix? \$\endgroup\$
    – Tono Nam
    Apr 20, 2020 at 0:43
  • \$\begingroup\$ @TonoNam An "ESC" from a Radio Control model supplier will drive that motor, once you have the wires connected correctly. If you just disconnected the BOARD you MAY be able to use it motor drive ESC functions. \$\endgroup\$
    – Russell McMahon
    Apr 20, 2020 at 1:00
  • \$\begingroup\$ @CharlesCowie Sensorless motor control is now quite common. The back EMF waveforms are used to deduce rotor position and velocity \$\endgroup\$
    – Russell McMahon
    Apr 20, 2020 at 1:01
  • \$\begingroup\$ @RussellMcMahon it depends on what you want to do with the motor -- if it needs good starting torque, then sensorless doesn't work well. That's why you see sensorless brushless motors in RC planes and quadcopters (because there's almost no starting torque), and sensored brushless motors in RC cars (because the starting torque can be higher than the running torque). \$\endgroup\$
    – TimWescott
    Apr 20, 2020 at 1:43

1 Answer 1


The motor is a 3-phase, brushless DC motor. It could also be controlled as a permanent-magnet DC motor. The original board likely had some means for detecting the rotor position. I believe the least complicated control schemes depend of detecting the rotor position. The board switches the winding in a sequence that is an approximation of an AC waveform, but the process is called "electronic commutation." It might be possible to design a new board to replace the one that has been damaged, but that would be a rather challenging project. However it would be even more challenging to design a controller to work without sensing rotor position.

If the housing is sufficiently intact to hold the bearings in proper alignment, the motor could be used as an AC generator. It would generate a three phase voltages . The windings would need to be connected together in either a wye or delta configuration.

Re Connections

If the added connection table means that there is a direct connection that you can see or zero ohms between 1-2, 3-4 & 5-6 and somewhat more than zero ohms but still a low resistance between 2-3,4-5 & 6-1 the windings have a delta connection.

  • \$\begingroup\$ Microcontroller manufacturers (like ST) have eval boards designed for driving brushless motors -- but if your skill level tops out at Arduinos, it would be a significant learning experience to make such a thing work. \$\endgroup\$
    – TimWescott
    Apr 20, 2020 at 1:44

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