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I bought 5 identical 12V drill DC motors. First thing I did was to measure (for one of them):

  • the current consumption without any load: 0.16A
  • the inrush current at turning the motor on: 1.5A
  • the stall current: 1.5A (the lab power supply showed 2A once)

I plan to use 5 of these motors to make a tool for drilling 5 equally spaced holes in a 3mm thick wood. I have a DC power supply (12V, 10A) which I intend to connect them to. The diameter of the drill collet, which will be used is 2.5mm. The pieces of the wood, which I'll be drilling holes into, are part of a honeycomb frame (2 pieces per frame, 5 holes per piece).

My question are:

  • can I connect them directly to the power supply and activate them using a bistable switch (while using flyback diodes)?
  • or should I use an arduino, 5 MOSFETS, flyback diodes (I have a lot of 1N4007) to slowly (with PWM) start each one?
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  • \$\begingroup\$ All the tutorials, which I've seen, about controlling DC motors with arduino through a transistor, showed a rectifying diode, to protect the transistor. I figured they are also necessary here? \$\endgroup\$ – RunoTheDog Jun 10 '17 at 12:13
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    \$\begingroup\$ Change 'rectifying' to 'flyback' and your question will make more sense. \$\endgroup\$ – replete Jun 10 '17 at 12:34
  • \$\begingroup\$ Just indulge me - how many sets of holes will you be drilling and what's the major overall dimension across the holes? \$\endgroup\$ – Paul Uszak Jun 10 '17 at 12:36
  • \$\begingroup\$ Is 14N007 actually 1N4007? \$\endgroup\$ – Spehro Pefhany Jun 10 '17 at 13:25
  • \$\begingroup\$ @Spehro Pefhany: Correct. Sorry for the typo. \$\endgroup\$ – RunoTheDog Jun 10 '17 at 13:35
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Q1: Can I connect them directly to the power supply and activate them using a bistable switch (while using flyback diodes)?

Yes. You can switch them with one big switch or five smaller switches (mechanical or transistor). Effectively you are connecting them all to the supply.

Q2: Or should I use an arduino, 5 MOSFETS, flyback diodes (I have a lot of 14N007) to slowly (with PWM) start each one?

You are unlikely to be starting them on load but your test measurements indicate that you may still reach supply capacity when all are started simultaneously. This may or may not be a problem. I wouldn't recommend the complexity of PWM control unless you think you might need speed control in the future. A simpler alternative would be to sequence the motor starts 1 - 2 - 3 - 4 - 5 with, say, 0.25s between them.

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