2
\$\begingroup\$

I have 16 dc vibration motors bought from Ali, rated at 0.1A, Vdc 3-9v.

In fact they consumed 0.15-0.18A from 9V. Starting resistance varied from 20 to 30 ohms.

I connected all 16 motors to PCA9685 16-channel pwm controller that runs at 1.6 kHz. I have 8 identical pcb boards as shown below, each pcb is connected to its pair of motors. The power source V1 is supplying all boards and is capable of 11A / 9V.

The diode and capacitor is near the motor. Each motor is connected by two copper multi-strand non-shielded wires, 1.6 mm sq diameter, 16 ft. length.

During testing I had been having blown fuses and motors with degraded resistance (almost short circuited). Not all of them, not in one time. I haven't observed any spikes on power source terminals.

Some motors heated more than the others. I've got two motors at 60°C but quickly disarmed them. Others were not more than 10°C above ambient temperature.

As a safety measure I programmed soft pwm transition, lowered maximum duty cycle, lowered the power source voltage to 8V. So far looks like it helped.

The actual questions are:

  1. What else can I do? I have a low budget so I cannot implement current sensing. Do you think linear voltage regulators could help to protect the motors?

  2. From your experience, can you say that the motors were doomed to burn in my setup or not?

schematic

simulate this circuit – Schematic created using CircuitLab

\$\endgroup\$
  • 2
    \$\begingroup\$ The part that says "3-9V" seems suspect to me. \$\endgroup\$ – Scott Seidman Sep 25 '17 at 10:21
  • \$\begingroup\$ That's exactly what they wrote. \$\endgroup\$ – Dmitry Pryadkin Sep 25 '17 at 10:33
  • \$\begingroup\$ Never seen a vibration motor rated for 9V before. \$\endgroup\$ – Brian Drummond Sep 25 '17 at 10:56
  • 2
    \$\begingroup\$ "bought from Ali, rated at ...". There's the problem. You seem to actually believe what it says. LoL! I've got a bridge across the Hudson I can let you have at a special low price. Hurry! Order now! \$\endgroup\$ – Olin Lathrop Sep 25 '17 at 11:05
  • 1
    \$\begingroup\$ Gah! Upside down drawing. WHY? \$\endgroup\$ – winny Sep 25 '17 at 11:36
0
\$\begingroup\$

Start at 0 and slowly increase the voltage on a motor you haven't yet burned up. Find the voltage at which it starts rotating. Then consider maybe 1.5x of that the limit.

It is very unlikely that one of those little vibrating motors can actually take 9 V indefinitely without frying.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.