Which diode for vibration motor ?

Using Arduino Motors, Mechanics, Power and CNC
#1

I want to control this eight vibration motor with arduino:

which diode should I use? I always don't know which diodes for which motor.

And which transistor or MOSFET for this motor? Can I try with TIP122 and 2.2k resistor first?

they need 3v, they are also strong enough with 2v and they take up to 1A current.

#2

Which Arduino? What is the motor's power supply voltage? A 1N4002 diode should work though it might be half the size of the motor. :slight_smile: A TIP120 is going to drop 1.5 to 2V, is your power supply at least 4.5V? A 1k to 2.2k resistor should be OK. Did you say 8 motors? Can your PS supply enough current?

#3

I am using Arduino UNO and Mega 2560.

Motor voltage is 3V and the current was around 800mA if I connect motor directly to power supply. With TIP122 the current is lower like 350mA. I dont know why. The duty cycle was 100% and the Arduino pin out was 5V to Base of TIP122 with 2.2k ohm.

Yes, I want to control 8 motors. I have only TIP122 in my home.

Will this work ?

Yes, power supply got enough current

Should I better order TIP120 or other MOSFET?

#4

Did you measure that motor current?
I highly doubt that a 7x25mm motor draws that much.
The web page says it uses 20mA. (0.06watt/3volt=0.02A)
If so, then an ULN2803 might do.
Leo..

#5

Yes I see that current on my laboratory power supply. So I am wondering that too. I thought it should be 0.02A, but I see 350mA to 800mA. I wish, I could use ULN2803 but that current is too high. I will try use a resistor, but I fear the vibration will be very weak then.

edit: I guess this description on aliexpress is wrong. On other sale page, same motors in description it tells 300mA.

#6

Measure the motor's winding resistance...

#7

MarkT:
Measure the motor's winding resistance...

4,5 ohm

#8

So now you know the stall current for any supply voltage, I = V/R

When choosing a free-wheel diode for an inductive load, the diode needs to handle the full
supply voltage plus a safety margin (no problem for low voltage), and handle pulses of the
max (stall) current. So the pulse current rating is appropriate.

Otherwise the choice of diode is usually non-critical. If using PWM at higher speeds a fast diode
may be needed.

#9