# Which diode for vibration motor ?

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.

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. 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?

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?

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..

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.

Measure the motor's winding resistance...

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

4,5 ohm

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.