28BYJ-48 stepper seems to have no torque

I made a machine for a school project, but the stepper motor keeps stopping and "jumping" around, twitching back and forth when confronted with any kind of load. I can stop it by lightly holding the shaft with two fingers. I'm powering it directly from an Arduino, which is also powering an HC-SR04 and a 9G servo. My original thought was that it was a power issue which could be easily resolved using a 1.5A voltage regulator but I'm not sure.

i have no idea which driver I'm using. Whichever one came with the ELEGOO Super Starter Kit.

To be clear the stepper works fine, but it has astonishingly low torque and stops when confronted with next to no load.

Get rid of the regulator! The current to the motor is set by the driver board and you need to find which one it is and how to set the current limits to match your motor.
Paul

Neither the servo nor the stepper can be powered from the Arduino.

No Arduino board is a power supply. The stepper and the servo should be powered by external supply capable of supplying the correct voltage and sufficient current. I would budget 1A @ 5V or 6V for the servo. I have no experience with that stepper, but 0.5A @ 5V should be a sufficient power supply for it.

Are you sure that the stepper is wire to the driver right?

edit: I am guessing that the stepper driver is a ULN2003 and is not adjustable. See here.

I haven't integrated it yet. I'm asking if I should.

Currently everything is being powered by the Arduino, and I'm wondering if I should use a 5V 1.5A regulator connected to 12V DC instead of just the Arduino.

The servo is fine with just the Arduino as a power supply.
Not sure about the stepper.
And yes, the driver is a ULN2003.

You say that now, but have you put the servo under load? I am not just repeating what I saw somewhere on the internet. My recommendation for an external supply for the servo and the stepper is based on experience.

You shouldn’t be wondering, do it.


You will reap the benefits of doing this. i.e. buying a new Arduino.

Yeah I have. But it's not actually being loaded for the current application. It just has to nudge a marble.

1: I'm at school, as are all of my Arduino supplies, and my 5V regulator is at home.
2: I just have to nudge a marble. Also the Arduino I'm using was $5 on Banggood. I got that particular one because it was disposable.

How is the Arduino going to be powered in the end application?

What Arduino board do you have?

I'm using a knockoff UNO from Banggood, and the power supply is a 12V wall jack.

So you are powering the Uno from 12V into the power plug or Vin?

Power jack

Let’s say your motor requires 100mA.

Let’s assume the Arduino needs 50mA.

12v on the jack means 12v(jack) - .7v(diode) = 11.3v to the regulator.

11.3v - 5v = 6.3v across the regulator.

6.3v * 150mA = 0.945watts dissipated in the regulator.

:thinking:

Disasterous way of powering....

Close to smoke. Get a fire distinguisher....

The Arduino's onboard regulator does get very hot if that's what you are wondering.

We are wondering if you are wondering why it gets hot?
Paul

We are wondering if you are wondering why it gets hot?
Paul
Larry