Gigiux
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12 V step motor overheated with ULN2003 controller

Fri Aug 30, 2019 5:46 am

I connected a 28BYJ-48 step motor to a ULN2003 controller, then attached a power pack with 8 AA batteries to the ULN2003 using the pins dedicated to the 12 V input (red cable on the + pin). I checked beforehand that the pack was generating 12 V using a multimeter, and it was. I then run a program that worked with a 5 V motor, but nothing happened. Or better, the motor was very hot but unresponsive.
What did I get wrong?

pcmanbob
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Re: 12 V step motor overheated with ULN2003 controller

Fri Aug 30, 2019 7:59 am

Without being able to see your set up its hard to say, I suggest you post some pictures showing your wiring , making sure we can see it in detail.

You should also check that the 12v motor you are using has the same step sequence as the 5v motor your were using.
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Gigiux
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Re: 12 V step motor overheated with ULN2003 controller

Sun Sep 01, 2019 4:40 pm

Hello, this is the configuration:
20190901_181828.jpg
20190901_181828.jpg (172.93 KiB) Viewed 670 times
The red and black are the + and - plugs from the power pack. Then the red, yellow, white orange are plugged on 23, 24, 25, and 18.
I assumed the step sequence is the same since the motors looks essentially the same:
https://www.amazon.de/gp/product/B07W65 ... UTF8&psc=1
https://www.amazon.de/gp/product/B00DGN ... UTF8&psc=1
But I think the ULN2003 card is burnt: today nothing happened at all. By the way, what controller would you suggest for 12 V motors? One that can have at least 4 motors attached. Tx

pcmanbob
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Re: 12 V step motor overheated with ULN2003 controller

Sun Sep 01, 2019 6:24 pm

Well the first thing I can see is that you have no ground connection between the driver board and the pi, with out this there is no way it will work.
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Gigiux
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Re: 12 V step motor overheated with ULN2003 controller

Mon Sep 02, 2019 5:43 pm

why do I need a ground? isn't' the current passing from the + to the - pole, the latter being the ground? Anyway, how would I do that? Tx

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rpdom
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Re: 12 V step motor overheated with ULN2003 controller

Mon Sep 02, 2019 6:08 pm

Gigiux wrote:
Mon Sep 02, 2019 5:43 pm
why do I need a ground? isn't' the current passing from the + to the - pole, the latter being the ground? Anyway, how would I do that? Tx
The main current is passing from the +ve to what you call the -ve pole (more correctly known as 0v or ground), but what of the drive voltage from the Pi? Where does that go? With no 0v connection back from the driver board to the Pi it has nowhere to go and won't do anything.

Gigiux
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Re: 12 V step motor overheated with ULN2003 controller

Tue Sep 03, 2019 8:19 pm

SO if I understand correctly, the GPIO signal gets into the ULN2003 but then need a ground PIN to get out. This besides the main supply, that is. I thought that electricity was dissipated as heat by the motor. So why there was no such need with the 5 V connection? Because the GPIOs were going into the ground together with the input 5 V?
Anyway, how do I provide a ground since the ULN2003 does not have pins left (apart for the two for the 5 V input)? Tx

pcmanbob
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Re: 12 V step motor overheated with ULN2003 controller

Tue Sep 03, 2019 8:35 pm

Yes the 3.3V will need to go to ground but it needs to be the ground on the pi because that's were it came from, you need to connect a second wire to the ground pin on the ULN2003 board and connect this to one of the pi ground pins.

How you do this depends on what options you have at hand, if you have breadboard then connect the ground pin of the Uln2003 board to this then connect the pi ground and your motor supply to it there,

You could also solder 3 jumper wires together and the connect an end to each ground pin.
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Gigiux
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Re: 12 V step motor overheated with ULN2003 controller

Thu Sep 05, 2019 5:28 am

thank you, looks like a lot of work. Is there a tutorial with images/video i could look at?

pcmanbob
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Re: 12 V step motor overheated with ULN2003 controller

Thu Sep 05, 2019 10:20 am

A lot of work !

It took me longer to write this post than to set up the example

Image

Image

So the pi represents your pi and its ground , the motor driver board represents your ULN2003 board and its ground and the battery represents your motor power supply and its ground, all connected together on the breadboard . you could just as easily solder the 3 wire together at the common point if you don't have a bread board.

so what's so hard and a lot of work ?
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Gigiux
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Re: 12 V step motor overheated with ULN2003 controller

Fri Sep 06, 2019 6:01 am

Well, I did not mean 'lot of work' as in the Sistine Chapel, but still it needs a clear plan. If I understand you, I plug the positive cable from the 12 V battery normally into the ULN2003, but for the negative I need to solder three cables together (for I won't be using the bread board for the real thing), with one end plugged into the ULN2003's negative pin, one end into the negative plug of the battery and one end into a GRND pin of raspberry. And the board is going to withstand the 12 V of the return current? Thanks you

pcmanbob
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Re: 12 V step motor overheated with ULN2003 controller

Fri Sep 06, 2019 10:23 am

The 12V current from the battery will no be flowing back or trough the pi , current flows round a circuit, so current from the battery will want to go back to the battery and current from the pi will want to go back to the pi.

like this

Image
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blimpyway
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Re: 12 V step motor overheated with ULN2003 controller

Fri Sep 06, 2019 8:04 pm

Gigiux wrote:
Tue Sep 03, 2019 8:19 pm
SO if I
....
Anyway, how do I provide a ground since the ULN2003 does not have pins left (apart for the two for the 5 V input)? Tx
See documentation, page 4 https://www.st.com/resource/en/datasheet/uln2001.pdf
Pin 8 is ground pin. It has to be connected to both Pi's GND and to the 0V (ground) of the 12V supply.

PS and wire uln's pin 9 (common free wheeling diodes) to +12V that will provide an escape for inductive back-emf spikes from switching on/off the coils. Without it the ULN might get fried.

pcmanbob
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Re: 12 V step motor overheated with ULN2003 controller

Fri Sep 06, 2019 8:46 pm

blimpyway wrote:
Fri Sep 06, 2019 8:04 pm


See documentation, page 4 https://www.st.com/resource/en/datasheet/uln2001.pdf
Pin 8 is ground pin. It has to be connected to both Pi's GND and to the 0V (ground) of the 12V supply.

PS and wire uln's pin 9 (common free wheeling diodes) to +12V that will provide an escape for inductive back-emf spikes from switching on/off the coils. Without it the ULN might get fried.
The OP is using a ready made stepper motor driver board based on the ULN2003 so it is reasonable to assume that pin 9 will already be connected to the motor supply + pin on the board.
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blimpyway
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Re: 12 V step motor overheated with ULN2003 controller

Sat Sep 07, 2019 9:39 pm

ook sorry for that. Just seen the discussion on GND connections

Another thing is quite unclear:
I then run a program that worked with a 5 V motor, but nothing happened. Or better, the motor was very hot but unresponsive.
What did I get wrong?
What motor was that?
Was it powered through the same ULN board (same type of stepper) or a different kind of motor with a different driver board?

Gigiux
Posts: 30
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Re: 12 V step motor overheated with ULN2003 controller

Tue Sep 10, 2019 7:38 pm

It was exactly the same version of the motor but at 5 V, a 28BYJ-48 with ULN included https://www.amazon.de/gp/product/B00DGN ... UTF8&psc=1. I simply changed to a 12 V to have more torque https://www.amazon.de/gp/product/B07W65 ... UTF8&psc=1.

Before burning anything, this is the connections that I prepared:
This is the triple connection, the arrow shows TOWARDS THE BATTERY
20190910_211449.jpg
20190910_211449.jpg (184.47 KiB) Viewed 304 times
this is the connection on the ULN2003 board (and I mean controller not the transistor
20190910_211515.jpg
20190910_211515.jpg (99.25 KiB) Viewed 304 times
and this is the third part of the connection, fixed on physical PIN 6.
If everything checks, then I'll try out. By the way, how would I know if the 12 V motor is still good? The ULN2003 is still functional since it moves the 5 V version; what if the 12 V does not move? is there a way to check if it is still functional?
Thank you

Gigiux
Posts: 30
Joined: Wed Apr 10, 2019 7:28 pm

Re: 12 V step motor overheated with ULN2003 controller

Tue Sep 10, 2019 7:39 pm

It was exactly the same version of the motor but at 5 V, a 28BYJ-48 with ULN included https://www.amazon.de/gp/product/B00DGN ... UTF8&psc=1. I simply changed to a 12 V to have more torque https://www.amazon.de/gp/product/B07W65 ... UTF8&psc=1.

Before burning something, this is the connections that I prepared:
This is the triple connection, the arrow shows TOWARDS THE BATTERY
20190910_211449.jpg
this is the connection on the ULN2003 board (and I mean controller not the transistor
20190910_211515.jpg
and this is the third part of the connection, fixed on physical PIN 6.
If everything checks, then I'll try out. By the way, how would I know if the 12 V motor is still good? The ULN2003 is still functional since it moves the 5 V version; what if the 12 V does not move? is there a way to check if it is still functional?
Thank you

pcmanbob
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Re: 12 V step motor overheated with ULN2003 controller

Wed Sep 11, 2019 9:58 am

Just showing us part of the wiring is not really very helpful, from what I can see things look to be connected in the right places but there is a lot I can't see.

Why not take a picture showing all of the wiring to the pi, driver board, battery and motor , then if its to big to post here upload it to imgur.com and post a link to it here.
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Gigiux
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Re: 12 V step motor overheated with ULN2003 controller

Wed Sep 11, 2019 5:41 pm

It worked! I guess the schematic doe not matter now, anyway it was the same as shown in the previous picts. Thank you for support

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