Timelapse Circuit HELP!


#1

Hi my son has designed a time lapse motion track bed we are having real problems with the circuit board and wiring we have had several attempts and at one point had it all working but then it seems to have blown something. its getting expensive now and I was wondering if anyone could help wire this up for us happy to pay and ship anywhere in uk.

We are using the following 4 wire stepper motor, Arduino board, Reprap stepstick A4988 motor driver control board.

If anyone can help it would be appreciated my son has put a lot of time and effort into this but we seem to be stumped by the circuitry or control to stop the boards from blowing.

Thanks

Neill


#2

Hi @neillmartin1,

Can you start by posting a wiring diagram? I’ll see if I can get someone from the community to reach out and help!

-B


#3

This seems to suggest that if you have any potential between your logic power and stepper motor grounds, magic smoke may come out.

Make sure you are drawing power from the same mains source and that all grounds are terminated at a single location to minimize ground loops in high current applications. While you are at it, check the spec on your stepper motor and ensure your hardware has the current specs to drive it.

Also, make sure that the stepper driver current limiting pot is turned down low and then slowly raise it up until your steppers move.

Cheers,

Craig


#4

Hi thanks for this I think as per the other post suggests current overload to the board might be the issue but we just don’t have the in depth knowledge of electronics my son is an aerospace engineer so is good with jet engine parts!


#5

First thing I would do is run a wire from your motor power supply ground to your logic power supply ground.

Are the logic power supply and motor supply fed from the same wall socket?

Also, what model of stepper motor do you have?

Craig


#6

Hi Craig

The power comes from 12v motorcycle batterys

Regards

Neill


#7

So you have a single source power supply for the logic and the motors?


#8

Hi Yes single source of power to the logic board as per the pics. Also here is the stepper mtr type.


#9

So this is a 24-48V 2.8A motor. The A4988 is capable of up to 35V but no more than 2A.

You need something like a Nema 17 stepper if you are using 12V. The channel draw would be 1.68A, so safe for use with the A4988.

So to be clear, you are using a 12V battery to drive the stepper, and off that same 12V battery, you have a linear regulator supplying the logic?

Cheers,

Craig


#10

Hi Craig

thanks for your help. Yes we are using the 12v battery to power the board and stepper driver. Not sure what you mean regarding a linear regulator supplying the logic? The power to the Ardunio comes directly from the battery. The A4988 is then powered from the board.

Thanks

Neill


#11

I was looking at your schematic and not your wiring diagram. The schematic shows a 3.3-5V supply. You are just using voltage from the Arduino which is powered from your PC to supply the logic on the stepper driver.

Yeah, get a lower current stepper or get a higher current driver and a second battery in series if you want this to work. Sounds like you don’t have any real torque requirement, so a lower current stepper is better.

Cheers,

Craig


#12

Hi Craig
Thanks the Ardunio is not powered from the P.C it is powered by the 12v battery is this ok.

Thanks

Neill


#13

It’s fine. The Uno has a 5V linear regulator on board.

So you understand that you need to get a Nema 17 stepper or grab one out of an old hard drive or something. The channel current must be below 2A.

Craig


#14

Hi yes thanks Craig yes I will order one and new boards and fingers crossed!


#15

Hi Craig

My son is worried as the Nema 17 stepper has half the torque to the one we used do you think this will do the job to move the bed with the camera attached/

Thanks

Neill


#16

How much does it weigh?


#17

Approx 2/3 kilo


#18

Hi Can anyone advise if the Nema 17 stepper will be man enough to cope with the camera on the moving bed ?

Thanks

Neill


#19

Hi can anyone advise on the last comment re the Nema 17 Stepper?


#20

Neill,

The short answer is, it depends on your mechanism. I could lift a car with the right pully setup.

If it’s a belt drive, your sled is on a ball bearing rail, and there is no incline, then I don’t think you need much force to overcome friction.

If you have a fishing scale, I would remove the belt, load up the sled and see what it takes to get it moving, then convert back to Newtons to see what torque you need.

Note, all Nema 17 motors are not created equal, so make sure you check the torque specs of the specific model. Make sure it is less than 2A. I suggest the 1.68A ones so you have some room.

Note that a typical Nema 17 has a holding torque of 33N-cm, this roughly equates to the ability to lift 3 kg, so pushing it will be significantly less.

Craig