Electronics > Beginners
Need advice on designing a stepper motor application that can be commercialized
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engineheat:

--- Quote from: Nusa on July 12, 2018, 06:21:57 pm ---Why reinvent the wheel? There are probably thousands of different USB battery bank packs out there, which are charged via USB and provide power via USB. If you design your project to run directly from USB, then the power aspect is just a matter of buying one with sufficient capacity for your requirements.


--- End quote ---

I really like this idea, thanks!
engineheat:

--- Quote from: stian on July 12, 2018, 11:58:31 am ---
And more so. the 28 BYJ48 motor is rather a toy stepper, and with the ULN2003 they are rather slow if you ask me.
Also the ULN2003 driver + the 28 BYJ48 stepper does not work on 4v. you need 10V+ (12v preferable) on the steppers for them to have any torque.
I myself is using these 28 BYJ48 motor and the ULN2003 driver. "i bough them on ebay cheap :p" in controlling a usb microscope im 3d printing out.
i
also is your application only going to support one type of stepper? there are many types of stepper motors you know. Unipolar, Bipolar, 4-Wire Motor, 5-Wire Motor.. and so on.

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I plan to use the TI DRV777 to drive the 28 BYJ48. Please tell me what you think:
http://www.ti.com/lit/ds/symlink/drv777.pdf

They seem a lot more efficient than the ULN2003.

My application has really no requirement on the stepper. It doesn't even need to be a stepper. It's just that the 28 byj48 motor is the only one I've seen that's cheap enough, the right size, the right torque, and mostly importantly, quiet.  Most hobby servos makes a audible whine when they move. I also bought some really tiny 10mm or 16mm stepper motors and those don't seem to have enough torque, and didn't come in any common size. The 28 byj48 on the other hand is widely available and cheap.

If you know of any other options, pls let me know. My application is slow speed, and quietness is important. I wonder what kind of motor is used for cassette players because they seem to have the right speed, noise level, and torque for my application.

Thanks
engineheat:

--- Quote from: Doctorandus_P on July 13, 2018, 12:38:03 am ---What kind of quantity do you expect to sell of this product?

It seems strange to me you want to build a commercial product, but apparently do not have the skills to design it. Maybe you should find a partner for the design.

The USB power banks (should) have built in protection for a Li-Po battery. Because of the vast numbers of these things built, special chips are made which combine over and under voltage protection and step-up to 5V in a single IC.

Be carefull with the 28Cxxxx stepper motors. These are built by multiple different manufacturers and with different gear ratio's (1:16 and 1:64 are both common) and voltages. (6V and 12V is common).
I've bought some of these with the same voltage rating, and they had a pretty big deviation in DC coil resistance.
Look closely at pictures of a bunch of these on Ali / Ebay / Etc. You will see small differences between them.

With battery operation, power consumption is always a big issue. Stepper motors are bad at this. They consume the most energy when doing nothing, if you constantly apply voltage to the coils. You could also increase efficiency by opening them and wiring them as bipolar motors and use a proper dirver chip for them.

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Quantity? 10000 to 20000 hopefully

This project is slightly beyond my skill at the moment, but if I use the power bank idea like you mentioned, then I think the rest is doable. I really like the power bank idea. I don't even need to worry about the charging or the boost converter. I can just design my device to interface with any USB power bank and the customer can purchase the power bank on their own. Some of those small tubular USB battery bank actually looks pretty nice with my design.

As for the stepper motor being inefficient, so far I have not found a better solution in terms of quietness, torque, size, cost/availability than the 28 byj48. My post above this provides more detail.

Thanks
IanB:
If possible I buy products that use 4 AA cells (or maybe 4 AAA cells) so that I can stick 4 Eneloops in there. Advantage: I have a stock of Eneloops I can swap between products, I can simply replace them with fresh ones when they run down, and if necessary I can stick alkaline cells in there. I can buy alkaline cells at 4/$1 at Dollar Tree, which is cheap enough to be disposable.

I try to avoid products that use Li-Ion unless it is a replaceable battery of a standard size, since the life of the battery will be the life of the product. Given that the product will last forever and the battery will not, Li-ion is a bad idea.

But I am not your typical consumer...

(Your typical consumer will buy the product, get bored of it within a year, and dispose of it.)
Nusa:

--- Quote from: engineheat on July 15, 2018, 01:29:50 am --- I wonder what kind of motor is used for cassette players because they seem to have the right speed, noise level, and torque for my application.

--- End quote ---

Google "cassette player motor" if you really want to know.

It's difficult to recommend anything without knowing the precision requirements of your project.
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