Electronics > Beginners

Need advice on designing a stepper motor application that can be commercialized

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engineheat:
Hi,

I have a stepper/servo motor application that I want to commercialize, and here are the requirements:

1. The stepper motor will be rotating back and forth like a pendalum (180 degree total travel), with a period of roughly 2-3 sec.
2. The torque shall be powerful enough to drive a cassette player.
3. I really prefer not to use Li-ion as it has a dangerous reputation and I want to commercialize something with less risk.
4. I hope the battery can be recharged via a USB cable, rather than using alkaline batteries.
5. Operation should be quiet.

So far, I only found the 28 BYJ48 motor to have the size, cost, availability, torque, and quietness attribute that I need. However, it requires voltage of at least 4V. The drive circuit is simple. Lots of off the shelf drivers uses ULN2003, but I found a more efficient way using MOSFET.

The simplest way would be to use 4 AA batteries to power it. But I hate to have to swap batteries all the time. How do I design the device so that it can be charged via USB like a cell phone?

Maybe I can use a single AA battery, but that'll require a boost circuit which is hard to design. Moreover, the charging circuit is kinda out of my league now too.

Should I just go with the simple approach (4 AA Nimh pack) and commercialize it first? (have a minimal working product), or try to go fancy and go with USB charging? Unless there are off the shelf circuits that'll do the charging and boost the voltage, it'll be too much of a risk from a time and design stand point. Last thing I want is have the device start a fire.

I researched boost circuit, and the best I can do is to buy an IC chip and I still have to design around it. While I'm always up for a challenge, I don't feel it's the best approach from a business stand point.

What is your suggestion?

Thanks

Nitrousoxide:
To get the energy density required and to satisfy the recharging requirement, you will have to use Li-Po/Li-ion batteries.

If you want simplicity, you can get whole boost modules that even include the inductor (they are usually more expensive). However, you can just go for a boost converter (integrated MOSFET). Most boost converters will have a recommended or example layout in the datasheet, copy that and it will be fine. I personally did that for my first PCB and ran into no issues at all.

Some controllers can even user micro stepping to reduce the stepper noise

Mechatrommer:

--- Quote from: engineheat on July 10, 2018, 03:07:20 am ---Maybe I can use a single AA battery, but that'll require a boost circuit which is hard to design. Moreover, the charging circuit is kinda out of my league now too.
--- End quote ---
you want to commercialize a thing and you are not up to the task yet? ironic. maybe you can start learning and experimenting step by step. first charging circuit, and then boost circuit etc etc...


--- Quote from: engineheat on July 10, 2018, 03:07:20 am ---How do I design the device so that it can be charged via USB like a cell phone?

--- End quote ---
your best guru will be the existing commercialized products, licensed, tested and verified by real engineers and standard organizations. what battery cell phones use? right, lion or lipo (worst safety). do you see most products around use NiMH or SLA (safer)? no (or very seldomly seen), why? since your research contradicts with what happening around you, there must be something flawed in your finding (or methodology or mentally) imho. just because of few isolated incidents and you are not going to use it is like banning petrol or hydrogen car from the road because of some explosions petrol or hydrogen related.


--- Quote from: engineheat on July 10, 2018, 03:07:20 am ---I researched boost circuit, and the best I can do is to buy an IC chip and I still have to design around it. While I'm always up for a challenge, I don't feel it's the best approach from a business stand point.

--- End quote ---
can you point out which product (consumers grade) design their own boost circuit from raw transistors?

there are many possibilities in the advice, use lion/lipo/lifepo4 (because it norm today), or use NiMH or SLA (i'm sure you dont want that) and then googling for the charge circuit and read books on how each type of battery should be properly charged. i know this is beginner section but instead of suggesting on one particular and narrow (minded) possibility, i prefer provoking your mind so hopefully it will directed in the right way as many proven commercial companies do. hope it helps.

james_s:
Li-Ion is the way everything has gone, if you build a commercial product with NiCd or NiMH it's going to look archaic. There's no reason to be afraid of Li-ion as long as the charging circuitry is designed sensibly, the high current LiPo packs used in RC models and such can be dangerous but Li-ion are used in literally billions of mobile devices and laptops with very few incidents. NiCd, NiMH and lead acid batteries can also start fires, though usually in the wiring. Any time you have stored energy you can have a fire.

stian:

--- Quote from: engineheat on July 10, 2018, 03:07:20 am ---Hi,

I have a stepper/servo motor application that I want to commercialize, and here are the requirements:

1. The stepper motor will be rotating back and forth like a pendalum (180 degree total travel), with a period of roughly 2-3 sec.
What is your suggestion?
Thanks

--- End quote ---

Hi.

My 1st question back to you is. who in their right mind do you think would buy a software that does this?
My answer is no one i think. and there is no point in that.

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.
im using a arduino uno "Atmega328" with code i written in C "not C++" to control the 4 stepper motors over Usb/serial.

cant really say i would reccoment the 28 BYJ48 motor and the ULN2003 driver
my project involving them. https://i.gyazo.com/814da14d11abdafc40e51d200ef6c370.jpg

You should maybe look for a opensource application that already exists that uses Gcode or something and fork and customize it.
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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