Inqling - A Test Mule

First Question - Drive Units.

Does anyone have any experience with these:

28BYJ-48 ULN2003 5V Stepper Motor + ULN2003 Driver

The Internet is says the top speed is between 10 and 15 rpm.  I've squeezed 18 rpm out of them. 

• Has anyone use these as direct drive units to the wheels?
• Was there enough torque to actually move?

Thanks.

VBR,

Inq

@inq If you don't mind me lurking in the background?  The idea intregs me:  Specificially the "simple" maybe brainDead device that can be nurtured and grown into a "whatever" based on personal taste.

I am not sure I will ever build one - I might? I am subscribed.  Maybe I can take what I learn and make an amphibious drone (not necessarily flying; under water though not like a submarine either:  say, a crawling/rolling thing to play in a swimmingPool, bathTub or kiddiePool)?  Now I am meandering along the, "What if" that extends outside where you said you were taking this.

Parts list is good. I would never know what to buy.  I'll wait a bit for it to finalize and learn if it fits here?

Posted by: @darup

@inq If you don't mind me lurking in the background?  The idea intregs me:  Specificially the "simple" maybe brainDead device that can be nurtured and grown into a "whatever" based on personal taste.

I figure it being three parts:

1. The hardware in that picture above covers it.
2. The design and 3D printing of the chassis will be rather involved, but I'll supply the STL files if anyone is interested.
3. The software for just the RC portions, will be trivial and I'll supply that as well.

I just had a Dah! moment... I've been writing in your thread without knowing what the purpose of the thread was.  Dah... I assume there are some good sources recommendations for getting some 18650 cells???  I don't need them for myself.  I have plenty of "laptop" cells.  🤣  But, I'd buy new ones for students.

@darup

Posted by: @darup

If you don't mind me lurking in the background? 

Lurk ahead!

For every post here, there are ~30-50 lurkers 😉

I was just getting started CADing up a chassis to mount all the parts and strategizing how to lay them out. 

I loathe wires... behind my computer, behind my stereo, behind my TV... in my projects.  I also would rather avoid having to solder the pieces together because this is just a test mule.  It will come apart.  

I was deciding on whether to use a WeMos or a NodeMCU.  The NodeMCU has more pins for future additions, vision, touch, sensors... but I found something that addresses the wires issue a little and that takes precedence.  

The NodeMCU has all the D* pins on one side.  The WeMos has D1-D4 on one side and D5-D8 on the opposite side.  😆 

BOOM...Flip them over and plug them in... Voilà!  (No... not a great revelation, but 8 wires gone... priceless!)

Just have to change the constructor on one of the steppers...

Stepper sLeft = Stepper(stepsPerRevolution, D4, D2, D3, D1);
Stepper sRght = Stepper(stepsPerRevolution, D5, D7, D6, D8);

Now!  I just have to get over that they're not symmetric.  🤨 

Alpha Body

Alpha Parts

Posted by: @inq

Alpha Body

Interesting design. Why does it look like it's been out too long in the sun ?

Posted by: @inq

Dah... I assume there are some good sources recommendations for getting some 18650 cells??? 

https://www.sparkfun.com/products/12895

Digikey resells these and I have purchased a bunch of them.  I had one that wouldn't take a charge and Digikey send me out a new one, no questions asked!

Have you noticed how the price of everything is going up lately?  I'm sure that I didn't spend $6.50 USD for these six months ago.

Tom

@thrandell 2 years ago I got 10 NCR18650B 3400mAh from AliExpress for $39.99 including shipping. Here is a link to the Panasonic 18650 3400mAh. These are the good ones. in units of 10 I will pay $56.48 CDN, not too bad. I just ordered them!

Posted by: @thrandell

Have you noticed how the price of everything is going up lately?  I'm sure that I didn't spend $6.50 USD for these six months ago.

I'm glad you said this.  I've always discounted SparkFun and DigiKey... they've always been at least 2x Amazon, eBay... etc.  Although I haven't done a thorough search yet, a quick 10,000 foot view number seemed nearer $8 on Amazon.  Seems they're out though.  Like I mentioned in another thread... I tear apart laptop bricks and usually get about 75% good 18650 batteries.  Those are fine for my purposes, but I'll buy new for students.

Posted by: @thrandell

Have you noticed how the price of everything is going up lately?

Oh hell yeah!  I need to build a shed...  a sheet of OSB that used to be under $10 two years ago, is now over $50.  I might have retired too early!

Posted by: @will

Posted by: @inq

Alpha Body

Interesting design. Why does it look like it's been out too long in the sun ?

Is this any better?   

Posted by: @inq

Is this any better?   

Yep, that explains it 🙂

I thought it might be so that the heavier base would keep the centre of gravity lower to improve the turning moment while driving the wheels.

But instead, the eyes have it 🙂