$3 Stepper Motor & Board

erco · 2012-07-07 15:00

Edit: Price dropped a buck from $4 to $3 in under a month, so I changed the thread's title. See post #21.

Another decent score from Ebay China. I won the auction for $4 (1 cent bid plus $3.99 shipping) at http://www.ebay.com/itm/180912529491?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

or you can "Buy It Now" from the same seller all day long for $5, free ship: http://www.ebay.com/itm/DC12V-4-phase-5-wire-Stepper-Motor-ULN2003-Stepper-Motor-Driver-Board-/180909399906?pt=LH_DefaultDomain_0&hash=item2a1f0a5f62

For comparison, another seller's price is $9.50 shipped:
http://www.ebay.com/itm/DC-12V-Gear-Stepper-Motor-28BYJ-48-12V-4-Phase-Reduction-Step-Motor-/251096435139?pt=LH_DefaultDomain_0&hash=item3a768389c3

I make about 2000 steps per output shaft revolution. The seller claims 64 steps per motor revolution and also 1:64 gear reduction, so something doesn't add up. Good torque, not terribly fast. Good holding torque when off. A tad more backlash than I'd like, but certainly worth experimenting for $4! I'll get another and build a diffdrive bot. Video & simple code follow.

' {$STAMP BS2}
' {$PBASIC 2.5}
'spins stepper motor about 180 degrees & back
'uses P0-P3 to ULN2003 controller board
'press BoE reset to cycle

DIRL=%00001111
B0=1
FOR W1=1 TO 250
OUTL=3
PAUSE B0
OUTL=6
PAUSE B0
OUTL=12
PAUSE B0
OUTL=9
PAUSE B0
NEXT
PAUSE 100
FOR W1=1 TO 250
OUTL=9
PAUSE B0
OUTL=12
PAUSE B0
OUTL=6
PAUSE B0
OUTL=3
PAUSE B0
NEXT
OUTL=0
END

NWCCTV · 2012-07-07 18:18

WOW. That is a good deal. The driver alone is worth it and that is all I need as I have hundreds of stepper motors. I bid on one for .99. If I win it will come to $3.98 with shipping. Beat ya by a penny!!!!!

What are the In0 to In5 pins for? Also, does the motor power just get grounded to the stepper driver ground?

erco · 2012-07-07 19:28

NWCCTV wrote: »

Beat ya by a penny!!!!!

Hope so! Here's a better Buy It Now for $4.45 just in case: http://www.ebay.com/itm/Stepper-Motor-Driver-Board-ULN2003-Arduino-5V-4-phase-5-line-/180910023533?_trksid=p4012.m1374&_trkparms=algo%3DPI.WATCH%26its%3DC%252BS%26itu%3DUCC%26otn%3D8%26ps%3D63%26clkid%3D452068271057189954

It uses 4 uC connections, marked P1.0-P1.3, which I connected to Stamp pins 0-3. There are 3 empty holes on the PCB and thus 3 unused transistors in the ULN2003. The only other connections are to battery +12V and battery & Stamp common ground.

It's not unlike Parallax' own recommended stepper setup, so have a peek at their pdf: http://www.parallax.com/Portals/0/Downloads/docs/prod/motors/Stepper_Motor_27964.pdf

If you have motors and just need a board, here's one for $2.55: http://www.ebay.com/itm/ULN2003-Stepper-Motor-Driver-Board-for-Arduino-AVR-AR-M-/130720634151?pt=LH_DefaultDomain_0&hash=item1e6f8e9527

erco · 2012-07-07 19:33

DOH! $3.50! I AM UNDONE!

http://www.ebay.com/itm/5V-4-phase-Stepper-Motor-Driver-Board-ULN2003-for-Arduino-/251094989608?pt=LH_DefaultDomain_0&hash=item3a766d7b28

Prophead100 · 2012-07-07 19:45

I got a few of these for prototyping and was able to get fairly tight resolution of 4096 steps (512 times through 8-steps) per revolution with the gearing. Not too strong or fast for the final project but nice resolution and price for experimenting. Here's the Propeller test code:StepperMotorTest.spin

mindrobots · 2012-07-07 19:48

Two for $7? I couldn't resist that! Do the twins have a paypal account I can send to??

erco · 2012-07-07 20:20

My goal is to have everyone in the forum stepping in perfect unison!

erco · 2012-07-07 20:25

It's ridiculous. Now I'm down to $3.38 for a 5V version: http://www.ebay.com/itm/Stepper-Motor-28BYJ-48-With-Drive-Test-Module-Board-ULN2003-5-Line-4-Phase-5V-/300733004367?pt=LH_DefaultDomain_0&hash=item4605157a4f

Naturally I need 5V AND 12 versions, just in case.

John Abshier · 2012-07-08 10:12

Erco, you are too expensive. I wouldn't find these bargins and spend the money on my own.

John Abshier

erco · 2012-07-08 10:14

I'm still a cheap date in the long run, even when you add my dollar to the cost of ownership.

NWCCTV · 2012-07-18 16:46

I don't suppose you could draw up a quick schematic of how you have this connected, could you????? I just received my 12V motor and driver board and I want to make sure I do not fry anything. I understand the pinning to the Stamp but am a bit confused on the friver board. Do I just connect 12V to the pin next to the red jumper and then ground to the BoeBot Ground? In the Diagram on their site it shows to connect power supply where the red jumper is so I am a bit confused.

erco · 2012-07-18 17:25

Just like http://www.parallax.com/Portals/0/Downloads/docs/prod/motors/Stepper_Motor_27964.pdf

If you need more help I can reassemble and take a pic.

NWCCTV · 2012-07-18 18:16

Would you? I would appreciate it. I just do not want to fry anything. Thanks erco.

erco · 2012-07-18 21:22

Pretty simple. 2 wires from your motor battery (12V for you, 5V for me) to the two free terminals next to the jumper, marked GND and (surprise) 5-12V. Leave that jumper in place, which connects the flyback diodes. Also connect your battery motor negative ground to Stamp negative ground, Vss. Finally, 4 stepper board connections P1.0-P1.3 go to your Stamp pins P0-P3. Pop in this code and fire it up! Code runs motor ~180 degrees and back, press reset to cycle.

Don't be fooled by the wire colors in my photo, I used whatever servo connectors I had laying around, which work fine but didn't cooperate color-wise. Most glaring color error is on the battery connection, red=negative, black=positive, white=no connection.

' {$STAMP BS2e}
' {$PBASIC 2.5}
'spins stepper motor about 180 degrees & back
'uses P0-P3 to ULN2003 controller board
'press BoE reset to cycle

DIRL=%00001111
B0=2
FOR W1=1 TO 250
OUTL=3
PAUSE B0
OUTL=6
PAUSE B0
OUTL=12
PAUSE B0
OUTL=9
PAUSE B0
NEXT
PAUSE 100
FOR W1=1 TO 250
OUTL=9
PAUSE B0
OUTL=12
PAUSE B0
OUTL=6
PAUSE B0
OUTL=3
PAUSE B0
NEXT
OUTL=0
END

NWCCTV · 2012-07-18 21:52

Got it. Thank you. My concern was the red jumper and viewing the pic on EBay showed power to that. All is good. Thanks again.

erco · 2012-07-21 21:40

Down to just $3.31 now. Price wars! http://www.ebay.com/itm/Stepper-Motor-28BYJ-48-With-Drive-Test-Module-Board-ULN2003-5-Line-4-Phase-5V-/300733004367?pt=LH_DefaultDomain_0&hash=item4605157a4f

Hmmm. Three Hostess pies or a stepper & board? davejames?

mindrobots · 2012-07-21 21:43

HOSTESS PIES -> instant gratification
Stepper motor -> 10-15 day gratification

PIES PLEASE!!!

erco · 2012-07-22 00:39

Are you planning to have your 4-H club plant & grow Hostess pies? 'Cuz those take at LEAST 10-15 days to grow to maturity. Ordering shlepper motors might teach them patience NOW.

mindrobots · 2012-07-22 04:05

Hah! City folk! You can't grow Hostess Pies!! You need to start reading the book "Mule Eggs" to the twins in a couple years.

The phrase "teach them patience NOW" is funny. I can see a parent screaming something about "learning patience NOW" to their kid!

rjo__ · 2012-07-28 07:06

Erco... you are the best!!!

I ordered a boat load of these, both 5V and 12V. As you said..."something doesn't add up."

Here's my take.

{ another Stepper Motor Test

  Using 28BYJ48-12-300 Motor
        ULN2003 Motor Controller

  Theoretically, " each step is 5.626 degrees / 64 (gear reduction) or 0.087890625 degrees
  The coils are energized in 8 steps or 0.703125 degrees (8*0.087890625 degrees)
  Each revolution is 360 degrees/0.087890625 degrees/rev or 4096 steps or
  512 8-steps cycles."

  In reality, things are different.  My tests include both 5V and 12V models (ordered at the same time, marked "Stepper Motor"
  28BYJ-48).  5V Serial number 120102226.  12V Serial number...?


  Tests of both models produced nearly identical results.  My measuements suggests the step angle
  is around 0.088321893831 degrees or near 509.499944444444 8-step cycles per 360 degrees.

  These numbers are taken from actual measurements and are no doubt in error.

  This program demonstrates one method of limiting the accumulation
  of rounding errors when using integers.  Verified to produce no significant error after 10_000 360 degree cycles.

}

CON
        _clkmode = xtal1 + pll16x
        _XinFREQ = 5_000_000
Obj
    text : "tv_wtext"
VAR

Long p[8]
long pin0,pin3


PUB Main| i,j,revs,steps
text.start(12)


p[0]:=%1000
p[1]:=%1100
p[2]:=%0100
p[3]:=%0110
p[4]:=%0010
p[5]:=%0011
p[6]:=%0001
p[7]:=%1001
pin0 := 8
pin3 := pin0 + 3
steps:=0
dira[pin0..pin3]~~
revs:=0
Repeat 10000

  Repeat j from 1 to 510

    repeat i from 0 to 7
      outa[pin0..pin3]:=p[i]
      waitcnt(cnt+clkfreq/1000)
    steps++   ' steps is incremented after each 8-step cycle
    if steps > 960  '960 = 48*20 = 64*15...skip one 8-step cycle after 960 8-step cycles.  Have no idea what this means in terms of gear ratios:)
       steps:=0
       j++
  revs++
  text.dec(revs)
  text.out(13)
  'waitcnt(cnt+clkfreq)


  waitcnt(cnt+clkfreq/10)
outa[pin0..pin3]:= 0

erco · 2012-07-28 11:50

Down to $3.01 now. Where will the madness end?

http://www.ebay.com/itm/5V-Stepper-Motor-28BYJ-48-With-Drive-Test-Module-Board-ULN2003-5-Line-4-Phase-/320933811659?pt=LH_DefaultDomain_0&hash=item4ab92555cb

erco · 2012-08-04 19:31

Nice bookmarkable stepper tutorial at http://www.stepperworld.com/pgTutorials.htm BTW, these are 5-wire unipolar steppers.

ajward · 2012-08-12 09:15

The madness hasn't ended yet... $2.92!

http://www.ebay.com/itm/5V-Stepper-Motor-28BYJ-48-With-Drive-Test-Module-Board-ULN2003-5-Line-4-Phase-/170781372685?pt=LH_DefaultDomain_0&hash=item27c35cf10d#ht_3617wt_1398

erco · 2012-08-12 15:01

Good call, my young Padawan! My previous post of $3.01 was beat within 2 weeks!

Clearly you've had more time than me lately to follow up.

Martin_H · 2012-08-13 09:26

How do they make money doing this? Three dollars is less than the cost of getting a single IC (pick one) shipped to you!

RDL2004 · 2012-08-13 11:15

I'd like to know how they can ship for so cheap. It costs me $1.64 just to mail an item. That's as cheap as it gets and doesn't include the packaging. When you consider that a large chunk of the time and distance it's in transit is done by the USPS, something just isn't right

erco · 2012-08-13 13:13

I wonder how much USPS would charge if you tried to mail it back to China?

RDL2004 · 2012-08-13 14:02

For a 3 oz. First Class International package, the price is $4.56.

So, for less than $3 they can sell an item with shipping to the US included? Like I said, something just isn't right.

erco · 2012-08-14 01:45

$2.91, I'm back on top, Baby!

Now you're using my "Babies"? George Costanza

http://www.ebay.com/itm/Stepper-Motor-28BYJ-48-With-Drive-Test-Module-Board-ULN2003-5-Line-4-Phase-5V-/300733004367?pt=LH_DefaultDomain_0&hash=item4605157a4f

Martin_H · 2012-08-14 04:06

My hypothesis is that the Chinese government subsidizes the shipping cost to promote exports. But even with that I can't see how they are making money.

prof_braino · 2012-08-14 11:21

RDL2004 wrote: »

For a 3 oz. First Class International package, the price is $4.56.
So, for less than $3 they can sell an item with shipping to the US included? Like I said, something just isn't right.

Martin_H wrote: »

My hypothesis is that the Chinese government subsidizes the shipping cost to promote exports. But even with that I can't see how they are making money.

I got two separate orders delivered in the SAME PACKAGE, after one week. A third order from the same day, has not arrived yet. Definitely something about bulk shipping going on. But I wouldn't say it "isn't right".

$3 Stepper Motor & Board

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