Newbie: Need help with stepper motors pulled from printer

[bossxero]

Hi all Folks.

I send my great appreciation to all the members and gurus of this fantastic board.  After weeks and weeks of reading about epower stuffs, i finally decided to get my hands dirty.  I made my mind to make a small windmill since I am currently on holidays. As I had two old Lexmark Z11 printers(under the bed), I dissassembled them and took off the motors from them in order to use them as generators.  In all I got four stepper motors but there were no voltage or anything printed on them except 7.5ohms-7.5step, 8ohms,61ohms respectively and nothing meaningful on the fourth.  

My first problem that am currently facing is the I cant figure the positive and negative terminal of the motors.  3 of them has four wires and the fourth one has 5 wires.  Its a real mess in my mind,I try to run them with a battery but it wont turn, so my question is, HOW DO I FIGURE OUT THE WIRES THAT I SHOULD USE AMONG ALL THESE?  

Am stressing again, am a newbie in this matter, so please, am expecting a lot from you guys. And I know that i wont be disappointed and awaiting for your troubleshooting.

Thnx

[pyrocasto]

You should try searching on google for the part names and numbers. I found the info I wanted on mine from my printer, and found one was 42v @ 3amps. Not a bad little genny.

As for the wires, I've got some with 5 wires, so I'm in the same boat. On one of my 4 wired ones though I found 2 of the wires read on the voltmeter when I spun it, and the other 2 did not. Play with a voltmeter and see what you can find.

[David HK]

This site should help you.

http://www.thebackshed.com/Windmill/images/stepperwire.gif

Dave HK

[Jon Miller]

I believe that if start by using an ohm meter to find out which wires are what resistance.  The higher the resistance the larger the number of coils hens the increased ability to produce higher voltage at a set RPM.  I think if I remember correctly that one of the wires is affectively a positive wire and the others are tapings of the windings.  Stepper motors produce Alternating Current AC which has to be rectified using diodes.  Also knowing that Volts = Current X resistance and knowing the resistance and knowing the voltage you want to produce say 14 volts and say your resistance is 8 ohms Current = 14 Volts / 8 Ohms = 1.75 amps which will give you a good idea of  output of the motor .  The other advantage with stepper motors is the fact they have no brushes to wear out.  Hope this helps some how

[richhagen]

The four wire steppers are probably a bi-polar type stepper motors, and the 5 wire is probably a uni-polar type stepper motor.  A little basic information on the way these are wired is here:

http://www.cs.uiowa.edu/~jones/step/types.html

Because of the way these are wired, they don't necessarily have positive and negative leads as such.  The controllers for the bi-polar ones actually reverse the polarity of the voltage across the coils during operation.  The magnets are mounted on the rotor, and depending upon which phase of coils is energized, and its polarity, the rotor will rotate a finite amount, or a step, to line up the magnets with the electromagnets created when energizing the coils.  Hence the name 'stepper' motors. Most printers and floppy disc drives contain these types of motors, as well as my small CNC mill which I use to carve small wind turbine blades.  

For the motors with 4 wires, you should have a lead from the ends of each of two coils that make up the phases of the motor.  If you connect an led between the leads and spin the motor by hand, you will most likely see the led light if you have the leads from each end of the same coil connected.  The output from the coil will be AC, but for half of the time it will be the right polarity for the LED.  For a simple generator, you can use 8 small diodes to build two bridge rectifiers to rectify the output of each phase to DC, and then connect those outputs in parallel use that DC power for some interesting purpose of your choosing.  You can also hook an electrolytic capacitor across the output of each phase and then series the output for a higher voltage at lower amperage.  I have built little wind turbines with small stepper motors and 1 foot blades.  They don't put out much power, but they are a lot of fun.  They would be simple to build for a classroom project, much like Ghurds recent post on the VCR motor turbines, or for a first experiment with wind power.  Most of the tiny motors in cheaper printers use bushings instead of sealed ball bearings, so I am not sure of the life expectancy in a wind turbine, but you could make a small hand crank led flashlight that would likely last a lifetime.  Rich Hagen

[richhagen]

Where I said 'you can hook an electrolytic capacitor across the output of each phase' above, I meant to say 'outbut of each bridge rectifier'  Each bridge rectifier is rectifying the output of one phase of the motor.  

[richhagen]

Those diagrams should be applicable to the steppers in the Lexmark printer.  Rich

[bossxero]

Thank you all for the nice replies.  But they seem to be too technical and I cant understand it well.  Well, I took the motor with four wires, I spin it with the fingers and it spins with a 'slight' cog, but when I connect 2 wires in pairs (orange+yellow)and leave the other two as is, the cog tends to becomes more 'harder'.  It I connect them in 2 pairs (orange+yellow and brown+black), when i pin it, it becomes 'smoother' and the cog cant be felt well. Do anyboy have an idea about that?

Regards

thnx

[coldspot]

Wecome to the board

Measure resistance between each set of wires, write it down

this will let you figure out whats hooked to what.

center of coil will be half of ends of coil.

like 5 ohms while ends of same coil would be 10 ohms

Do a board search and read thats how I learned how to wire them and now

getting three more ready I just picked up from my brothers place.

ones a 5 wire another is 8 wire and the third is still not letting the belt pulley

off so its in another room and can't get myself to walk that far tonight

have fun  

[ghurd]

The 4 wire type have 2 sets of coils, and the backshack wiring diagram is good.

The 5 wire types are also 2 sets of coils, and each set has a wire to the center of each coil and those are connected together inside with the 5th wire.

I have very poor results with most 5 wire steppers.

The best I have done with most 5 wire steppers is a single diode with the strip towards positive, in each of the 4 coil end wires, the stripe ends of the diodes are connected to each other making the positive, and the 'center tap' wire is negative.

So far, this gave me higher output than the 5 wire backshack wiring diagram.

For 5 wire steppers, Any wire (coil end) to the center tap wire, will have the same ohms. Coil end to coil end will have a higher ohm reading.

There are a lot of unusual steppers. Some work better one way and others work better another way. Some don't work at all!

G-

[asheets]

I don't know if many of these are round anymore, but when i was starting out in the computer industry you could obtain a large number of old noisy daisy wheel and dot-matrix serial printers really cheap at auctions.  I mean these would be the large (30 inch) platen types, and so noisy that they had to be installed in a seperate cabinet to keep them quiet.  You could pick them up for $1/pallet at the old DOD auctions (I lacked a forklift and a truck back then, so I didn't partake very often.  I only bought the pallets that I could break down and fit in the hatchback of my old Plymouth Champ.).

I never bothered to test this (since I was more interested in getting them working as printers than taking them apart) but those old, huge stepper motors could probably make decent generators today.  The motors usually ran between 48 and 250 volts.

[bossxero]

Thanks for all these replies and comments.  Finally I was able to grasp the concept, anyway I think I did grab it.  I've not been able to find the relevant info about the  motors on the net, but with a multimeter and lots of patience, I was finally able to figure out the terminals of two steppers.  I wired each one in turn on a testboard and plug a 6v mini-bulb with it, twist the spindle with my fingers and it LIGHTS up brighly.  When testing the voltage with the multimeter, am getting 6volts+ just by twisting the spindle with the fingers.

So I thank you all for your nice help.  Now I have the other two steppers which I have to work on to find the terminals.  Anyway its lots of fun doing it, especially when we see the juice coming out :-)

Now I have plenty of ideas in my mind for these motors(as they seem to be v.good as generators) and I hope that I will be able to materialize these ideas in the near future.

Again, thanks to all.

[Chagrin]

Geez you're making it too difficult.

With the bipolor motor, just test for continuity between the four wires and you'll come up with two pairs. You'll need two bridge rectifiers -- with your pairs connect them to the AC leads of the rectifiers (the two wires of each pair stay on the same rectifier). Then connect your lightbulb to the +'s and -'s of the rectifiers. Done.

[bossxero]

Thanks CHAGRIN for the tip.  Infact its really not that difficult to figure out the wires when we check for continuity.  And this is what I did and got the two pairs of two stepper motors.  For that part its ok.  

The thing that I did not well understand is the rectification and bridging.  Could you detail it to me please.  With some diagrams if possible(and not schematics since its all greek to me :-) ), if its not too much asked.

This board is really very very helpful, i mean not the board itself, but the Gurus :-), the answers and suggestions that we get almost instantaneously are very helpful and motivating. I like it.  Thank you all for that.

Regards,

Thnx

[ghurd]

Do you have a bridge to look at? This really is easy stuff.

There are a few kinds of bridges.

They all have 4 connections, 2 in, 2 out.

The AC from the stepper goes into the terminals marked ~.

The positive terminal is usually different somehow. Longer wire, sideways to the others, a notch off the corner... or a big + next to it.

so 2 wires from a coil go to the 2 terminals marked ~.

the 'different' terminal goes to battery positive.

the other terminal goes to battery negative.

It takes a bridge for each coil set. Most steppers need 2 bridges.

With 5 wire steppers, the 5th wire can cause some problems.

It doesn't look like it will on paper, but the meter shows it does.

I sometimes get more power out of either coil, than when both are connected!

Bridges have losses.  For just lighting a bulb, not charging a battery, it will work better without bridges, just connect the AC out pairs each to their own bulb.

Most steppers seem good for voltage, but not good for amps. A bulb rated at 3V and 150ma is not going to work as well as a 6V 75ma bulb. A 9V 50ma bulb may be even better.  Even though they are all 0.45 watts.

VxA=W and 3x0.150 = 6x0.075 = 9x0.050 = 0.45 watts

Radio $hack has bulbs in the store with the voltage and amps listed on the package.

[ghurd]

AC from the motor goes back and forth. No matter which side of the AC input is positive, the output side is always the same polarity.

http://en.wikipedia.org/wiki/Diode_bridge

G-

[bossxero]

Thank you. I've finally been able to mount my bridge rectifier  and it works. am getting good DC ratings, practically no loss through the  diodes. I've got the diodes from a bad computer power supply. I suppose they are schott diodes.  Little by little, am getting it. And I owe this to all of you here. Thank you.

Another matter now.  My stepper is generating at a normal spin, about 5vAC, and after rectifying, am getting about 4.x vDC.  How do I do to increase the voltage, is there a voltage doubler thing which i should do? I would like to be able to charge batteries with it. So how do i do?

Another thing bothering me from time to time, can a capacitor replace a battery? I mean substitute a capacitor in the place of batteries such as in toys etc?

Awaiting your comments and ideas. Thanks.

Regards

[ghurd]

Careful now!  There are only so many watts.

A transformer can double the volts, but make half the amps. Same watts.  And I'm quite sure you don't have much amps to begin with.

And nothing is perfect. The transformer has losses. Meaning it uses some of the watts.

I would suggest another stepper motor. 8 to 16V and 4, 6, or 8 wire. Lowest ohms you can find.  About the best I have (and I have a LOT) is a grey Step-Syn for IBM 24V 0.18A, type 103-771-18, 5-wire (I know I said avoid 5),on ebay, starting/selling at $9.99. Severe cogging.

It can break 100V by hand, meaning my daughter will no longer hold test clips.

Probably be OK with a 20" box fan blade, but a metal blade 'resonates', Hehe.

But it still can hardly break 100ma 12V. 1.2 watts.

For a cheap, easy, working and homebrew first try, I would suggest a small induction conversion.

Capacitors can be used as batteries. But they have to be HUGE, really huge, and really expensive. Not practicial.

G-

[ghurd]

Forgot, They can be very useful for charging batteries, 3 or 6V.

Some steppers will make 200ma at lower voltages without much trouble or wind.