Let's Make Robots!

What type of motors are these?

I recently bought some motors of ebay.  They have opto couplers on them and they are a decent, see the picture.

How do I tell if they are stepper motors with encoders or servo motors with encoders?


Motors.jpg202.2 KB

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Searched E-bay for a DC motor with encoder and found this. http://www.ebay.com/itm/Small-D-C-Servo-Motors-with-Encoder-and-Gear-Box-/280618623201?pt=LH_DefaultDomain_0&hash=item41562c60e1 I also noticed that it took up to 24v, so your assumption there was correct.

if those are dc motors, then WTF are the extra leads for???

Maybe it could be just a built in tacho?


See new pic

oh yeah that makes sense.

apply some volts to the red and black and see what happens...

yep I put 12v and she spins, although very slow hey.  Might be a 24v motor?

So any ideas on what volts to plug into the infra red? opto thing?  I have seen some circuit showing the use of a resistor obviousl as not to blow the LED up.  But how will I work this out my my unknow one?


well if u can figure out what the emitter is u can try 5V @ 0.020A, thats typical for leds.

or if u have a decent multimeter, the diode test function might be able to light up an LED.

the output will be either variable (when u spin the wheel) current or volts. if current you have to make a volt divider with
the receiver acting as one half of it to get volts out so a micro can understand it as 0 and 1.

u can detect IR light with a digital camera.

if u can see the actual leds, the receiver might be dark.
some receivers have a casing that filters out non IR light, u might be able to tell which is which from that.

since leds are essentially diodes, i think u can use a multimeter to check polarity.






Yes I have had steppers in the past 1200oz down to 270oz, actually have some 270oz left.  I just bought these on ebay cheap and have just starting buying heaps of electronic parts and a scope.


So how can I work out max voltage on these?

It's not a servo, sure, you can make one, but it's going to be difficult if not impossible(I don't know how much you know) it's simply a DC motor with an encoder, this is useful for locomotion on a robot, but you can't directly attach the wheels to motor, you'll need some form of gearing to bring down the speed and increase the torque.

I really doubt it's a stepper due to its shape and the openings in the metal. 99% sure it's a DC motor.