Let's Make Robots!

Too good to be true? (DC motor)

I found on ebay these nice looking dc motors, lots of torque and very cheap. But are they really that good?
The supplier wouldn't give me any extra info on the brand or the current consumption but they look very similair to the ones this shop sells. Also similair motors use much bigger gear ratios than this on, 100:1 is more common. 

So could this be any good?
I am planning to use them with pwm on perhaps 6 volts, but will they even run on 6v?






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Thanks for your answers!

When it comes to robot parts it's too bad I don't live in the US :) I live in the Netherlands and haven't found any good stores for motors yet. And shipping from the US is really expensive. 

 All electronics also sell nice gear motors:

http://www.allelectronics.com/make-a-store/item/DCM-288/SMALL-RIGHT-ANGLE-DRIVE-GEARHEAD-MOTOR-USED/-/1.html (even with encoder for 12 dollar!).

Those motors at All Electronics were going for $4 each on Ebay last year, I got a few. Thing is, new from Faulhaber, the motors with encoders alone are probably in the $150 each range. Possibly another $50 for the little right angle in front custom machined.

I know how you feel, a lot of robot parts are hard to get or expensive to import to Australia as well. This is why I get a lot of electronics from Futurlec, They ship world wide, they're dirt cheap with no minimum order and postage is very reasonable although very slow (usually two weeks for me).

That gearhead motor looks great for $12 and the 90 degree angle is a real bonus with metal gears. You could always remove it if you don't want the 90 degree angle. Admittedly the postage and the fact that it's used kills the deal for me.

Jaycar sell a couple of gearhead motors like that cheaper and they are an expensive store. The Jaycar motors have brass gears so are fairly good value for money. I would shop around some more.

12V motors will run at 6V but you'll only have about 1/4 of the power. 1/2 the voltage means about 1/2 the current. Power=voltagexcurrent

Those look like nice motors, and if you are running them on 6VDC it should work but at a lower torqure/rpm. I would get them, but I do not know if they have double flat or single flat output shafts.

If the supplier isn't giving you any basic information, that worries me...I guess if they're not too expensive you should just buy them and test them out...mabey make a datasheet for them and send that back to the guy.


They seem to be a reputable seller, so maybe they are that good...