# Stepper motors moving...WITHOUT POWER!

#### browneyedea

Joined Nov 19, 2013
1
2- Unipolar stepper motors wired (Pin to Pin) directly to each other without a power source or driver chip...Magically, I turn one and the other follows suit. Amazing!

Now I know a bit about steppers but am still a noob. A friend "turned" me on to this little known trick. As I tried it I was amazed and perplexed. The current generated by one stepper was only strong enough to move the other when spun quickly but it still lacks any real torque. So...

My question: If one stepper motor generates the pulse to move the other, can a simple circuit be created inline between the two motors to amplify the pulse from one stepper to consistently and precisely move the other without the need for a complex driver?

The application I have in mind is to have a pan and tilt platform for a camera jib/crane that could be controlled on the other end. Just looking at simple solutions for in the field use. My theory is, "the simpler the machine, the less likely it is to malfunction but if it does the easier it is to fix"...which in my experience is not a probability but an inevitability.

#### mcgyvr

Joined Oct 15, 2009
5,394
Just turning vs having enough torque to move something is different..

Joined Jul 18, 2013
28,500
You are going back to the very origin of servo's, to something called Synchro's.
You can either use an off the shelf step/dir drive which essentially amplifies the generated pulses or make a simple one that uses one pulse for step, the other direction.
Max.

#### RichardO

Joined May 4, 2013
2,270
The current generated by one stepper was only strong enough to move the other when spun quickly but it still lacks any real torque.
Even with power amplification, you may still have to turn the "sensor" motor faster than you want in order to not miss steps on the driver motor.

You can do a quick test with a DC voltmeter. Connect the motor to a pair of windings and turn the stepper _slowly_. What voltage do you get? This is the voltage that you will have to amplify in order to drive the other stepper motor