Hello, I am better trying to understand how brush-less steppers work. For the most part i understand how a 3-wire BLDC ( the kinds for drones) work by groups of mosfets in an ESC, switching on and off to energize each wire at a time very fast.
but,
now i want to learn how steppers work and what it takes to get them to spin. I came across an old stepper that i had stripped from a cd player a long time ago and dont have specs (Pic of stepper below)
but i have taken a multi-meter to each wire and what i have noticed is that between any wire and black i get 0.0 ohms and any two wires besides black get 0.2 ohms, so i dont know if black acts as a reference or ground??
When i take 9v to two wires, i am able to get it to move but i cant figure how to keep it going in one direction and what type of signals is sent to the pins and what type of hardware does it take to get it to operate fast?
Thanks
They work basically the same as BLDC except for the "very fast" part, and with usually a few more steps for a full rotation.
Hi,
Have you googled stepper motor basics
There is a mass of written and video info on how steppers work and how to control them.
Tom.. 
That's a 3-phase motor (wye winding plus common), not a stepper. Black is common.
Steppers have two (or more) electrically separate windings.
MarkT:
That's a 3-phase motor (wye winding plus common), not a stepper. Black is common.Steppers have two (or more) electrically separate windings.
Thanks for reply, so would this be something like a BLDC like the kind used for drones, with something like a ESC to power it, or does it work light an A.C fan where the frequency sent to it controls it? and does that motor need a special driver to get it to run?
so would this be something like a BLDC like the kind used for drones
No, its got a common wire, its a wye wound three-phase motor with the common point
brought out - it can be driven unipolar or 3-phase.
RC BLDCs are three-wire, extremely low impedance. Basically intended for 10A to 100A
or so, high power + high speed at low voltage. That pictured motor is high impedance,
low power, low speed.
Most steppers have separate windings (bipolar) and are intended for independent
current-control loops for each winding - they are actively current driven for microstepping.
The way steppers work is deliberately inefficient, most of the time they burn up power
just to hold position, not to do work. Due to the extreme pole-counts in a stepper (50 pairs
of poles is common), top speeds are not particularly high, and winding impedance is
the dominant property for performance. Most BLDCs have a handful of pole-pairs, seldom
above 7.
Other motors are designed to do work, not hold position, so cogging forces are kept low
for them (steppers have large cogging force typically).