Re: [CAD_CAM_EDM_DRO] I'm confused, which are better uni or bi polar ?

JanRwl@... wrote:

> Dave!
>
> All else being equal, a bipolar beats a unipolar hands-down! The only
> "disadvantages" are you require a DUAL-polarity supply (i.e., instead of just
> "plus and minus", you need "plus", "Common", and "minus".

No, you don't need a minus supply. Any way you build it, it takes more
transistors to make a bipolar driver, but transistors are pretty cheap, today.
You need 4 transistors for each winding, 8 total for each motor. A pair
of transistors are connected to each wire, one to pull that wire to the plus
supply, one to pull it to the ground (or minus). When one end of the motor
winding is pulled to +, and the other to ground, current flows one way. If
the transistors are switched the opposite way, then current flows the
opposite way through the winding. This circuit is called a full-bridge or
H-bridge, due to the way it is conventionally drawn.

So, it can easily be done with only one power supply.

Jon