Hey guys I was wondering if someone could shed some light on what this device does? I am looking into using a stepper motor and it seems that this is used to drive it. What is the funcitonailty of the transistor in this set up? Is it amplifying so that a greater current can be used to drive the coils or is it acting as a switch?

Thanks

 

Hello,

Do you have a schematic?
Without a schemetic it is a lot of guessing.

Greetings,
Bertus

 

neeevermind i found a good explanation of what they do! how do i take down a post?

Thanks anyways!

 

I lied still need some help! So if anyone could explain what this BJT is doing that would be great

 

The schematic is incorrect.

Normally, when using the stepper in unipolar mode, +V would be applied at the center tap of each side of the motor's windings (you have them identified as 2 and 5), and a Darlington or power MOSFET would be used to sink current from either end of the winding.

As things are connected now, D1 is connected backwards (cathode should be on connection 2, anode on connection 1) and Q1 is simply shorting out the winding.