eBay TB6560 Stepper Motor Driver Boards

[ccmarco]

Hi Irving,

the power section of these cards is not galvanically insulated from parallel port connection, both share same ground.

Here, optocoupling gives only a partial safety gain, because a lot of current could flow through PC ground.

So we have a "half way" protection, capable only to break direct reflow of high voltage supply on parallel port lines.

Placing high speed optocouplers, like 6N137, is not simple because they do not have same pinout.

So i simply bypassed step lines optocouplers with 270 ohms res., in future i will place zener diodes (or transzorbs) on HC14 side and i will change resistors with higher value ones, to eliminate the high voltage reflow risk.

I have to say that the full modded board behaves good, but the fix was a sort of personal challenge

Marco.

[geekinesis]

Hi
I have the 3.5 amp version of the board. The limit resistors are .15 ohm on mine. If I wanted to run .4 amp motors, what should I change the resistors to to.

I have .33 ohm resistors so was hoping to use them, but my maths isnt good with amp v etc

also is it ok to just change the resistors? As I understand the 2.5a boards are the same but with different resistors?

[dandumit]

From datasheet :
Iout(A)=0.5V/RNF(Ω)

Result : I out = 0.5V/0.15 Ohm = 3.33(3)

From datasheet tb6560 has the maximum of peak at 3.5 A.

[geekinesis]

ah great, thats what I was looking for.

So .33 ohm gives me 1.51, perfect

Also I have a 1.2A 3.8v stepper. Is there any harm in running it at 1.51A?