eBay TB6560 Stepper Motor Driver Boards

**Tom** · 18-11-2009

Originally Posted by irving2008

Can you turn down the power supply? Mine goes down to 32 and up to 40v. it could be that back-emf from the motor had damaged the chip by spiking the supply - I'd limit that board to a 30v supply if it has regulators on-board unless they have an additional dropping zener diode in series. On my board you can see spikes of 65v on deceleration, so I have a snubber (basically a 36v zener and a low ohm resistor) across the supply. Another solution, shown in the attached schematic uses a transistor to the same effect...

Hi Irving,

That snubber circuit is very interesting... It's just what I need. I'm running one of those 50V power supplies that Kip found in "unregulated" mode at 43V. My drivers will smoke at 50V, so I'm nervous.
Can you point me towards any online material that would help size the components to dissipate the sort of spikes I'm likely to see?

Sorry to hijack! (maybe Irving's tip will save a few more driver boards... :)

Tom

**irving2008** · 18-11-2009

Originally Posted by Tom

Hi Irving,

That snubber circuit is very interesting... It's just what I need. I'm running one of those 50V power supplies that Kip found in "unregulated" mode at 43V. My drivers will smoke at 50V, so I'm nervous.
Can you point me towards any online material that would help size the components to dissipate the sort of spikes I'm likely to see?

Sorry to hijack! (maybe Irving's tip will save a few more driver boards... :)

Tom

Tom,

Yes, sadly I wasnt able to find an easy way to turn the volts on those down as they do some strange things with the internal reference line that doesn't follow the application note for the chip they use. I managed to blow one up quite spectacularly!

When I said zener diode I really meant a transient suppressor diode (transorb), such as these from Vishay. But i think clamping to 50v from a 43v supply might be tricky. A zener will clamp, but wont catch transients. you could use a 47v zener as a clamp with a 48v transorb in parallel to catch spikes, with a series low ohm resistor as a current limit between the supply rails. Farnell sell the transorbs, about 30p a go.

**Tom** · 19-11-2009

Originally Posted by irving2008

When I said zener diode I really meant a transient suppressor diode (transorb), such as these from Vishay. But i think clamping to 50v from a 43v supply might be tricky. A zener will clamp, but wont catch transients. you could use a 47v zener as a clamp with a 48v transorb in parallel to catch spikes, with a series low ohm resistor as a current limit between the supply rails. Farnell sell the transorbs, about 30p a go.

Thanks Irving!

That's just the right amount of info... I REALLY don't want to smoke these drivers, so I feel some internet research, followed by electrickery, coming on....
There's time because I'm not cutting in anger yet - just aligning, and debugging....

Cheers,

**Mad Professor** · 20-11-2009

Today I have been able to find some free time to do some basic current testing using my bench power supply, and USB Oscilloscope.

Using the oscilloscope across the current sence resistor I get the following results.

Bipolar Parallel
DIP Switches 1-2
ON/ON: 0.469v avg / 0.33ohm = 1.421a.
ON/OFF: 0.313v avg / 0.33ohm = 0.948a.
OFF/ON: 0.234v avg / 0.33ohm = 0.709a.
OFF/OFF: 0.078v avg / 0.33ohm = 0.236a.

**irving2008** · 23-11-2009

Originally Posted by Mad Professor

Today I have been able to find some free time to do some basic current testing using my bench power supply, and USB Oscilloscope.

Using the oscilloscope across the current sence resistor I get the following results.

Bipolar Parallel
DIP Switches 1-2
ON/ON: 0.469v avg / 0.33ohm = 1.421a.
ON/OFF: 0.313v avg / 0.33ohm = 0.948a.
OFF/ON: 0.234v avg / 0.33ohm = 0.709a.
OFF/OFF: 0.078v avg / 0.33ohm = 0.236a.

That looks about right... i assume by average you mean RMS, so the peak current will be around 2A. Can you post waveforms as discussed?