[cnc kiwi]

Hi
I have a fairly standard L298/L297 stepper motor driver board that seems to work perfectly except for one thing which I'm wondering if it's normal or not.
When I enable the drive and step the motor a kind of liquid gurgling noise emanates from the stepper motor as though the electricity was acting like water or something. Is this supposed to happen, or if not is it easily fixed? My guess is that it's something to do with the chopper in the driver board and the motor maybe not getting the right amount of current.

Thanks
Cnc Kiwi

[Khalid]

contact EMMKAY..he worked on L297/L298 boards...also contact www.pminmo.com

[unterhaus]

I think that's fairly normal. They definitely make some strange noises

[rippersoft]

That's the chopper frequency. My HobbyCNC board makes a hissing sound until the motors actually step.

RipperSoftware

[vroemm]

When I enable the drive and step the motor a kind of liquid gurgling noise emanates from the stepper motor as though the electricity was acting like water or something.

I had the same problem.
Sounds like meat sizzling in a hot frying pan.
Very irregular.
And i lost steps, which was greatly dependened on the setting of the current limiter.

All the time i had CONTROL pin 11 LOW.
Like in the http://www.pminmo.com/ circuit.
Then INH1 and INH2 are used.

Then i set CONTROL pin 11 HIGH, with pull up resistor to +5 volt.
Now it acts on the phase lines ABCD, what ever this might mean :-)

Problem solved.
Still soft noise, more regular noise, much less noise.
No more steps lost.

The L297A is a newer version of the L297.
The datasheet http://micromouse.cannock.ac.uk/motors/L297.pdf
says the L297A has no CONTROL pin 11.
Because it is not needed, the datasheet says.
The L297A acts always on the phase lines ABCD.

If it is good enough for the newer version L297A, then it must be good enough for me, i figure :-)

[pminmo]

The L297A was made for small stepper motors in floppy drives. Holding ctl low while noisier improves the top speed of most motors, vs phase inhibit.

[vroemm]

Holding ctl low while noisier

Don't you find this noise annoying ?
So irregular.

improves the top speed of most motors, vs phase inhibit.

My ISERT 3455 steppermotor goes faster with CONTROL HIGH.

[pminmo]

Steppers can be noisy, some more than others, some pairing (motor and driver) worse than others. Noise on one driver and motor maybe completely different with a different motor. They vary significantly on supply voltage also. What you are hearing is most often the chopper frequency, or the beat note of the two phases of choppers asynchronously running (i.e. one 2 phase motor). Now as you go up in complexity of drivers, and typically cost, there are methods to lower the noise. With a spindle running and cutting, stepper noise is a non factor.

As to your motor running faster, your motor may have the electrical characteristics that it needs a slower decay to gain torque. That could also be because of the chopper frequency choosen is to slow also.