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John Bond
07-24-2006, 05:22 PM
Hi Guys

Your combined·assistance earlier on stepper motor ICs was very usefull. I stettled for the L6219 which does everyting except make coffee. An amazing little chip.

I've being given a bunch of 6 wire steppers. Each phase has a center tap. Connect the two center taps together and you have the standard 5 wire unipolar.

Questions:
Can I use the motor as a 4 wire bipolar stepper? Just disregard the center tap and power each pair of coils using an "H" driver·to reverse the current direction.

Do I then increase the voltage to keep the current draw the same? This means that the motors will produce more power and thus more heat. They run very intermittantly so heat shouldn't be a problem.

Kind regards·on this peacefull quiet winters·day in·Kwa Dukuza

John Bond·

Loopy Byteloose
07-24-2006, 05:45 PM
Generally, the only motors that are NOT adaptible are the 5-wire Unipolar motors AS they share one wire in common and the 4 wire Bi-polar AS they have no extra leads to play with.

The 6 wire, and 8 wire varieties seem to be able to configure as Uni-polar or Bi-polar. These can be adapted to a 4 wire or 5 wire operation.

Primarilly, the choices dictate how much holding power and how much smoothness you can expect.

Generally the current limitiations of each coil are your primary guide for voltage.· This represents that actual length of wire wound to the coil.· Measure the coil resistance and use the current rating to find the approximate expected voltage via Ohm's law.

Enamel wire is quite heat resistant and I suspect substantial leeway in high voltage breakdown of the insulation.·
[They probably use one product that is good for 100+ volts insulation·for all the voltage ratings.· Then they test for reliablity via statistical analysis.·Why should they·buy 5 volt rated insulation, 10 volt rated insulation , etc wire?· Only the gauge changes as the current changes.· The wire guage will define the current at which the wire will sef-destruct.]

If there is a maximum voltage, the weakest point may be in the tiny connections, not the coil interior.

Of course, you don't have to drive the steppers exactly to their current limitation.· You can make them run cooler if the operation is satisfactory.

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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········


···················· Tropical regards,····· G. Herzog [·黃鶴 ]·in Taiwan


Post Edited (Kramer) : 7/24/2006 11:03:48 AM GMT

John Bond
07-24-2006, 06:15 PM
Danke Meneer Herzog

That what I thought but I needed to check. The motors are plenty powerfull enough and holding torque shouldn't be an issue either. I don't even need to regulate or control the stepper voltage because the L6219 ic has a sensing resistor and pulse width modulation to control the current. Nice simple solution...

Thanks again

John bond

T Chap
07-24-2006, 06:55 PM
Is there a higher current chip with the same features? That thing is awesome but limited for applications requiring more current.

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something smells like it's on fire

Bruce Bates
07-24-2006, 07:18 PM
Originator -

What kind of ampacity and voltage were you looking for?

Regards,

Bruce Bates

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T Chap
07-25-2006, 04:03 AM
3 amps would be nice at 24v, variable down to 2 amps for other motors, I have seen other ic's that will do it, but none as cool as that one above. Obviously in one ic there is too much heat to dissapate.

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something smells like it's on fire