Re: home built controller help

Something I overlooked...

When you're checking the coil wires for the motors...
You have 6 wires, Find 3 that have continuity on your ohmmeter.
Move the other 3 aside.

Measure Resistance back & forth between them until you find
1 wire that has the same resistance between it and each of the
other two wires.

That's your center tap. This is the wire you won't be using.

Repeat for the other 3 wires.

The 4 wires left are the 2 motor coils.

John




--- In CAD_CAM_EDM_DRO@yahoogroups.com, "John Hansford" <kz1927@...>
wrote:

>
> Sorry...I read it 5 times and still didn't see that they are
>
> __6 Wire Motors__
>
> Which means they are unipolar
> which can be made to run bipolar (but not the other way around)
>
> With an ohmeter...do a continuity check on the wires
>
> When you find a wire that has continuity to 2 other wires...
> this is the center tap....mark them and put them aside...there'll
> be 2 of them.
>
> Of the four wires left, find the ones that have continuity to each
> other....these are the motor coils.
>
> Measure the resistance of each coil. They should be the same(or
> very close).
>
> I would make a few Assumptions here....
> They were running at 24 volts. So I'd divide that by 20, which
> equals 1.2 volts.....my guess would be that that is the motor
> rating.
>
> So I'd divide 1.2 volts by the coil resistance to get the
> current rating (or the Max. Amps for the motor)
>
> I would guess that would be anywhere from 2 to 6 amps(could be wrong
> though!!).
>
> To do the Gecko resistor calc's, you'd decide how many amps you
> want to give the motor. This has nothing to do with the voltage.
>
> I use about 75% of the motor rating, simply because the motors
> get HOT and it worries me sometimes.
>
> So let's say the motors were rated 4 amps(Example).
>
> I'd feed it 3 amps to start with(personal preference...75%)
>
> 47000 multiplied by 3(amps you desire)= 141000
>
> 7(amps max gecko rating) -(minus) 3(amps you want) = 4
>
> 141000 divided by 4 = 35250(the resistor you'd want).
>
> You'd use the closest rated 1/4 watt resistor.
> Probably 33K
>
> This is Only how I'd do it. There are many others here who know
> much more about it than I do. If I'm wrong or missing something
> it'll be pointed out soon enough and I don't mind being corrected.
> (Cheaper than ruining stuff!)
>
> John)
>
>
>
>
>
>
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "carlosandpeppes"
> <carlosandpeppes@> wrote:
> >
> > Hi all,i am building a controller along the lines of the one shown in
> > home shop machinist using a pmdx 131 board,3 212 geckos,40v 10 amp
> > power supply.
> >
> > I have very limited info on the motors that i am using,such as

voltage

> > and amperage,but 2 are nema 34 3.7 inches long 3.5 n/m,and one is

nema

> > 34 2.45 inches long 1.5 n/m,all are six wires.They were originally
> > getting 24 volts.
> >
> > I have limited knowledge of electronics,so a step by step way of
> > testing motors would be nice and also how to configure the several
> > jumpers on the geckos and breakout board,and the current set
> > resistors.thanks in advance!
> >
>