A stator tester : CX8000 | |||||||||||||
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To bad, to see my "Red Rascal" standing there, without it's engine.
Where did I put the results from the last stator measuring, now I have to
do it all over again. But what the h.... I have nothing else to do,
except waiting until the money train comes in. So I go and measure the
values again, and write them .. oh sh#t, I forgot my pencil...
There must be an easier way to do it. It would be nice if there was a statortesting divice, one to connect to the computer and that it would show the values from the coils on the screen and save them. But it doesn't exist. Maybe I can..... I find out quickly that measuring low resistance is an special thing. The simple beginning is of course U1:U2=R1:R2. That will be the starting point. That and one of the two Vellemann K8000 I/O cards that are gathering dust somewhere in a box. I get started, but whatever I try, I always get wrong values from my testdevice. A fully automated statortester requirers an extra relay card, to eliminate the voltage drop acros some components, and that will be to costly for this lowbudget project. After all, a new stator is more important than a "hobby project stator tester." But can I build a semi-automated testers? I find out that that is possible. But I need a double 8- or 12-position rotary switch. The first halve to do the actual testing, the second halve to tell me what I an testing. Using one from four AD convertors that comes build on the K8000, I can read the total voltage across a serial circuit, consisting of a reference resistor and coil. A second AD convertor will be used to measure the voltage after the reference resistor. Therefore I can calculate the voltage drop across the reference resistor, wich has a know value. And so I can calculate the current that flows trough the resistor. And because resistor and coil are connected in serie, I now can calculate the resistance from the coil. In a formule it looks like this Urref=Utot-Urx, next Itot=Urref/Rref followed by Rx=Urx/Itot and to make things more complicated I can write this as: where
That is the theory. But does it work in practice ? The test bench, made out from loose wires and testpins funtions well on three sample resistors. The test program, 'quick and dirty' put together works also. All the loose end are know build together to become the worlds first semi-automated cx-statortester. Wires are put together, resistors soldered, connections are made. | |||||||||||||
 ... a semi-automated statortester... |
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The computer program is adjusted, so it lookes better. The tests, on the
attic, gives good results, that is, the results are what I expect. Now
it's time to put this whole contraption to the test. I could not find
the right Honda connectors, and I am forced to use single connector-pins.
The real test is to connect the statortester to the "Red Rascal's" stator,
from wich I know the values like the back of my hand.
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 ... connect the statortester ... |
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An old laptop computer is placed into my shed, and onto the printerport
the statortester is connected. Power on, start program and than....
Turning the rotary switch (the semi- part) one by one the values from the stator apear on my screen ( the automated part). It Works!! The first results are good. Here and there I have to change field names, but beside these minor mistakes this version of the CX8000 software is good enough. I don't have the values from the three generator coils, but that is not difficult to add to the tester. So far I'm very satisfied. |
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 ... the first results ... |
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There is one problem. With a simple multimeter and a blocknote I could
achieve the very same result in about half an hour, and now I was busy
for more than a week.
But the great advantage from this device is, that given the right connectors, I can get the stator values from any given CX500z,a or b in just a few seconds. I want to make some adjustement into the program, like a field for the licencenumber, the possibillitie to store or even e-mail the results, and to print them on paper. Always more things to do, if not with the CX, than with the 'side-effects'..... |
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