3 digit current meter

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sandyL
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Joined: Fri Feb 03, 2017 3:43 pm
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3 digit current meter

Post by sandyL »

I have the meter installed and when on idle, it reads 00.0 but when cutting it will jump to EE.E, and bounce around. Seems to cut very hot.Can someone tell me what I have done wrong. Every thing is new except tube.
Any comments are welcome.

confused sandy
daniel.macke
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Joined: Mon Jul 28, 2014 10:30 am
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Re: 3 digit current meter

Post by daniel.macke »

Hello,
"EE" should mean that the reading is out of the meter range (0-100mA) : check the polarity between the blue and green wires. The blue should be connected to the laser tube and the green to GND. I have noticed that these meters can display negative values, but with a reduced range (10mA?)
This can explain the "EE "...
Regards
Daniel
Techgraphix
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Location: Appelscha, the Netherlands
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Re: 3 digit current meter

Post by Techgraphix »

Does this meter needs a shunt? Say it is build to read up to 1.999mA, for instance, there should be a shunt-resistor, of a given value (see datasheet of the meter), across the input..

Kees
sandyL
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Joined: Fri Feb 03, 2017 3:43 pm
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Re: 3 digit current meter

Post by sandyL »

The shunt was the problem, I thought using the 5 volt output on the PSU would work but I guess it did not like that. Re wired using the shunt and it seems to be fine, now if I can figure out how to get to the um calculator and get that to work and stop the "out of bounds" message . I may be on the go if you can tell me how to get to the calculator.


Thanks guys for the help
Sandy
Techgraphix
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Re: 3 digit current meter

Post by Techgraphix »

Out of bounds can have a few causes:
1) your lasers physical borders differ from what you have entered in the software OR your homing sequence is not correct.
2) more likely: If you want to engrave near the sides of the laser you did not leave enough space for the head to accelerate:
Say you want to engrave with 500mm/sec and the acceleration is quite low, you need a long distance to get the head to the desired 500mm/sec. Depending on the acceleration this can be easily over 10cm.. If your object is closer to the boundary than this 10cm, you will get the message "out of bounds"
You can solve this by placing the object more to the middle, or increase the acceleration/lower the speed..
For high accelerations you must have a strong build machine and very strong high speed motors. My machine can accelerate with 5G!! without problems. Not entirely true: i had to reduce the acceleration as my 200kg machine started "walking" through the room. it is also better to reduce beltstretch as i only have 10mm wide GT2 belts...

Hope this helps..
Kees
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