THC TX Impedance (Matching)

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chronolite
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THC TX Impedance (Matching)

Post by chronolite »

Client and I arer about 50% done with our plasma build and getting to the part where we connect the voltage divider from the Everlast 62i in an effort to make it part of the compatibility list. I wish we could have purchased a Powermax, but they're not even available for months and well, plasmas gotta plas.

What I'm concerned about is the THCTX internal voltage divider and if that will change the output ratios on this circuit. If the TX uses a voltage divider on it's input end, then well, won't our voltage ratios will be off?

This is a common problem with Langmuir thc and other different THCs, there are work-arounds, but they involve using a power supply and doing the measurement, or jumpers, inline resistors etc, so I'd like to get ahead of the game on this. (Here's an example where my concern arises: https://www.plasmaspider.com/viewtopic.php?t=23700)

The Everlast 62i is 88-108v output range. As you can see in the note, there are two 100kΩ resistors inline with the raw output voltage as well. Based on this, I'm assuming that the 15:1 and 50:1 are also in the 10-100k range.

I'm wondering if we can confirm the TX has a certain impedance on the inputs and what that range is? Is that somewhere and I missed it in the documents?
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62i cnc pinout.pdf
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jcoldon
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Re: THC TX Impedance (Matching)

Post by jcoldon »

acorn You can't use raw voltage . looks like pin 4 pin 6 50 to 1. make sure you connect the pos and neg correctly pin 6 pos pin 4 neg
acorn thc anlv would be pin 4 ..... pin 6 would be gnd on thc bord.... use the plasma thc wiring diagram right now acorn supports Hypertherm
so i assume your on your own try this. if the voltage is not in the operating range i assume the thc calibration wont work . i guess you have to try this let us know what happens... personally i see no reason why it will not .... Just make sure you have it correctly in 50 to 1 output . NO RAW VOLTAGE
cnckeith
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Re: THC TX Impedance (Matching)

Post by cnckeith »

please see the draft install manual.
page 18 shows THC config. you can set the divider ratio there.. we default to 50:1 and that is preferred.
https://www.centroidcnc.com/centroid_di ... manual.pdf

there is also a THC voltage calibration macro that runs during setup to calibrate the Voltage.
follow the system instructions on how to set up starting on page 3 in order.
Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
All Acorn Documentation is located here: viewtopic.php?f=60&t=3397
Answers to common questions: viewforum.php?f=63
and here viewforum.php?f=61
Gear we use but don't sell. https://www.centroidcnc.com/centroid_di ... _gear.html
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