Converting a THCAD-300 to a THCAD-10?

Hi, having the same problem, want to convert my THCAD 300 to a 10, ive got the resistors but dont know how to recalibrate, how did you recalibrate yours?

I used an external power supply and an oscilloscope, but you could use a 9 volt battery and halscope. Here's someone that did just that
forum.linuxcnc.org/plasma-laser/35065-thcad-10?start=40

Hi,

Im ready with soldering, is a Fluke 179 Multimeter also okay for calibration?

And for Calibration i connect my multimeter on FO+ and FO- power up the THCAD 300 (now 10) and connect the powersupply with 10v on IN + and -?

sorry for my stupid questions, but this is my first project with linuc cnc and mesa components, also my english is not the best and i dont realy know how to config everything in this HAL thingys, but i read as much as i can in this forum.

You also need to supply +5V to the THCAD on the low voltage side (it's marked). The other connections are correct. Pay careful attention to the 10V signal you're connecting to IN + and -. It doesn't have to be exactly 10v (a 9v battery will do, but may hover ~9-9.5v), but you need to use that voltage your calibration calculation. Use linear interpolation/extrapolation to calculate the frequency output at 10v. You'll know you're in the ballpark if you get similar values to the original sticker on the -300.

Then you can use this calculator to set the scale and offset values for plasmac. jscalc.io/calc/NTr5QDX6WgMThBVb

The Fluke 179 says it can measure up to 100 kHz signals which won't work with the card while in F/1 mode. You'll have to change it to F/32 to get the signal slow enough to what your meter can read.

Ups, was reading HZ instead of KHZ...

But with f/32 it worked well with the Fluke, big thx!!!

now back to read how to get this HAL pins to configure plasmac...

PCW wrote: The 10 through-hole resistors on the THCAD-10 and THCAD-5
are 10K .1% . The 10 through hole resistors on a THCAD-300
are 300K 1% HVR (3500v rated)

The THCAD-5 input current to voltage converter feedback resistor is 49.9k
0.1% The THCAD-10 and THCAD-300 feedback resistor is 24.9K 0.1%

may I ask which is the current to voltage converter feedback resistor?

thanks