SparkFun Forums

[bdmaple]

There is some straigh cutter, but I emphasize, handled plasma cutter are NOT the one to use in a CNC or computer environment. High frequency arc starting make all electronics crazy.
There is specialized low frequency plasma. Go on a cnc forum (like cnczone), you will learn a lot.

There are also line filters and such that clean it up nice, also great grounds are a good start.

Techshop used or still uses a handheld conversion, there were some noise issues but only into the ac power lines, not to the pc, and that was remedied by a power line noise suppression device.

Basically a large capacitor and resistor, of what is called a low pass filter. but for larger power than a small circuit. same math/concept.

It used to lock up the cnc machine in the other room until this was installed.

[MichaelN]

There are also line filters and such that clean it up nice, also great grounds are a good start.
...
Basically a large capacitor and resistor, of what is called a low pass filter. but for larger power than a small circuit. same math/concept.

Yep, decent filtering, along with metal enclosures and decent groundplanes on PCBs will go a long way to resolving interference issues.

Re power supply filtering, it is normally better (and easier) to just buy an off-the-shelf filter rather than trying to design something.

[xevilstar]

Interesting ... Can you suggest some off the shelf good filters ?

There are also line filters and such that clean it up nice, also great grounds are a good start.
...
Basically a large capacitor and resistor, of what is called a low pass filter. but for larger power than a small circuit. same math/concept.

Yep, decent filtering, along with metal enclosures and decent groundplanes on PCBs will go a long way to resolving interference issues.

Re power supply filtering, it is normally better (and easier) to just buy an off-the-shelf filter rather than trying to design something.

[MichaelN]

Interesting ... Can you suggest some off the shelf good filters?

I'd start by figuring out the voltage and current you need, then searching on Digikey.com (for "filter", then select "Power Entry" or "Line Filters"). For example, for 110V / 20A, something like this might be OK:
http://search.digikey.com/scripts/DkSea ... CCM1321-ND
http://search.digikey.com/scripts/DkSea ... 64-1030-ND

There are smaller, cheaper filters such as the following, but they won't provide as much filtering:
http://search.digikey.com/scripts/DkSea ... 17-1452-ND

[xevilstar]

and that is something that goes between the power supply and the machine or between the microcontroller and the plasma module ?

Interesting ... Can you suggest some off the shelf good filters?

I'd start by figuring out the voltage and current you need, then searching on Digikey.com (for "filter", then select "Power Entry" or "Line Filters"). For example, for 110V / 20A, something like this might be OK:
http://search.digikey.com/scripts/DkSea ... CCM1321-ND
http://search.digikey.com/scripts/DkSea ... 64-1030-ND

There are smaller, cheaper filters such as the following, but they won't provide as much filtering:
http://search.digikey.com/scripts/DkSea ... 17-1452-ND

[MichaelN]

and that [filter] is something that goes between the power supply and the machine or between the microcontroller and the plasma module ?

The most important place is on the input supply line of the plasma cutter, since that is the equipment generating the interference. You could add a separate filter on the input to the power supply powering the rest of the circuit too.

You should also use good design practices for the rest of your circuitry to reduce susceptibility to interference. Things such as using metal enclosures, shielded cables and filters / protection on lines entering and leaving the metal box etc.