computer control machine pot

[Karl_T]

My plasma cutter has a pot to adjust the power level.

I'd like control this pot through the CNC control. The CNC control can ouput an analog voltage signal -10 to 10 V. Or, it can turn on outputs. Five outputs can be used to provide 32 levels (2 to the fifth).

i have no experience with electronic device design. What sort of device would fill this need?

Karl

[jalessi]

Karl,

CNC4PC makes a pot driven control board that would do what you want.

http://www.cnc4pc.com/Store/osc/prod...roducts_id=179

Give Arturo a call:

Arturo E. Duncan

1337 SW Sultan Dr.

Port Saint Lucie, FL 34953

Phone:561-208-6664

Fax: 772-905-4387

email: aduncan@cnc4pc.com

Hope this helps,

Jeff...

[Al_The_Man]

There may be a simpler approach, pot inputs can usually be substituted for a varying voltage between the common terminal and the pot slider input, you would have to check the voltage across the outer ends of the pot to find the max voltage seen at the slider input.
There is a possibility to use an analogue input direct, or if the voltage required is larger than the analogue signal available, or it is not feasible to use a non-isolated approach, then maybe a OPTO IC such as H11F1 could be put to use.
This OPTO accepts a varying voltage and the output simulates a varying resistance depending on voltage in.
The input to the Opto may load the analogue signal up so a unity gain op amp may have to be used together with the H11F1.
Al.

[jalessi]

Al,

Would a MAX5450 digital pot work?

http://datasheets.maxim-ic.com/en/ds...50-MAX5455.pdf

Jeff...

[Al_The_Man]

I would think in this application it would be tricky, it is more suitable for processor or discrete logic control as it requires a known pulse train to control the wiper level.
It also has no isolation if that is what is needed.
Interesting chip though.
Al.

[Karl_T]

Originally Posted by Al_The_Man ... a OPTO IC such as H11F1 could be put to use. This OPTO accepts a varying voltage and the output simulates a varying resistance depending on voltage in. The input to the Opto may load the analogue signal up so a unity gain op amp may have to be used together with the H11F1. Al.

here's the data sheet.
http://www.fairchildsemi.com/ds/H1%2FH11F1M.pdf

Looks to do exactly what I'm after. I'm using a galil card for the signal voltage. Galil calls these analog inputs but the host control has a way to set these as analog outputs. Don't know how its done, not seeing anything in the galil manuals. Anyway, do i need a unity gain op amp? More importantly what is this device and exactly how would i wire it?

Karl

[Karl_T]

Originally Posted by jalessi Karl, CNC4PC makes a pot driven control board that would do what you want. http://www.cnc4pc.com/Store/osc/prod...roducts_id=179 ... Jeff...

Thanks for the info. I'll go this route if i can't figure Al's simpler approach out.

Karl

[Al_The_Man]

I am away for the weekend, I will be back Tuesday.
Did you check the voltage on the pot and does the unit show details of the pot input?
Al.

[Karl_T]

Originally Posted by Al_The_Man I am away for the weekend, I will be back Tuesday. Did you check the voltage on the pot and does the unit show details of the pot input? Al.

There's no rush on this. its got 24 volt to a 2Kohm pot.

Karl