Re: [CAD_CAM_EDM_DRO] Re: Router spindle electrical noise.

It appears there has been a consensus that this problem would be fixed with
shielded cable. It has worked for others.

I would like to suggest a cheaper easier solution but I don't have the CNC
machine to test it on so I cannot guarantee it will work for you.

First I am concerned with how you ran the wires to the three switches.
Schematics don't show such things. I would wire a twisted pair from the
control box to each of the three switches. In that case any noise linking
into one conductor would also link the paired one in almost exactly the same
way. The noise would therefore tend to cancel itself by the time it was
conducted back to the control box.

My second suggestion would be to add a 50 ohm 1 W resistor from the switched
line to ground before the 4.7kohm resistor. The effect would be to lower the
impedance to ground and dampen induced noise. It will pull an extra 100 mA
from the supply which I would expect could handle it.

More effective still would be to use a optocoupler like the 4n25.

By the way, the LED's are shown backwards in your schematic.

On October 20, 2003 03:59 pm, you wrote:
> Wow what a great response! I think I will try the easy stuff first
> so I will put a wee cap on the limit switch input to the breakout
> board err/res manager.
>
> My breakout board is home made. See the circuit here:
>
> http://www.e-zflight.com/files/ncnczy.jpg
>
> gecko faults and the limits trigger the same input to pc, but the
> gecko's are fine. External LED's indicate gecko status. There are
> actually 4 gecko's used, drawing shows two.
>
> Eric
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "balsaman_cnc"
>
> <balsaman_cnc@y...> wrote:
> > The electrical noise generated by my Porter cable Router is
> > triggering my limit switch circuit. The limits are high and go low
> > if there is a problem. They are all in series (NC). If I set the
> > speed on my router down 20% or so the problem goes away. I slid
>
> one
>
> > of those ferrite donuts over the limit switch cable with no
>
> effect.
>
> > Is there something else I can try? I used shielded cable on all
> > cabling EXCEPT the limit switches...do I need to replace all that
> > cable? Are there other options?
> >
> > Thanks for any help you can provide.
> >
> > Eric
>