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Author Topic: AC dimmer via Mach3  (Read 2295 times)

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Offline Lubby

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AC dimmer via Mach3
« on: March 09, 2015, 10:09:00 PM »
I'm adapting my CNC for an art project - a video camera moving through a model set.  It leads to yet another technical issue.  I need to work out a way to create a dimmer for some lights, or control AC current.  I think there's likely various ways to do this. I'd appreciate any feedback some of you might have.

A simple on/off would be quite easy through an output relay.  The thing is that I want to be able to dim the light or control the intensity of it.
I could think of two possibilities:

1. With the machine as it currently is I'm no longer using a spindle. I'm wondering if I could use the VFD of the spindle to control a circuit board.  This way I could simply include the intensity of the light within the G code ( or S Code) by increasing or decreasing the 'speed' of the spindle.  Could this work?  Any suggestions on a board that could work with this or what type of hardware would be needed?

2. Another consideration was to configure things for a servo spindle.  I haven't done this before but I believe I can control the PWM rate this way.  I could use the PWM to run a circuit board and control the lights.

I suppose a third option would be to use LEDs which are a bit easier to control digitally but it would still require some sort of VFD or PWM control I'd think... Unless I could use a stepper signal sent to an arduino which would then run a circuit board.  This way I could just run the light's intensity like I would an axis using steps.

I'm sure this is outside the typical spectrum but I appreciate any feedback and hope this it might be informative to others in regards to the possibilities available in interfacing between Mach and the physical world.

Thanks

Offline Tweakie.CNC

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Re: AC dimmer via Mach3
« Reply #1 on: March 10, 2015, 03:27:13 AM »
Check out  SSR's (Solid State Relays) - many types are 'opto-isolated', require less than 10mA drive current and can be driven directly from the Mach3 PWM signal (spindle control) and will switch a/c mains voltages proportionally with the PWM waveform. As they switch at the 'zero crossing point' of the mains a/c there is little or no EMI noise produced by their operation and this may offer a solution.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Lubby

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Re: AC dimmer via Mach3
« Reply #2 on: March 10, 2015, 08:58:31 AM »
Thanks Tweakie.

I did do a test with an SSR and PWM fade running off an Arduino.  There's problems with the AC wave and the digital pulse.  It fades but it's quite choppy.  I think this could likely be solved through a circuit board of some type.  I'm just not sure which.

But good to know I might be able to do this through the PWM spindle control.
Re: AC dimmer via Mach3
« Reply #3 on: March 10, 2015, 09:25:55 AM »
Possibly a small motorized aperture ... or filter element ? Infinitely variable by motor position ?

Russ
Re: AC dimmer via Mach3
« Reply #4 on: March 10, 2015, 10:53:06 AM »
... at the light source of course, not at the camera. The filters could be colored to give additional effects.

Offline Lubby

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Re: AC dimmer via Mach3
« Reply #5 on: March 10, 2015, 11:01:27 AM »
I found a PWM AC dimmer circuit board online ( https://www.tindie.com/products/thewp122/ac-60hz50hz-phase-controller-dimmer-board-arduino-compatible-2/ ) and I'll use the PWM spindle control to operate it.

Thanks for the feedback.

Offline BR549

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Re: AC dimmer via Mach3
« Reply #6 on: March 10, 2015, 12:22:59 PM »
Hook a SMALL stepper to a stock dimmer switch. Use an axis to control.

Easy Peasy, (;-) TP
Re: AC dimmer via Mach3
« Reply #7 on: March 10, 2015, 02:57:11 PM »
Hook a SMALL stepper to a stock dimmer switch. Use an axis to control.
Now THAT'S my kind of thinking right there, I luv it!
Milton from Tennessee ya'll.

Offline Lubby

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Re: AC dimmer via Mach3
« Reply #8 on: March 11, 2015, 09:43:10 AM »
Hook a SMALL stepper to a stock dimmer switch. Use an axis to control.

Easy Peasy, (;-) TP
  Hear, hear!  What a great idea.  It's like an extra set of hands.  Nice one.