How would I make one of these?

Discussion in 'The Projects Forum' started by ramos96, May 12, 2013.

  1. ramos96

    Thread Starter New Member

    May 12, 2013
    2
    0
    Hi all,

    I recently was lucky enough to get a Blacktooth laser cutter/engraver, the laser output strength is controlled via a potentiometer that outputs 0-5 volts, I would like to swap out the pot to a digital type control where I can set the output more accurately and also display it, what is the best way I can accomplish this.

    Humbly,
    Roo
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,058
    3,820
    Pots cannot control huge amounts of power and 0 - 5 volts sound like a digital control to me.

    How accurate is "accurate". Sometimes, the design is plenty good enough based on other errors present in the systems that better control cannot overcome anyhow - so why try.


    Something as simple as air flow in the room, ambient temperature or distance to edge of work-piece overwhelm any additional control "accuracy". Having extra digits to the right of a decimal point make people feel good but many times they are "insignificant" digits (pun intended).
     
  3. colepinter

    New Member

    Apr 19, 2013
    11
    0
  4. WBahn

    Moderator

    Mar 31, 2012
    17,748
    4,796
    It sounds like your pot is generating a control or reference signal and, if that's the case, it is much easier to do what you want. You can purchase digital potentiometers, but they may not give you the resolution you are looking for. You can also replace the pot with a DAC and a microcontroller.
     
  5. ramos96

    Thread Starter New Member

    May 12, 2013
    2
    0
    That is what I am thinking also to just use a micro controller, I wondering if I can just do it with an arduino and using PWM, from what I have been reading so far today that seems to be what I am trying to accomplish. I am really new at electronics I have lots of ideas but I don't have the vocabulary yet to get it across. I am thinking a tenth of volt should be enough resolution.

    Humbly,
    Roo
     
  6. colepinter

    New Member

    Apr 19, 2013
    11
    0
    well, a good example would be the atari punk console synthesizer, using two 1meg ohms one for each oscillator, and it running off a 9V battery, those two 1meg pots are voltage controllers, and thats 9 volts... 5 volts is nothing for a 1 meg ohm potentiometer i would suppose, and you can get them cheap.
     
  7. colepinter

    New Member

    Apr 19, 2013
    11
    0
    OH, im sorry that ive read the post wrong.
    hes wanting a digital controller, what i would personally do is use a digital power supply made for tattooing, you can get them cheap online
    http://www.ebay.com/itm/Iron-LCD-Di...690?pt=LH_DefaultDomain_0&hash=item56562f349a

    there is a good example, pemenantly short out one of the 1/4 jacks (thats the foot switch pedal) or you can even use that well engraving like a tattoo machine, hit the pedal when you want the machine to work, and the other output if the polarity matters, youd have to just find out which is ground and which is positive
    i have converted one of these into a scientific power supply that works great. 1.5v all the way up to 15v.
     
  8. WBahn

    Moderator

    Mar 31, 2012
    17,748
    4,796
    I would be hesitant to use a PWM unless you filter the bejesus out of it. You don't know how the system is sampling that signal.
     
  9. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    How about replacing the 270°-rotation pot with a 10-turn pot and a mechanical counter dial.

    Ken
     
  10. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    Or with two pots, one for coarse and one for fine adjustment?
     
  11. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    Not easy to accurately return to the same setting that way...unless the OP would set the course pot once and then just use the fine one.

    Ken
     
  12. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    Along with a display/dvm that measures the output voltage it will be possible to get to any point he wants.
     
Loading...