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Variable voltage dropper for speed control of tattoo machine

Discussion in 'General Electronics Discussion' started by Kastrosama, Sep 8, 2014.

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  1. Kastrosama

    Kastrosama

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    Sep 8, 2014
    Howdy, im looking to reduce 9v using a 1k pot so its variable, just wondering if theres anything else thats needed.
    Its to make a powerpack for a rotary tattoo machine.

    In my head, its literally a 9v batt, positive onto the pot, negative to the negative lug on a mono chassis mount jack.
    from the pot to the positive lug on the jack..
    I may add a switch..

    But yeah.. its literally that simple?
     
  2. Gryd3

    Gryd3

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    Jun 25, 2014
    Almost, but not quite...
    Many potentiometers can't handle much current, so directly driving a motor is sometimes out of the question. If the motor is small enough, you can get away with it.
    If this is a final design choice, you may find that you need to swap out the potentiometer as it wears, or that the potentiometer just won't cut it.
    There are other more robust choices, but this is up to you to decide if that's how you want it.

    Edit: I should mention that the speed control may be sloppy and inconsistent...
     
  3. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    Hello
    So its to slow down the tatoo motor I guess? This will work but its worth knowing how much current the unit draws. Otherwise it could damage the POT if you choose one thats too lower power rating. A better option is to use a variable current or voltage source that you could vary using your POT. This way you can use a smaller POT and let the rest of the circuit do the work. Varying the current will vary the voltage and varying the voltage will vary the current.
    Adam
     
  4. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    You beat me Jerid, dont you sleep? :)
     
  5. Kastrosama

    Kastrosama

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    Sep 8, 2014
    this just melted my brain hahah
    so yeah, im not the most tech advanced.

    So would a more robust pot work or would it come down to the pot value?
     
  6. Gryd3

    Gryd3

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    Jun 25, 2014
    Surprisingly, yes, but not enough ;)


    Yes and No :p can't give you a really easy answer.
    You will need a potentiometer with a higher wattage rating to directly handle your motor. The Ohm rating on it will translate into the slowest you can turn your motor down. Any potentiometer will allow you to turn it to full blast.
    I can't give you example wattage though. If you have access to some cheaper parts, try them out. The worst that will happen is smoke will escape from the potentiometer, this will tell you to increase the Watts the potentiometer is rated for. If a little flame flickers... you should come back and let us know, we will help to get you an adjustable power supply to feed to motor.

    Edit: I beat you again Adam \/
     
  7. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    Hi
    Yes if you want to call it more robust, thats a good name. We need to know the spec of the motor which will decide the value and power rating of the POT.
    Adam
     
  8. Gryd3

    Gryd3

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    Jun 25, 2014
    Do you or a friend have a multi-meter?

    What would really help would be markings of the motor, or hook it up to a battery and tell us how many Amps or milliAmps it is drawing. (If it's in the Amp range, you're out of luck)
     
  9. davenn

    davenn Moderator

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    Sep 5, 2009

    no, its being suggested to you that an adjustable voltage regulator IC would be the best way to go
    that will stop any chance of a pot burning out.
    please answer what was asked a few posts ago ... What is the current required by the motor
    It will probably be labelled on the motor
    xxx Volts
    xxx Amps


    cheers
    Dave
     
  10. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    LoL. You will run out of answers soon I am sure :)
     
  11. Gryd3

    Gryd3

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    Jun 25, 2014
    A constant current or voltage device will do what you asking a potentiometer to do, but with very nice extra features.
    They only need a potentiometer to set them, and this potentiometer can be very little if you want it to be and can be tucked nicely in the pen out of the way.
    They compensate... Say you have it set at 6V, as the battery dies, or if the motor gets bogged down, the voltage will stay exactly where you set it at 6V.

    This is an ideal solution for you, but requires a couple extra parts.
    We'll wait to find out what motor you want to drive and we can draw up a quick circuit, or give you a little pros/cons list over using a potentiometer if it's a viable option with your motor.
     
  12. Kastrosama

    Kastrosama

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    Sep 8, 2014
    The motor is housed inside the workings of the tattoo machine..
    They are handmade Uncle Roys Rotarys.. and his secret is the motor.. he has them custom made..
    I doubt he will give me the details.
    you can get an idea of them from here : https://www.facebook.com/roy.richardson.165/photos_all

    Before I posted here, i bought the following..
    http://www.ebay.com/itm/181378857201

    If they dont work, its no loss.. i often circuit bend toys etc so i can use them for something else..

    So once the Pot can handle the wattage of a motor, i.e. has a larger rating. then in theory it should be able to reduce the voltage of the battery, reducing the power to the motor?

    I have a variable power supply that I can use, but i want to use this in places where there is no power supply.. i.e in a camper or at an outdoor tattoo festival.
     
  13. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    Ok tell us what power supply they use for them that will help us. There are more than two ways to skin a a cat.
    Adam
     
    Gryd3 likes this.
  14. Kastrosama

    Kastrosama

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    Sep 8, 2014
    with a rotary the voltage varies.. much like any tattoo machine.
    some people use them at different voltages depending on the setup of the tension etc on the tattoo machine.

    heres my power supply.
    http://www.skincandy.net/power-supply-1001-17/
     
  15. Gryd3

    Gryd3

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    Jun 25, 2014
    yes, just remember that the 10K or 1K rating is for Ω and is not in anyway related to it's power handling capabilities.
    How a potentiometer or any other resistor will work in this situation is by forcing the electricity to pass through the resistor. This does not lower the voltage of the battery, this simply splits up the battery voltage. So if you want to use a 9V battery, and you want 6V at your motor, then the resistor or potentiometer will have the 3V that are left over. This voltage does not magically disappear though... there are no moving parts or lights, so a resistor or a potentiometer will get rid of this extra voltage as heat. It's not just voltage that causes this to heat up though, its also how much current your motor draws, because any current through the motor also goes through the resistor/potentiometer because it is in-line with it.
    If you potentiometer seems to work, give it a test with some ink and some leather/pork to see if the potentiometer keeps workin' well when the motor is doing some work.
     
  16. Gryd3

    Gryd3

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    Jun 25, 2014
    ...Hrm, this does not help as much as I hoped.

    0-22V supply, and it seems like a typo that it can provide up to 18A? That seems way too high for a small motor like that...
    What does the display show when you use it?
    What do you commonly have the voltage set at? (You would not set your current, but I'm hoping it would show it.)
     
  17. Kastrosama

    Kastrosama

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    Sep 8, 2014
    The power pack is in the studio, so ill have to check when im in and ill get back to you here.
    Not sure if its a typo, the power pac k is universal, to be used with all sorts of tattoo machines..
    but I run my liner machine (coil machines) hard and fast at 10volts, my shader machine (also coils) at about 6.5v
    Coil machines work like a glorified doorbell :)

    Cheers for the info regarding how the potentiometer works.. it makes perfect sense!

    Ill message Roy to see what info I can get from him about his motors.. what is it im really looking for? current or?
     
  18. Gryd3

    Gryd3

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    Jun 25, 2014
    Well. You run your guns at 10 and 6.5V, so ideally if you can get him to tell you the current draw.
    We are looking for 'peak' and 'continuous' draw of how many milliAmps or Amps is required.
    The current draw will vary with the voltage supplied, so hopefully he has a small chart. If not, if you have a buddy with a multi-meter, you can measure it yourself.

    This will also help us determine how long a 9V battery will last. (Continuous draw is most important)
     
  19. Kastrosama

    Kastrosama

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    Sep 8, 2014
    Ill grab a multimeter tomorrow, how does one go about measuring? It will probably be easier than asking Roy, but ive messaged him, so the ball is in his court..

    Ive been describing 2 different styles of machines in previous posts.. coil and the rotary, its the rotary that has the motor im looking to build my powerpack for..
    I use about 4.5v for my rotary machine to do dotwork.
     
  20. Kastrosama

    Kastrosama

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    Sep 8, 2014
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