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  1. #1
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    making a 24 vac potentiometer

    http://www.kele.com/panel-fabrication/spa.aspx

    would anyone know how to make these with radio shack parts? would like to make a couple on the cheap for testing , stan
    Keep it simple to keep it cool!

  2. #2
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    There is little outside of drilling a hole in a cover plate and a label. I think kele might have screw terminals on them for easy wiring, which you will not easily find elsewhere.

    Jameco, mouser, digikey will have them all day long and the fancy knobs to go with them. Just search for "10k pot".

    http://www.jameco.com/webapp/wcs/sto...type=jamecoall
    http://www.jameco.com/webapp/wcs/sto...type=jamecoall

    Pots are rated by power. Not sure what your thinking about doing with a pot and 24v but keep in mind, exceed the power rating and they smell pretty nasty.
    Propagating the formula. http://www.noagendashow.com/

  3. #3
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    hi yes , thats what I want to be careful with , or spiking an AI with too much current, maybe better to spend a bit more and play it safe?

    here is a cheaper one https://www.ecproducts.co.uk/product...tem=1&pid=2400
    Keep it simple to keep it cool!

  4. #4
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    Sep 2002
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    Hampton Roads, Virginia
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    To test 0-10v and 4-20mA Analog inputs you are better using one of these http://www.kele.com/tools-and-test-equipment/asg.aspx The true trade price is nothing like the "Internet price" shown, your cost will depend on your companies discount. The 10K pots are good for thermistor inputs.

    Kevin
    The first rule of any technology used in a business is that automation applied to an efficient operation will magnify the efficiency. The second is that automation applied to an inefficient operation will magnify the inefficiency. - Bill Gates

  5. #5
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    I have something like this on the way the software Im using has simulator,which is good for checking program and response , but Im in process of of setting up a little live network at home ,Innotech kit, and I think a couple of these on the wall will work brilliantly
    I may just pay out for the ECproducts ones stan
    Keep it simple to keep it cool!

  6. #6
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    Just about any pot will work for simulating 0-10v from 24vdc for less than $10.


    You want to add a pair of resistors to the setup and not just use the pot and 24v. Without you will be feeding 0-24v into that input, might be fine...might not. With a pair of resistors, form a voltage divider to cap the max voltage at 10v then slip the wiper and one end of the pot in series with the resistor tied to ground.
    Propagating the formula. http://www.noagendashow.com/

  7. Likes stanbyyourword, word66 liked this post.
  8. #7
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    Nix my wiring above, its wrong. Same few parts will get the job done. Next time I'm working with schematics and I think about it Ill post a drawing.
    Propagating the formula. http://www.noagendashow.com/

  9. #8
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    great
    Keep it simple to keep it cool!

  10. #9
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    Jan 2015
    Location
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    Good suggestion about making a potential divider in order not to draw too much current. Another tip when designing something like this is to make sure that the current through the pot branch is a good deal higher than the current draw of the input to the circuit sensing the pot setting voltage. Typically 10x current through the pot branch would be a good starting point. This will also help you calculate sensible values of for the pot and the bias resistors

  11. #10
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    Using a Diode, you will cut the 24VAC to 12VDC, unless it is 24VDC already.
    Knowledge is money - Ignorance is expensive!!

  12. #11
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    I went with the ecproducts ones , played it safe got 1 0-10v and 1 11kohm resistor stan
    Keep it simple to keep it cool!

  13. #12
    Join Date
    Oct 2010
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    Use a standard Johnson 350p control , and in place of it sensor use a 500 ohm (I believe) resister. It will deliver 0-10 vdc
    Or 4-20ma

  14. #13
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    Feb 2004
    Location
    New Mexico
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    If you want to have some fun, Radio Shack carries ( or used to) a book on building power supplies.
    I built one years ago. It's a variable power supply that uses a 24vac transformer, a full wave bridge rectifier and a LM317 regulator. I did some customizing so I could select output 0-5, 2-10, 4-20ma and 24vac. I can't remember where the base schematic came from but the one in the RS book might get you where you want.
    You really want a clean output and that will need some filtering.

    The book is called Building Power Supplies Cat # 276-5025.

    Another idea is if you have access to a used controller where you can program the channel output like an old Automatrix GX. Then just punch in the numbers.
    I should have played the g'tar on the MTV. MK

    You can be anything you want......As long as you don't suck at it.

    SMW Lu49

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