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  1. #1
    Moderator ShipWreck's Avatar
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    Dimming moonlights

    Are there electronics guru's out there?

    I am slowly programming/building my custom controller and have always like the idea of having the moonlights do a lunar cycle. I have a controller that has a 4-20ma output and have a 24vDC power supply (could also have other power if req'd).

    I would like to be able to use the 4-20ma output to control the power of the moonlights (preferably LEDs array). Does anyone have schematics or the ability to draw schematics to do something like this? I can write the program no problem (that's my job) so I just need something that would respond.
    Rob
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  2. #2
    liv
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    Former Moderator liv's Avatar
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    this should do it: http://led.linear1.org/led.wiz

    i use this prog all the time
    works great!

  3. #3
    Moderator ShipWreck's Avatar
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    That is a very usefull tool for designing a standard on/off LED array. I am trying to us an analog signal to vary the output of the lights. Basically think of my project as an automatic dimmer switch controlled by a computer.
    Rob
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  4. #4
    liv
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    use the led calculator to get into the proper resistance... then i'd find a way to pass this current through a chip to cut the in-out to what you want.

  5. #5
    Moderator ShipWreck's Avatar
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    This is where I get stuck. I only have basic electronic knowledge so I can build the standard array but selecting chips and other more complicated circuits my design skills fall apart.

    I can solder anything just need to know what to where
    Rob
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  6. #6
    Senior Member Bonaqua's Avatar
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    If you're going to use that 4-20mA output to power the LED/array...tough.
    That's not enough.
    Typical LEDs use 30-50mA (per piece) to get decent light output.
    You have 20mA max available. (you could use maybe only one LED rated 15mA with high light output, if you find one)
    Unless you find a bunch of 20 LED rated 1mA each, you cannot do it this way.

    However...you can use that output to controll externaly powered LED-array.

  7. #7
    Moderator ShipWreck's Avatar
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    I guess I should explain a little, a 4-20mA analog output is not meant to power a device but to control. A digital output is like a lite switch and will turn the lights on or off. An Analog ouput is a variable output that can be used to control a device through a range, example controlling the speed of a motor. The analog signal is a the control signal into a circuit, but there is still a seperate power source to power the device being controlled.
    Rob
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    Upgrade in the works! Keep looking for an update.


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