Reducing a 0-10v dimmer control signal to 0-5v

Discussion in 'The Projects Forum' started by LandonL, Oct 31, 2010.

  1. LandonL

    Thread Starter New Member

    Oct 31, 2010
    1
    0
    I am using two buckpuck drivers to control an LED array. One channel is white, the other blue. I use the 3021-D-I-1000 model. The datasheet can be found here.

    http://www.luxdrive.com/download/?dltf&dmid=1109

    The controller is a RKM-ALC made by digital aquatics that provides two 0-10v dimmer control signals, at 34ma.

    So lets just focus on one channel, since what works for one, will work for the other.

    How can I effectively halve this signal to work on a 0-5v control circuit?

    Someone mentioned using 1k ohm resistors, and since the control pin impedance is 1k ohm, I would only need one, but when I try this it does not work. It also does not work with one placed on each line.

    I need a detailed explanation as I have not had any experience with circuit design in over 10 years. I am getting really frustrated with this project at this point.

    Landon
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    The buckpuck has a "Control" line to turn the LEDs on and off for PWM.

    Would need the information for the board that controls the buck converters (RKM-ALC) to answer (understand?) your question.

    What is the supply to the buckpucks?
    Where is 0-5V needed? (the control signal can be 0-10V from datasheet)

    To use a 0-10V signal as a 0-5V signal, use a voltage divider of two same sized resistors.
     
  3. iONic

    AAC Fanatic!

    Nov 16, 2007
    1,420
    68
    The Ref pin is set at 5V. Tiying this to the Control pin via a 5K Pot would be a straight forward Dimming option. (Fig. 9) Internal Dimming. An external Dimming source voltage is also shown in (fig. 10) and references 5V. In fact all figures refference 5V for the dimming control.

    The Absolute maximum rating for the Control Pin is 10V and thus the Controller should work, but is at the limit.

    I would think that a simple voltage devider setup should keep the voltage under 10V. a pair of 1K resistors in series and tap off the center and Gnd for aproximately 5V.

    Still don't know how his controller is meant to work, manually or automatocally...

    UPDATE:
    It appears that this is an automated Aquatic tank light controller which can be programmed to go on and off at User defined times and at different light intensities, also for multiple LED light colors.

    From a post at the following site it appears that programming 1V is equal to setting the LED light level at 10%, setting it at 10V is equal to 100% light intensity (atleast for the light arrays provided with the device). Yet despite what the Buckpuck datasheet says about a max control voltage of 10V, every instance they refer to uses a differential of 0V-5V.
    http://www.reefcentral.com/forums/showthread.php?t=1829802


    Perhaps programming the controller to 5V at a given time will produce 100% LED intensity when configured with the BuckPuck. In this case programming the controller in 0.5V increments might give you the same resolution (0% - 100% in 10% increments). In other words 0.5V for the controller = 10% of max LED brightness.

    I have seen another High Intensity LED setup with the buckpuck that used the ATTiny programable chip to send PWM signals of +5V at two different frequencies to drive the LED's at different intensities.

    I think we would all benifit from voltage measurments comming from the I/O's and Outputs of the Controller under normal operation with the basic LED's.



    RKM-ALC Features

    Multiple Ports
    Serial I/O, 2 x 0-10VDC, 2 x Pod Ports

    Serial I/O Port
    This port is designed to interface with the Aqua Illumiation LED lighting array.

    2 x 0-10VDC Ports
    These ports will allow advanced control of dimmable T5 ballasts.

    2 x Pod Ports
    These ports give the ability to add an additional two Lunar Pods to as system.

    Adapter Kit
    The ALC now includes the switch adapter kit. Which is a 6' cable that you can cut to length to get two individual cables to wire up dimmable ballasts or the Aqua Illuminations LED arrays.



    Tech Specs(RKM-ALC)
    ■AquaIlluminations Control: Six Fixtures Max per ALC

    Connections
    ■Serial In Port
    ■Serial Out Port
    ■Two 0-10VDC Ports
    ■Two Lunar Pod Ports

    Physical Details
    ■Dimensions: 1.0" x 2.25" x 4.30"

    Package Contents
    ■One ALC Module
    ■One 3' Bus Cable
    ■One Switch Adapter Kit
    ■Two Mounting Srews
     
    Last edited: Nov 1, 2010
  4. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    I assume you have connected up the circuit like the following.

    When it does not work, have you measured the voltage at the follow two points with different desired dimness setting say 30%, 50% 70% and 100%?

    This would tell you why it didn't work and what else need to be done to make it work.

    [​IMG]
     
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