0-10VDC Sinking Voltage output

Discussion in 'The Projects Forum' started by ben859420, Aug 21, 2017.

  1. ben859420

    Thread Starter New Member

    Jul 19, 2017
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    I understand that most LED lighting inverters which allow for a 0-10VDC signal input to control the brightness require a voltage signal that can "sink" as opposed to a sourcing 0-10VDC output that most building controls provide.

    I need to covert a 0-10VDC sourcing output to a 0-10VDC sinking output in order to control these lights.

    I have not seen anyone put together a circuit to do this conversion. At a glance it seems rather simple however in practice I keep having a lot off issues implementing a working circuit. The Dimming input seems to sink about 0.1mA of current however as the voltage changes so does the current required.
    The basic circuit I have put together involves an opamp to a PNP Transistor a separate 12VDC power supply is powering the opamp.

    2017-08-21_16-44-41.jpg

    I beleive that the PNP may be getting damaged in some cases if a light is not connected.

    I perfer not to do PWM.

    Appreciate the help.
     
  2. dendad

    Well-Known Member

    Feb 20, 2016
    1,962
    510
    Why not just use the OpAmp output? There is no need for the transistor. It is a low current application and the OpAmp can drive that ok.
    And they can source and sink current (unless an Open Collector one is used).
    What are you trying to drive the LED controller with? If you just want to control the LEDs, just put a pot on the input running from 10V supply.
    A bit more info would be a help.

    I found this site...
    http://pospert.org/led-driver-wirin...dimmer-circuit-diagram-0-10v-or-wireless-jpg/
    It has a circuit of a controller. And it looks like a variable resistor between the 0-10V+ and 0-10V- is all you need.

    maybe you could use an opto isolator to drive it so whatever (Arduino???) you are using to drive it can be isolated.
     
    Last edited: Aug 21, 2017
  3. ben859420

    Thread Starter New Member

    Jul 19, 2017
    3
    0
    I have a PLC type controller that will be changing the light level. The PLC controller only has the sourcing type 0-10VDC output which doesn't work with this type of input. I need to run about 60 of these lights all off the same 0-10VDC signal. When you change the voltage output to the lights the current can spike a little up to 3-4 milliamps. if you multiply it out your looking at a few hundred milliamps over a 10v voltage drop so the total power dissipation would not suit an op-amp alone. I could also possibly buy a converter however I am unable to find anything at a reasonable price.

    A variable resistor would work however I would be unable to control it via the PLC.
     
  4. dendad

    Well-Known Member

    Feb 20, 2016
    1,962
    510
    How about something like this?
    The dual Opto is used so you can get feedback to linearise the 0-10V to the LED controller.
    As to resistor values, that would be up to experiment.
    0-10V LED interface.jpg

    Another option would be to use an ESP8266 at each light and do it over WiFi.
     
  5. ben859420

    Thread Starter New Member

    Jul 19, 2017
    3
    0
    I'm not sure I understand how the opto is able to control the 0-10VDC output. Isn't an opto going to be either on or off?
     
  6. dendad

    Well-Known Member

    Feb 20, 2016
    1,962
    510
    The opto can run in a linear mode. It all depends on the LED current. That is why there are 2 Optus. The current through the LEDs. Are the same and the output of the second one is used as feedback to the OpAmp, and if the resistors are selected well, it will be sort of matching. The local opto output will be 0-10V as will the remote opto. This is just an idea and will work in a fashion that may well be good enough for the job. Years ago I did something like this but I can't remember what it was for.
    Optos with FETs can be used but they are not so common. Also, a couple of LEDs and light dependant resistors could be used. The matched pair of them allows feedback to approximate sensing of the 0-10V.
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    15,869
    4,645
    One device is the IL300 linear opto.
    Max.
     
  8. ebeowulf17

    Well-Known Member

    Aug 12, 2014
    2,330
    409
    It seems like you could also use your existing circuit design, or maybe the MOSFET equivalent (my gut feeling is that it would be better, but off hand I couldn't say why that would be,) and just use a very high value resistor (1Meg?) across the base and emitter to prevent transistor damage in the case of disconnected light controllers.

    Don't take my word for any of that. I'm a rookie, just brainstorming and thinking out loud.
     
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