Convert Sourcing 0-10v to 0-10v Sinking

Manufacturer, model number of the lighting controller?

Manufacturer, model number of the lighting fixtures?

Is the voltage/current AC or DC?

How much current are you sourcing or sinking?

Is the 0-10 volts strictly a control voltage and there is another bus that provides the power?

Do you have a schematic diagram of the lighting circuit that you can share with us?

I've been in the electrical engineering field for 31 years now and I've never seen a sourcing to sinking converter. The best I can come up with is a voltage to current converter which is basically a transconductance amplifier. But most of these are designed for relatively low currents in instrumentation circuits. You could certainly scale up the output for larger currents. Or you could find a DC electronic load with analog input.

http://www.chromausa.com/product/modular-dc-electronic-load-63600/

Just to clarify a bit.The lighting controller i'm using outputs a 0-10 vdc "control signal". The controller supplies the 0-10vdc from its own internal power supply,therefore it is a "sourcing output".

The LED fixtures we're using have 0-10vdc dimming incorperated into each driver. The driver supplies 24vdc across the control leads,which then has to be broken down to 0-10vdc by the dimmer controller,ie. the voltage has to be "sunk' down to 0-10v.This is done by varying the resistance across the control leads.(Most new LED fixtures use such a sinking type control). The control leads are all wired in parralel back to the dimming controller.

Fixtures are 120-277 vac.

Is there any way to use such a lighting controller to control these fixtures?

It will all depend on the design of your lighting controller. Since the fixtures will impose a 24 VDC voltage across the control lines, as long as your lighting controller can regulate voltage while sinking current, the answer would be yes. Without a schematic of the lighting controller, I have no way of saying for sure. A shunt type of regulator will typically sink or source currents while a series or pass regulator can (generally) only source current. If the lighting controller uses a switching topology, then it is only likely able to source current. There are some four quadrant switching topologies, but they are generally only used at higher power levels.

Here is a simple circuit that will do basically that. This is basically a shunt voltage follower. The input goes into the inverting input of the operational amplifier because Q1 acts as an inverter. A few cautions here:
1. You can't take it completely to zero volts. You are limited at the lower limit by the saturation voltage of the NPN transistor. Roughly about 0.2 volts but it depends upon the base and collector currents.
2. You may need a higher current transistor than a classic 2N2222 depending on how much current each driver is going to output as you pull the 24 VDC down to the 10 to 0 VDC range. Only you know what the 'sinking' current will be. Short the fixture driver control line to ground and measure with an ammeter. If you have sixty-six fixtures, that may be a lot of current.
3. You may need to change the value of R5 depending on the beta of the transistor and the supply voltage to your op amp. Make sure that the base to emitter current doesn't exceed the specified value in the transistor data sheet for the given resistance and op amp supply voltage. For a 2N2222, I would keep the base current at or below 15 mA.

Good luck with your quest.

This is how I would do it:

Use one transistor per lamp so you don't have to worry about current draw from the total circuit.

The emitter follower will convert the 0-10 volts drive into 0-10 volt sink.

You must like the smell of roasted BJT in the morning.

I like this.

My only criticism is that this assumes a common return between all three circuits. This is a reasonable assumption most of the time but we've all been burned by an unstated assumption.

So very true (common returns). The circuit was really just meant to illustrate the concept. We have so precious little information about the application, that it is impossible to provide a complete solution. There are no protections of any kind built into this, we don't know if a true zero volts is required (and hence a more complicated circuit to pull it all the way down to zero), we don't know the source impedance of the fixture drivers or the lighting control output, and . . . , and . . . ., and . . ..

Lighting controller 0-10volt output min. impedance=1200 ohms

One led driver control leads shorted together. current=20 milliamps

66 led drivers 0-10v control leads all shorted together: max control current=20 milliamps. Sounds crazy that control current doesn't increase from 1-66 fixtures, but I Flukemetered it.

This won't require true zero volts;1.0 volts would be low enough.

Returns could all be made common.

Sounds like you've got it made in the shade then. Sounds like you could do this with one PNP transistor in that case. You might need some series resistance in the base to limit base current. Or you could go with the op amp approach which provides a bit more isolation between the lighting controller and lighting fixtures.

What is device U1? Never seen that symbol before.

U1 is an unspecified operational amplifier.

I am assuming this is 66 circuits that you want to invert. What is the current draw on the LEDs? You might be able to use some NPN Darlington Transistor Array ICs (8 circuits each). They will sink 500 ma. on each circuit. If your load is greater than that, you can connect more than one circuit in parallel to increase current.

http://www.ti.com/lit/ds/symlink/uln2803a.pdf

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Del

I think Professor Norton and Professor Thevenin should be able to answer your question. They will also need to know the driver and receiver circuits that you have. Careful use of these two guiding principles in testing and analysis can tell you the equivalent circuits you actually have if the manufacturer of the circuits does not give you any support. After doing this work you might find that you only need to add one external load resistor to get this to work.

its been pretty common and has been discussed in a number of degrees here.

Something like this http://www.automationdirect.com/adc/Shopping/Catalog/Process_Control_-a-_Measurement/Signal_Conditioners/DC_Voltage,_Current_or_Potentiometer_Input/FC-33 ? You'd have to make sure it can sink the current you need. If that doesn't work out, Google something like 'voltage converter', 'power conditioner', or similar combinations.