0-10 volts is not 0-10

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Ponchik

Ponchik

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Electronologist
I measured the output of a 0-10V LED dimmer and on high setting it is 35.7 Vdc and on the lowest dim setting it is 33.4 Vdc. The LED strips dime fine. But my question is why is it 0-35 and not to 10?

I could not find the internal wiring diagram of the dimmer. I can find the external wiring diagram but I like to see what the diagram look slike internal to the dimmer.

Thanks
 
with connected load.

Now I need to go check without a load. BRB.
 
Without a load the voltage is about 50V regardless where the dimmer position is.
 
That’s strange, I have seen the open dim loop circuit as high as 20 VDC, I built a loop tester using D batteries and a potentiometer for test 40-50 fixtures at a time, depending on the driver program, usually about 3 VDC would take them to full dim. Are your meter batteries good?
 
edward said:
Without a load the voltage is about 50V regardless where the dimmer position is.
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If the dimmer is a two-wire model with no neutral connection it will not be able to power its internal electronics when there is no load, so the control terminal voltage with no load will vary depending on the internal circuit design.
 
I am using Fluke DMM, I installed new battery. With new battery, I measure a bit lower DC voltage but it is still mid 30s. I measure across the +/- of the output of the driver.

The dimmer switch has (4) wires, 120V power in and power out and two DC wires purple and gray.

I get constant 120V at the input of the driver regardless where the dimmer is.

I was always under the impression that the output of the driver is lower DC and the dimmer is dimming the DC side hence the name "0-10V dimming". Maybe I don't quit understand the 0-10V dimming.
 
0-10v is the control voltage, which corresponds to 0-100% output, and with LEDs measuring open-circuit output voltage is meaningless. If the dimmer device has only 4 wires (120v in, LED out), it's not a 0-10v controlled dimmer (which would have two additional wires/terminals for that). Post a picture or the model of the dimmer and we can confirm that.
 
zbang said:
0-10v is the control voltage, which corresponds to 0-100% output, and with LEDs measuring open-circuit output voltage is meaningless. If the dimmer device has only 4 wires (120v in, LED out), it's not a 0-10v controlled dimmer (which would have two additional wires/terminals for that). Post a picture or the model of the dimmer and we can confirm that.
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Screen Shot 2021-10-23 at 9.40.36 AM.pngScreen Shot 2021-10-23 at 9.39.49 AM.png
 
The driver provides a 10V source with an equivalent series resistance. The dimmer provides a variable loading to this 10V source to pull down the voltage across the violet and gray wires, such that the voltage can be varied between 0V and 10V.

When you are measuring the voltage across the violet and gray wires, are both of these wires still connected between the dimmer and driver? Measuring the voltage across just the dimmer violet and gray wires is relatively meaningless because it is the output terminal of an active pull-down device. But you should see 10V across the violet and gray wires from the drivers when they are not connected to the dimmer. Just remember that the driver is the sourcing the power for the 0-10V signal, and the dimmer is applying the appropriate load current necessary to obtain a desired signal voltage that's somewhere between 0V and 10V (that's why it says "Sink" on your spec sheet above).
 
Here is what I have and where I measure the DC voltage of about 35V dc.2021-10-2313.23.194650503095482620904.jpg
 
The voltage required between the red and white wires is determined by the manufacturer of the driver and the LED lights that it connects to. The required voltage depends on the number of Light Emitting Diodes (LEDs) in series within those LED strips, and it is established by the manufacturer.
The 0-10V dimming control signal is the voltage across the purple and grey wires. 10V will provide a full light level ouput, and 1V or less will be fully dimmed (but not necessarily completely off).
 
I'm confused. First you said you were measuring the output of the 0-10 of the dimmer. Now you state you are measuring the driver output.

The 0-10 is only for the control of the driver. It is not the output voltage of the driver. Is the driver you are testing a constant voltage or constant current driver? Big difference.
 
curt swartz said:
I'm confused. First you said you were measuring the output of the 0-10 of the dimmer. Now you state you are measuring the driver output.

The 0-10 is only for the control of the driver. It is not the output voltage of the driver. Is the driver you are testing a constant voltage or constant current driver? Big difference.
Click to expand...

This was where I did not fully understand 0-10V dimming. I was under the impression that 0-10V meant the output from the driver to the LED strips.
 
Thank you all for your replies. I understand how it works and why I am getting the DC readings
 
zbang said:
0-10v is the control voltage, which corresponds to 0-100% output, and with LEDs measuring open-circuit output voltage is meaningless. If the dimmer device has only 4 wires (120v in, LED out), it's not a 0-10v controlled dimmer (which would have two additional wires/terminals for that). Post a picture or the model of the dimmer and we can confirm that.
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Right. It's an analog signal.

Sent from my BE2028 using Tapatalk
 
LED brightness is current controlled. The voltage across a string of LEDs depends on the number of LEDs in series. Dimming is done by either varying the current in the string, by PWM'ing the current, or a combination of both.

/mike
 
n1ist said:
LED brightness is current controlled. The voltage across a string of LEDs depends on the number of LEDs in series. Dimming is done by either varying the current in the string, by PWM'ing the current, or a combination of both.

/mike
Click to expand...
What is PWM'ing the current or combination?
 
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