I have some Philips drivers coming for a project and being impatient and unable to wait till they get here and I can experiment, I’ll go ahead and ask about how this stuff works.
The datasheet for my driver is spectacularly uninformative, but info from another unrelated driver that uses the same dimming standard has helped me a little bit. The way I understand it, the two DIM wires are a monitored voltage line, and a ground. The dimmer is just a variable resistor that dumps voltage to ground, and the driver senses the voltage present on the DIM+ line and adjusts output to suit. The dimmer is just an adjustable pulldown resistor. All these drivers have the same graph with a straight line between 1V or less = minimum output (normally between 5% and not quite zero), to 8V or more for 100%.
Now the simple question that’s too silly for them to even mention in the documents: WHAT’S THE RESISTANCE NEEDED TO COVER THAT RANGE FROM MIN TO MAX, without ending up with a pot that hits full output in the first 1/4 turn of the knob?
To clarify, if the chosen pot’s value is too low the driver won’t ever reach max output, and if it’s too high it will hit max output too soon and leave some amount of travel wasted. If that makes any sense.
EDIT: So I suppose that we just figure it out using Ohm’s Law based on the source current from that Philips data. Does 80K-ohm seem like a good number? (13v max output at 0.15mA from the datasheet)
You’re link is broken but I think you are describing a center-tap potentiometer. The total resistance depends on how much current you would like in total. It is connected in such a way that the total current is always the same, the knob just adjusts the percentage that goes through the load vs the percentage that is wasted.
Right click/save as works, it’s the stupid way Firefox refuses to copy URLs without modifying them plus Philips’ stupid way of using a URL with a space in it.
BTW, these drivers are on clearance at LEDSupply for $25.
No! It does not sound like a good number (it’d have to be a 100K, to make it go to full 100)! I was really hoping to find a pot, of the right value, with a built-in switch (since minimum dimming isn’t 0 output), and, if that wasn’t enough, I wanted the switch to be a push-push latching style so the line AC could be switched without having to change the dimmer setting. Am I being too picky? Apparently so, because even Digikey doesn’t stock such things. I has a sad.
I own several expensive commercial high powered LED fixtures that use 0-10V dimming drivers. While I havent tried using them with other pots, the 100K logarithmic types have worked flawlessly. I considered using a pot with integrated switch, but opted to stay with the standard wall switch since the light pulled 265W and safety was critical. I mounted the pot right next to the switch.
Operation: when the violet (0-10V+) and grey (0-10V-) wires are connected, the driver achieves full dimming. When the wires are not connected, the driver outputs max power.
I just tested a different light rated at 165W with a kilowatt meter and recorded some results.
0-10V+ and 0-10V- wires:
Connected = 20 watts
Open = 165 watts
Have you checked out any of the 0-10V light controllers available? The IR controller in my thread has been fun and can be had for around $20 on aliexpress.
I’ve found other 0-10V drivers that recommend everything from 5K to 50K pots, using just two legs. I’ll just experiment with them when they get here. I hope they will work with a 10K, but I bet I won’t be that lucky…
Hmm, my mistake. For some reason I was erring on ~1v instead of <1v. Duh.
Can you show some pots (in other values) with the correct push-push latching switch for AC use? Eg ones you like for your application other than the value?
If there isnt enough total resistance in the dimming circuit, the driver will not dim to its fullest potential. Its easy enough to bench test your solution with a watt meter to find out how effective it is.
Ive only used 100K logarithmic because its pretty standard and will always work in external mounts (at least from what Ive read in other lighting threads). I spoke with a Phillips lighting engineer last year and they recommended that I add the resistance of the dimming wire (about a 50 feet run) to the total value of resistance to calculate which pot I should use. I dont have the total resistance spec any more… sorry. My drivers reach max output at around 1/2 the available turn travel in the 100K pot, so a 50K or 75K might work. IMO, there is plenty of adjustment and sensitivity in the 100K pot to attain the desired amount of lighting, so its not worth my time to try a 50K or 75K pot. The most important thing is to use a logarithmic pot. Posts are cheap on ebay.
Based on FP’s post, this is wrong isn’t it? FP:“If there isnt enough total resistance in the dimming circuit, the driver will not dim to its fullest potential.” That would mean the driver is sensing the return voltage on the DIM- wire, instead of just sinking the DIM+ voltage to ground, yeah? Doesn’t make a huge difference in actual operation, just means the pot direction might be backwards, but just for fun I wanna understand how it’s working.
I’m not sure that part of FP’s post is correct, unless I’m misunderstanding things. Let’s recap:
To me these comments clearly seem to be in conflict with one another.
My understanding is that the driver is a current source. Comfychair’s driver provides 150uA according to the datasheet. If we have a constant-current source we can reduce the output voltage by shorting it, or increase the output voltage by leaving the circuit open. In between it’s a matter of resistance: the lower the resistance, the closer to 0v we get… the higher the resistance, the closer we get to the “maximum” voltage.
Yanking the dimmer out of the wall and tearing off the wires gives the highest resistance, and thus full output.
It’s simple. We have a current source with 150uA. We want to see >8v across the terminals, so we put a resistor in between. We’ll use an equation from from ohm’s law to determine what value we need. Let’s say we want to hit 10v to “be sure”, although I’d recommend going much lower (8v or maybe 8.5v seems like a good number).
10v / 0.00015a = 66,666.66666 ohms
It’s as simple as that. While the source is CC/CV w/ a max of around 13v according to the datasheet, this doesn’t concern us at all. We do not need to subtract voltages or anything like that. We just need to use the equation above. I didn’t realize this until I went and looked at the datasheet for FP’s driver. They don’t post the voltage limit on the dim pins because it doesn’t matter.
Based on that math 50k might not quite get full brightness.
That looks like a great buy for great specs. You should double check the data sheets and part numbers but it looks like the 100K version is available in the US. Maybe the 75K is as well, but I didnt look that far.
Abacus also shows stock. Call the 800 number and plead for a small qty order and they might help you.
You a fool? NEVER!! I dont have the driver comfychair listed but I do have a pair of the the larger 150W Xitanium versions powering a large highbay. While an unscientific approach, I have noted that they all (5 or 6 different certified OEM’s of 1-10V dimming drivers) seem to reach max at about 1/2 way through the turning travel of a 100K pot. Sadly, I dont have a light that I can easily take apart to measure resistance of the pot where it allows 100% max output. Even if a 50K pot limited the full dimming capability, this might be advantageous in certain builds. I agree that 75K might be the best choice for these drivers.
I dont have the driver comfychair listed but I do have a pair of the the larger 150W Xitanium versions powering a large highbay. While an unscientific approach, I have noted that they all (5 or 6 different certified OEM’s of 1-10V dimming drivers) seem to reach max at about 1/2 way through the turning travel of a 100K pot. Sadly, I dont have a light that I can easily take apart to measure resistance of the pot where it allows 100% max output. Even if a 50K pot limited the full dimming capability, this might be advantageous in certain builds. I agree that 75K might be the best choice for these drivers.