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Topic: Figuring out how to control this LED driver (Read 238 times) previous topic - next topic

Jtroutt19

May 19, 2018, 09:32 pm Last Edit: May 19, 2018, 09:36 pm by Jtroutt19 Reason: Had to add pictures wouldnt allow me to on my phone.
Hoping to get some help here. So I am trying to control these drivers from an arduino. On top of the casing they say 0-10v pwm.

I opened them up to take some measurements. Starting from the top left. The first connector is the power to the LEDs. This reads ~86v at full power

The next connector which is the 4 pin connector. With leads places red on red and black on black. I get 0v when channel is off and (negative)3v when channel is at max. The green and yellow wires I get 8.5v when channel is off and 11v when channel is at max.but it's 8.5v from 0%-99% and then 11v when at 100%.

The next connector is for the cooling fan.

So the red and black of the four pin connector obviously carry the control signal for dimming the lights correct? Which the 4 pin connector connects to a small control board at the front of the until that contains a LCD and a rotary encoder and an IR receiver.

I'm confused because I was expecting either to find a control signal that went from 0-10v or a pwm signal. Which if it was controlled with pwm wouldn't I see it stay at 5v or would my multimeter interpret it similar to AC due to the duty cycle and the amount of time being off?

My first thought was well it's a 5v pwm signal. And maybe my meter is seeing 3v due to duty cycle and the amount of time off, but then I thought shouldn't it show 5v at max if it was pwm.

On the arduino if I change pwm value to 255 on a corresponding pin I see 5v.

What am I missing here?

Also there are two pots on the driver on is labeled min set. It's function is really neat and only affects the leds if brightness is set between 1% and 5%. But it allows me to lower the brightness even further. Normal minimum voltage for the blue channel is 73.1 but with that pot I can lower that minimum low enough where the leds barely glow something like 60v. I have not been able to discover what the function of the other pot labeled MP-W-SET yet.

Grumpy_Mike

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What am I missing here?
An oscilloscope.

A meter will not show any sort of sensible readings when measuring PWM. First off it is not AC and second it is at a very much higher frequency than the AC readings that meter is designed to cope with.

So basically the meter readings are a bit meaningless. Yes they go up and down but that is about all you can gather from it.

Jtroutt19

Well I realize an Oscope would be ideal here, Just don't have the cash to drop on that instrument. It's on the list.

Second I realize its not AC, Its a square wave that the duty cycle is varied on hence PWM. The thought of my Fluke maybe seeing it "like" ac even though the voltage never crosses zero was just that, a thought.

My meter can read the 490hz of the pwm pins, granted it doesn't allow me to view the actual waveform.

So, I guess I will simplify my question, I was just trying to give as much info as I could.

LED drivers that are dimmable use either a pwm signal or a analog voltage, I was always under the impression that an analog control signal would be 0-10 volts and a PWM signal would be 5v.

Any idea on to why I am not seeing that with these drivers?

Grumpy_Mike

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Well I realize an Oscope would be ideal here, Just don't have the cash to drop on that instrument. It's on the list.
Why not use and Arduino and a Processing program to make an oscilloscope? There are plenty of projects to copy on the web.

Jtroutt19

Fair enough, I have plenty of uno's laying around as well. I will look into it. On a different not I found out that the control signal is 3v3 pwm.

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