Dimmable HLG driver Optocoupler or Transistor, does it matter? (and other questions)

shimbob said:

Oops, wrong thread.

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That's ok, both threads really deal with the same principle.

The AC infinity seems to be the same as the meanwell except that I do not have a ground to connect to HVG on the meanwell.

With the info you provided I think I should be able to get this going without frying anything.

Thank!

GND to DIM-, pwm out to DIM+

I had a conversation with someone who had a T6 (or T8, I forget) controlled by an arduino. But the T- series rely on the remote to make 10V, unlike the S-. His solution to getting it PWM-controlled was to force the remote control to always 100% fan output, this made the remote output a solid +10V, which he then fed to his optoisolator High IN, and pwm output to the fan.

shimbob said:

I had a conversation with someone who had a T6 (or T8, I forget) controlled by an arduino. But the T- series rely on the remote to make 10V, unlike the S-. His solution to getting it PWM-controlled was to force the remote control to always 100% fan output, this made the remote output a solid +10V, which he then fed to his optoisolator High IN, and pwm output to the fan.

Click to expand...

This is interesting as the control unit itself has no power but takes power from the connector coming from the fan. (4 pin connector).

Either was, it make it slightly more complicated but not out of my realm of ability yet!

I really appreciate the follow ups. When I get a chance to try this between grows (waiting on 2 plants finishing up), I'll post back!

Thanks again!

I can't attest to the accuracy of this schematic, but this is what others claim the dimmer circuit looks like. So vm1 seems to be seeing the voltage across c1. R2 and c1 form a low pass filter allowing dc 0 to 10v through. If this is accurate i would think a simple transistor or optocoupler would work fine assuming the switching speed is adequate


https://www.eevblog.com/forum/projects/mean-wells-2-in-1-dimming/msg1835957/#msg1835957

Attikus112 said:

I can't attest to the accuracy of this schematic, but this is what others claim the dimmer circuit looks like. So vm1 seems to be seeing the voltage across c1. R2 and c1 form a low pass filter allowing dc 0 to 10v through. If this is accurate i would think a simple transistor or optocoupler would work fine assuming the switching speed is adequate

View attachment 4725976
https://www.eevblog.com/forum/projects/mean-wells-2-in-1-dimming/msg1835957/#msg1835957

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I'd need to learn quite a bit more to understand what that schematic is telling you as far as how safe it would be to connect to it without isolation of some sort. However, it does seem inline with what I see on other forums, and, if I don't care about frying a raspberry PI, I suspect a short is actually fairly unlikely being it is a quality driver.

shimbob said:

I had a conversation with someone who had a T6 (or T8, I forget) controlled by an arduino. But the T- series rely on the remote to make 10V, unlike the S-. His solution to getting it PWM-controlled was to force the remote control to always 100% fan output, this made the remote output a solid +10V, which he then fed to his optoisolator High IN, and pwm output to the fan.

Click to expand...

I took this photo, manual says the controller is compatible with S and T type fans of the same size. I plan to play with it once I am done my current cycle as I don't want to destroy my fan while I need it still, but if it can control both, I wonder where the 10v is coming from. Either way, it seems there is a solution!

Relic79 said:

I'd need to learn quite a bit more to understand what that schematic is telling you as far as how safe it would be to connect to it without isolation of some sort. However, it does seem inline with what I see on other forums, and, if I don't care about frying a raspberry PI, I suspect a short is actually fairly unlikely being it is a quality driver.

Click to expand...

The isolation is nice to have and will protect your RPi in the event of a catastrophic failure of the Meanwell supply. I've been controlling my LPF-60D for three years without isolation and I haven't had any issues. The datasheet for the Meanwell supplies mentions something about the max current from the dimmer circuit being 0.1mA so it's not like we're trying to control mains power with this thing. You're working with a feature of the driver that's intended to interface with a third party hardware solution. Meanwell is one of the few brands of LED drivers and AC/DC converters that I trust and like you, I don't really care if I take out my $10 RPi zero w. I'm in the process of coming up with a control scheme for a new cabinet I'm building so i'm going to do a quick check with an optoisolator and PWM generator this weekend to see if a single component is sufficient for dimming. Seems like a pretty common scheme. If the schematic I linked is accurate it should work.

I did a quick test today with a Meanwell LPF-60D-54, PC817 optocoupler, 10K resistor and a PWM generator. PWM generator + and - were connected to pins 1 and 2 of the optocoupler, and I tested two configurations for the DIM+ and DIM- connections. I didn't use a current limiting resistor for the optocoupler inputs but it would be a good idea. I tested PWM frequency between 75Hz and 1kHz, below 100Hz the lights were flashing and towards the 1kHz, I don't think the PC817 could keep up. I'll stuck with 150Hz for the rest of my tests.

First configuration was DIM+ connected directly to the PC817 collector (4) and DIM- to the PC817 emitter (3). A duty cycle of 100% was the dimmest setting, and 0% was the brightest. I did notice some odd behavior at the dimmest setting using this configuration. The LPF-60D is supposed to dim between 10% and 100%. This was turning the light off completely and I needed to bump the duty cycle up a few % to get it to turn back off. This is the same behavior I see with my potentiometer dimming setup so it might be fine, but this LED driver doesn't have the newer dim-to-off 3-1 so i don't trust that behavior.

For the second configuration, I added a 10K resistor between dim+ and the PC817 cathode, dim- was still connected to the PC817 emitter. With this configuration everything seems to work as described in the datasheet. Same as before 100% is the dimmest, 0% was the brightest, but the light didn't dim-to-off with this setup. From this quick test, I would say a simple optoisolator/optocouple setup with PWM is sufficient for dimming.