24v LED D4 DMX Dimmers from Amazon/AliExpress/etc.

[Rob_in]

Hi,

A couple of my EldoLED 180D dimmers have died again and I have to say, this is a bit annoying as they don't seem very reliable here. It might be related to lightning strikes, but even so, kindof a pain.

It's been some years since I originally spec'd this stuff and things may have moved on so am tempted to try some of the D4 Dimmers that are available at Amazon, AliExpress, etc.

This kind of thing:

Just wondering if anyone has an experience using the 24v version with LEDs and will they dim down to 1% with no flicker? The doco says the PWM frequency can be set as high as 2Khz so flicker really shouldn't be noticeable but I'm sceptical.

Would love to hear any experiences. Maybe I should just order one from Amazon and send it back if it sucks?

TIA,

Robin

[Duncan]

i have them but not for driving leds so cant comment on the dimmability or flicker, i use them to drive SSRs turning them in to dmx SSRs

they have been reliable for 5 yrs or so, so maybe that helps

[Steve Joyner]

I’ve been using some of these for about a year to run RGBW LED strips, but I’m not really using any diming as part of the setup.  The LEDs are just on or off in various colours, but only dimmed as fade in/out so I can’t really comment on the flicker at low levels.

I can say that the dimmers have been stable so far (despite being in a hot loft space) and I’ve not noticed any flicker at full brightness.

Steve

On 29 Jul 2022, at 07:41, Rob_in <rain...@gmail.com> wrote:

Hi,

A couple of my EldoLED 180D dimmers have died again and I have to say, this is a bit annoying as they don't seem very reliable here. It might be related to lightning strikes, but even so, kindof a pain.

It's been some years since I originally spec'd this stuff and things may have moved on so am tempted to try some of the D4 Dimmers that are available at Amazon, AliExpress, etc.

This kind of thing:

<H198886ffa3c54ffd9ec9f16be2fa6e51P.jpg>

Just wondering if anyone has an experience using the 24v version with LEDs and will they dim down to 1% with no flicker? The doco says the PWM frequency can be set as high as 2Khz so flicker really shouldn't be noticeable but I'm sceptical.

Would love to hear any experiences. Maybe I should just order one from Amazon and send it back if it sucks?

TIA,

Robin

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[Steve Joyner]

I’ve been using some of these for about a year to run RGBW LED strips, but I’m not really using any diming as part of the setup.  The LEDs are just on or off in various colours, but only dimmed as fade in/out so I can’t really comment on the flicker at low levels.

I can say that the dimmers have been stable so far (despite being in a hot loft space) and I’ve not noticed any flicker at full brightness.

Steve

On 29 Jul 2022, at 07:41, Rob_in <rain...@gmail.com> wrote:

Hi,

A couple of my EldoLED 180D dimmers have died again and I have to say, this is a bit annoying as they don't seem very reliable here. It might be related to lightning strikes, but even so, kindof a pain.

It's been some years since I originally spec'd this stuff and things may have moved on so am tempted to try some of the D4 Dimmers that are available at Amazon, AliExpress, etc.

This kind of thing:

<H198886ffa3c54ffd9ec9f16be2fa6e51P.jpg>

Just wondering if anyone has an experience using the 24v version with LEDs and will they dim down to 1% with no flicker? The doco says the PWM frequency can be set as high as 2Khz so flicker really shouldn't be noticeable but I'm sceptical.

Would love to hear any experiences. Maybe I should just order one from Amazon and send it back if it sucks?

TIA,

Robin

[Toby Mills]

I drive my whole house with the 36V version. Not a single failure but I have 4 in the panel ready to go if one ever does fail.
I think a lot depends on the LEDs you drive with them, we are using sunset dimming lights from Switch Lighting and they work great.
https://switch-lighting.co.nz/

We drive the whole house off a 24V battery bank with Solar and mains fallback which directly drives the Loxone System and then use a 24V to 36V DC converter to bring it up to the right voltage to drive these dimmers and the leds.
We live in an area with heaps of power cuts so its great that lights, internet etc all keep working when the power goes off without having to invest in an inverter etc.

Photo of the panel below.

[Toby Mills]

I should have posted my DC panel as well as that might be useful.

The Meanwell power source goes through disconnects, current met (top) then through a relay so it can be disconnected by Loxone then a breaker and into the Suntrack Duo which allows two DC sources to chare a battery bank (one from Solar and one from Mains DC).
Solar panels come in, go through disconnect, through current meter then also through a relay and breaker into the Suntrack.
House / Loxone / Lights is fed via the battery bank side of the suntrack but also goes through a current meter and breaker.

Loxone measures the current via the Loxone Extension using the 0-10V current meters.
It measures voltage using the Tycon box on the right which supplies as a virtual input over ethernet to Loxone.

Loxone monitors sun height and tests the panels to see if they can supply enough current to charge, then it disconnects the mains DC and feeds everything off the solar panels. If the battery draw is too high it switches back to DC mains.
In the event of a power outage, loxone monitors power consumption and changes the operating mode to reduce light brightness and conserve power etc.

A setup like this makes it feasible to drive a good chunk of your house off low voltage DC.

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[Rob_in]

Thanks all for your feedback. They do sound like a possibility.

On Saturday, 30 July 2022 at 02:34:05 UTC+2 mil...@np.co.nz wrote:

I drive my whole house with the 36V version. Not a single failure but I have 4 in the panel ready to go if one ever does fail.
I think a lot depends on the LEDs you drive with them, we are using sunset dimming lights from Switch Lighting and they work great.

Sounds promising... when you ask Loxone to dim to 1%... does that work without flicker?

Thinking logically (tell me if this is wrong), a 1% duty cycle - yes, yes, don't worry about logarithmic stuff for now ;) - even at 2Khz would produce a 20hz pulse wouldn't it? And 20hz is kindof borderline for perceptible flicker.

Cheers,

Robin

[Duncan]

you are misunderstanding pwm - the % dimming doesnt affect the frequency rate, it affect the % of the on time that the led is lit (the duty cycle)

see

https://en.wikipedia.org/wiki/Pulse-width_modulation

https://learn.sparkfun.com/tutorials/pulse-width-modulation/all

the on/off of the leds will always be at the same frequency

becauses leds are instant on/off, if they are on for a very short part of each cycle (eg dimmed to a few %) the eye may notice the leds turning off, creating a flickering sensation

when the pwm frequency is at a higher rate, the eye cant perceive the on/off and smoothes out the result

[Rob_in]

On Saturday, 30 July 2022 at 17:59:56 UTC+2 Duncan wrote:

you are misunderstanding pwm...

I don't think so ;)

 

Think about it: say we have a 2KHz PWM frequency. This means that every second is split into 2,000 parts. The LED can either be on, or off, for any number of these parts across each second.

At 100% duty cycle, the LED is on for 100% of the time: every single one of the 2,000 parts.

At 50% duty cycle, the LED is on for 50% of the time: it's on for 1,000 of the 2,000 parts each second. Ie. the LED is on for 1/2000 of a second, then off for 1/2000 of a second, etc.

At 25% duty cycle, the LED is on for 25% of the time: it's on for 500 of the 2,000 parts each second. Ie. the LED is on for 1/2000 of a second, then off for 3/2000 of a second, etc.

The above examples are not a problem for flicker as the ratio between 'parts on' and 'parts off' is pretty small. But...

At 1% duty cycle, the LED is on for 1% of the time: it's on for 20 of the 2,000 parts each second. Ie. the LED is on for 1/2000 of a second, then off for 99/2000 of a second, etc.

So what this actually means is that using a PWM frequency of 2KHz at a 1% duty cycle the LED would turn on (very briefly - for 1/2000 of a second) and then off (for 99/2000 of a second) and this cycle repeats 20 times each second. In theory one would notice that flicker (there's a reason why video generally runs above 20fps). That's what I'm worried about.

Robin

[Vladimír Třebický]

Hey all. If it's of any help, I'm petty sure Duncan is right on this one:

https://en.m.wikipedia.org/wiki/Pulse-width_modulation

The on/off cycle repeats at given frequency (takes exactly 1/f time). Duty cycle refers to the *fraction* of the cycle the signal is on vs. off.

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[Rob_in]

On Saturday, 30 July 2022 at 19:46:36 UTC+2 vladimir...@gmail.com wrote:

Hey all. If it's of any help, I'm petty sure Duncan is right on this one:

If this is true, then all good, because it would mean that even at the 'low' 500Hz frequency setting, the D4 dimmers should have no discernible flicker, right down to a fraction of a percentage of duty cycle (well - as much as 8 bit precision will give you).

So they *should*... but do they?

Robin

[Toby Mills]

You don’t notice them flicker. 

BUT at 500hz there is noticeable flicker in videos. 

At 2000hz this is gone.  

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[Duncan]

the visible flickering on video is a 'beat fequency' effect, where 2 different frequencies interact (in this case the dmx dimming rate and the video frame rate) - the difference between the 2 shows up sometimes as a flicker, and could happen when you have 2 visible light sources at different frequencies such as using 2 dimmers set at different frequencies within the same area

https://en.wikipedia.org/wiki/Beat_(acoustics)#:~:text=Binaural%20beats,-Binaural%20beats&text=A%20binaural%20beat%20is%20an,(one%20through%20each%20ear).

is a technical explanation of the audio version, but the same applies to light just the same

if 1 is an exact multiple of the other you would not expect to see it at all, and if the resultant beat frequency is high enough (eg in the 2k example noted above) then the eye cant perceive it anyway