LED driver, voltage smoothing

[guyrj33]

I used this sort of PWM dimmer with LED strips.
Only issue was with the clamp on wiring leads not making secure connections.
https://www.amazon.com/DEVMO-DC12-24...xpY2s9dHJ1ZQ==

[roland stockham]

I can't think of a better way of smoothing a 12DC supply than adding dirty great battery. Voltage drop as battery discharges yes but fluctuation? Maybe you have a circuit issue (undersized cable probably would do it) or poor quality LED drivers. I have lots of LED, pretty much all lights and they are as steady as rock. Wiring is 3% drop max at full load on heavy draw items like the inverter and 1% for small loads like lighting.

[s/v Jedi]

Originally Posted by j.g.evans

Some readers suggest powering the LEDs from a constant current source and that is a good idea. Shorten your string and power the remaining LEDs from one of the suggested circuits. Removing 1 LED should drop the required voltage about 3 Volts which is about what a constant current circuit would require.
If you want to stay with 12V them go to mpja.com and get a DC-DC converter such as their 35075 PS. Put capacitors across the terminal too to prevent interference with your radios.

It’s impossible. One first needs to understand how these 12V LED products work before commenting. For one, these are all parallel groups of circuits, where each circuit is a series connection of led - resistor - led - led. It is built so that the resistor takes 3V voltage drop if 12.0V is connected, which leaves 3.0V per LED.

So you have to shorten per 3 led’s.

Also, about CC for LEDs: this is why there are not 4 LEDs but only 3 plus a resistor. It already is constant current and to function it requires a CV of 12.0V. If you want it different, you need to buy LEDs, resistors etc. and build your own lamp.

Here’s some info: https://www.waveformlighting.com/pcb...ge-information

[conachair]

Originally Posted by s/v Jedi

It already is constant current and to function it requires a CV of 12.0V.

That won't be constant current though as VF decreases with temperature.

Increase the temperature the current increases.

Though probably not a problem with cheap LED strings using resisters to limit the current.

[s/v Jedi]

Originally Posted by conachair

That won't be constant current though as VF decreases with temperature.

Increase the temperature the current increases.

Though probably not a problem with cheap LED strings using resisters to limit the current.

Temperature compensation? Really? Only done for high power LED applications; all the LED strips used for lights just use the series resistor.

Guys, it is what it is. Why don’t you design your improved LED strips and forward that to the manufacturers? Surely they will jump on it!

Or just cut one LED off the strip and see how that works. The manufacturers will love that as it saves them 33% of the cost of LEDs!

[conachair]

Originally Posted by s/v Jedi

Temperature compensation? Really?

Temperature compensation? No idea what your talking about. Are there really temperature controlled LED arrays out there?
The majority of LED drivers are constant current, not voltage. The voltage varies to keep the current constant so when the temperature and VF changes the current stays the same.
Masses on google about LEDs being current devices.

[s/v Jedi]

Originally Posted by conachair

Temperature compensation? No idea what your talking about. Are there really temperature controlled LED arrays out there?
The majority of LED drivers are constant current, not voltage. The voltage varies to keep the current constant so when the temperature and VF changes the current stays the same.
Masses on google about LEDs being current devices.

Oh my gosh

The diagram with 3 diodes and a resistor -is- a current LED driver diagram. It is oldest diagram out there, they taught me this when led’s were only available in red and green.

As these LED strips are manufactured by the hundreds of millions, and each one has many, many of these circuits on board, I’m pretty sure this still is the most used circuit. You take the LED(s), decide how hard to drive them, what your available voltage is and calculate the series resistor to set the desired current. I doubt if you ever actually did that, let alone learn this in class.

The catch is that this setup means that a small change in voltage results in a relatively big change in current and -that- is what the OP is experiencing. This is why LED strips require a stabilized 12.0V power supply. When you add a CV 12.0V power supply to the LED strip, in combination with the circuits on the LED strip, you get a CC driven light.

Here’s the basics: https://en.wikipedia.org/wiki/LED_circuit

[Sternwake]

I have one Phillips T10 LED on the same circuit as that powering my DC to DC laptop power supply.

It flickers badly, when powering both at the same time, but I can swap in a much cheaper T10 LED to the receptacle and it does not flicker.

I have put one of my xl4015 based buckers inline, and dim the Phillips t10 slightly, and it does not flicker. It only flickers if I ask it for max brightness.

So does the OP absolutely need max brightness of their LED ribbon lights?
Is 90% more than enough?

I find that 90% brightness draws about 65% of the current as 100% brightness does, though it depends on the specific LED being powered

The 3 for 15$ devmo PWM led dimmers linked above, are what I used to employ, I have them all in a bag now, replaced with 150kHZ xl4015 voltage bucker, as the latter do not flicker, do not whine, and allow the light to dim all the way to 0.005%, not just go to perhaps 20% brightness then shut off.

[David B]

Originally Posted by GILow

Hi all,

I’ve had great success using 12 volt LED strip lighting in the cabin. But the lights flicker with any kind of voltage variation.

Can anyone point me to a decent voltage smoothing solution? Each strip draws close to one amp, so I’d be looking for something that can handle that sort of current, or even a single device capable of four amps to run the whole cabin lighting circuit.

Happy to solder something up out of components if you think that’s the best approach.

Matt

They do a nice job don't they - can quite transform a cabin.

I use these in-line dimming modules, and typically run the strips at 60-80% depending which cabins they are in and whether concealed floor, or concealed shelf. No flickering has been noticed - just set and forget.

https://www.ebay.com.au/itm/12V-MINI...e515e8e9f229e6

There is also a remote control version if you want to 'play'.

https://www.ebay.com.au/itm/12V-RF-W...546dbdd0a138d1

Hope that helps.

David

[GILow]

Thank you David.

I’ll skip the remote option. The boat isn’t really big enough to justify it, plus it’s another thing to lose. But the first option looks great.

But yes, strip lights do look good, and they get around the problem of ceiling lighting glaring in your eyes at eye level, which is so hard to avoid on a boat.

[David B]

Originally Posted by GILow

Thank you David.

I’ll skip the remote option. The boat isn’t really big enough to justify it, plus it’s another thing to lose. But the first option looks great.

But yes, strip lights do look good, and they get around the problem of ceiling lighting glaring in your eyes at eye level, which is so hard to avoid on a boat.

No problem. Yet to be edited and published is the video of my little project in our fwd cabin. It was a wet day in Venice, and I decided it was the opportunity to finish what I had started the previous year. When I got everything complete and back together, I demonstrated to my First Mate, the difference between the normal downlights and the strip lighting at floor level, and up under the shelving/lockers, running along the sides of the hull. The resultant 'wow!' was at least as impressive as the lighting.

Lighting can be transformational - hence they use it a lot on up-market boats, but doesn't stop the likes of us folks doing something similar

[GILow]

Originally Posted by Sternwake

I have one Phillips T10 LED on the same circuit as that powering my DC to DC laptop power supply.



It flickers badly, when powering both at the same time, but I can swap in a much cheaper T10 LED to the receptacle and it does not flicker.



I have put one of my xl4015 based buckers inline, and dim the Phillips t10 slightly, and it does not flicker. It only flickers if I ask it for max brightness.



So does the OP absolutely need max brightness of their LED ribbon lights?

Is 90% more than enough?



I find that 90% brightness draws about 65% of the current as 100% brightness does, though it depends on the specific LED being powered



The 3 for 15$ devmo PWM led dimmers linked above, are what I used to employ, I have them all in a bag now, replaced with 150kHZ xl4015 voltage bucker, as the latter do not flicker, do not whine, and allow the light to dim all the way to 0.005%, not just go to perhaps 20% brightness then shut off.

Sorry, I missed this one. Helpful, thank you.

I’d be sorry to lose any brightness. The current setup is adequate, but only just. I still supplement it with a few strategically placed LED spotlights where I know I might need extra light from time to time.

But the power saving you recorded is very interesting. Something for me to ponder.

[Sternwake]

I have and use those 3 bubble button LED inline controller linked above for IP68 RGB strip lights.

The controllers get warm when the LEDs are not turned on, just when there is power to them, though their parasitic draw is low enough I cannot easily measure it and have not gone through the effort with tools that could.

Just the fact that the pushbutton controller is warm bothers me though.

My other ribbon/strip lights I have made various length portable 'wands' from a pine C channel, and ran at least two rows of warm white leds.

Using a Lightmeter app on my phone, the light reaching my worktable under a dual 8' fluorescent fixture, drawing 103 watts, is nearly the same as my 8' C channel with two rows of warm white leds, for 27 watts consumption. The Fluoro light has much more light off to the sides though. I could add two more rows of striplights to this light wand but require no more light than it outputs.

I wonder if a big old capacitor before teh LED input would smooth the flickering of the OP's leds, or slow it down enough to be tolerable

[GILow]

Originally Posted by s/v Jedi

I bought and tested these: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
but while converting some lights I skipped installing them and try without first. The nice thing is that you can set a fixed “dimming” point to reduce intensity to preference.

Just reporting back.

Happy to say that did the job perfectly, thank you SV/Jedi. I found the same device on the Australian Ebay site (https://www.ebay.com.au/itm/XL6019-B...72.m2749.l2649) for AU$10 and it has worked a treat.

My only complaint is that I can no longer tell when the Webasto furnace is doing its shutdown procedure, which used to make the lights go crazy.

But I think I can live with that.

[Nicholson58]

You might give these guys a look. https://www.murata.com/en-us