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Chip on Board LED strip

willbish

By willbish
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willbish Regular Member

willbish

Posted
Posted

Looking for any recommendations for LED strip suppliers, preferably UK

Specifically after 12v Chip on Board COB

Ive seen some 12v versions can be cut at 25mm intervals which would be a lot better for reducing any dull spots at the ends of the profiles I have plastered in.

The LEDYI range is excellent but purchasing direct from China land is adding $$ in shipping

 

 

Radian Advanced Member

Radian

Posted
Posted

Have you checked on Amazon? Seem to have plenty there and will be warehoused in UK or Europe. May be worth trying Prime if you're not already using it. Might I also recommend going for 24V... it will improve brightness over full length if you intend to use several meters in one continuous length.

willbish Regular Member

willbish

Posted
  • Author
Posted
  On 06/05/2022 at 18:17, Radian said:

Might I also recommend going for 24V... it will improve brightness over full length if you intend to use several meters in one continuous length.

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Ive bought a few 12v transformers already but still have a couple to buy. Haven't seen any 24v that has 25mm cutting intervals all seem to be 50mm which puts me off

 

Would 24v 15W/m really be brighter than 12v 15W/m? Longest length I have is 5 metres

 

Radian Advanced Member

Radian

Posted
Posted
  On 06/05/2022 at 18:40, willbish said:

Would 24v 15W/m really be brighter than 12v 15W/m? Longest length I have is 5 metres

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It's the uniformity of brightness that is impacted by length. The reason being that the resistance of the copper tracks connecting the LEDs causes a volt-drop that increases along the length. This means the LED's furthest from the cable entry can be noticeably dimmer and show a slight colour temperature shift. 24V tape overcomes this in two ways: the current is halved, hence worst case volt-drop is halved for a given length of tape. Also, there are a few volts extra headroom for the current limiting resistors to operate within which makes their effect more linear.

 

These effects can be mitigated in 12V tape through two mechanisms: the power can be fed in at both ends so causing the middle of the tape to experience the maximum volt-drop (which will be half as much as when fed from one end only) and 'professional' constant current tape which replaces 'dumb' resistors with transitor based current limiting. This dynamically compensates for varying volt-drops and produces uniform illumination.

 

5m really is pushing it for 12V tape. I have a 2m long tape that I can see is dimmer at the far end. You too are probably doomed (and anyone else reading this) now that I've mentioned it. 🤣

  • Like 1
Nickfromwales Advanced Member

Nickfromwales

Posted
Posted (edited)
  On 06/05/2022 at 18:40, willbish said:

 

Ive bought a few 12v transformers already but still have a couple to buy. Haven't seen any 24v that has 25mm cutting intervals all seem to be 50mm which puts me off

 

Would 24v 15W/m really be brighter than 12v 15W/m? Longest length I have is 5 metres

 

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5m is the norm, and cutting at 25mm very very rare. Usually in 3 chip segments and at 50mm or so.

I bought from Govee for my kids rooms, with addressable LED’s, chips on strip, and I am very very happy ( for the price ).

Zero evidence of dimming or colour rendition fading through the 5m strip, and I was prepared to add a second connection to create a ‘ring’ but absolutely no need whatsoever.

I bought via amazon, £35/5m iirc……cheaper than shoplifting.

Edited by Nickfromwales
Radian Advanced Member

Radian

Posted
Posted

There may be ways of 'filling' the light to the ends if you get really unlucky with the cut-points. You might be able to overlap a small stub wired in parallel at the feed-in point for instance. It will depend on how thick the tape is and how much room you have. If your profile has a diffuser that will help blend things out.

Nickfromwales Advanced Member

Nickfromwales

Posted
Posted (edited)

£35 for 10m kit. Just checked my history.

 

EDIT, price has gone up to £39.99….

 

Could be a deal breaker for the few ‘financially prudent’  folk on here. :) 

Edited by Nickfromwales
Radian Advanced Member

Radian

Posted
Posted
  On 06/05/2022 at 20:54, Nickfromwales said:

Thus eradicating your aforementioned concerns. ;) 

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Indeed - one of the mitigations I mentioned earlier but, unfortunately for willbish, not available in COB form.

 

Interestingly there's a relatively new integrated pixel IC in the WS28XX series - the WS2815. The first iteration being the WS2811 which is an SO8 IC that can tolerate 12V and sink current for up to three seriesed 5050 RGB LEDs. Then came along the WS2812 which was the first to integrate the RGB LED and driver within the same 5050 package. These have the highest pixel density but can only operate with a 5V power rail. This is a nightmare as the current is three times higher than the 12V tape and things really do go south at the end of a 5m run. But now there's the WS2815 which can tolerate up to 12V per LED. This extra headroom allows for long tape lengths without colour shift/brightness uniformity problems but at the expense of actual brightness. In order to dissipate the higher volt-drops in the IC's the LED current is significantly restricted. Not much of a step forward really but it demonstrates there is a problem in the world of LED tape.

  • Like 1
Nickfromwales Advanced Member

Nickfromwales

Posted
Posted
  On 06/05/2022 at 21:12, Radian said:

Indeed - one of the mitigations I mentioned earlier but, unfortunately for willbish, not available in COB form.

 

Interestingly there's a relatively new integrated pixel IC in the WS28XX series - the WS2815. The first iteration being the WS2811 which is an SO8 IC that can tolerate 12V and sink current for up to three seriesed 5050 RGB LEDs. Then came along the WS2812 which was the first to integrate the RGB LED and driver within the same 5050 package. These have the highest pixel density but can only operate with a 5V power rail. This is a nightmare as the current is three times higher than the 12V tape and things really do go south at the end of a 5m run. But now there's the WS2815 which can tolerate up to 12V per LED. This extra headroom allows for long tape lengths without colour shift/brightness uniformity problems but at the expense of actual brightness. In order to dissipate the higher volt-drops in the IC's the LED current is significantly restricted. Not much of a step forward really but it demonstrates there is a problem in the world of LED tape.

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Yup. They could just make the strip a little bit wider and add more cross sectional area to the conductors…..Not sure why they are all thinking smaller is better tbh, as the increase would be relatively marginal.

willbish Regular Member

willbish

Posted
  • Author
Posted
  On 06/05/2022 at 21:12, Radian said:

Indeed - one of the mitigations I mentioned earlier but, unfortunately for willbish, not available in COB form.

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Perhaps for the areas where a longer run is required I should look beyond COB? They will be behind diffusers after all.

One area in particular has the 12v transformer already wired in the ceiling, which will be accessible when I eventually cut a hole for a ceiling speaker, but has 2x lengths at 4.6m. Im not after any RGB just 3000K

Radian Advanced Member

Radian

Posted
Posted
  On 07/05/2022 at 18:49, willbish said:

 

Perhaps for the areas where a longer run is required I should look beyond COB? They will be behind diffusers after all.

One area in particular has the 12v transformer already wired in the ceiling, which will be accessible when I eventually cut a hole for a ceiling speaker, but has 2x lengths at 4.6m. Im not after any RGB just 3000K

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The COBs are nice for even illumination. I don't know of anything better really. You might have room to lay a pair of wires parallel with the strip to take power to the far end? It really is a matter of trying some as you can't guess how much copper they use in any given product. The width could be a clue but they're usually all close to 10mm.

willbish Regular Member

willbish

Posted
  • Author
Posted
  On 07/05/2022 at 21:32, Radian said:

 

The COBs are nice for even illumination. I don't know of anything better really. You might have room to lay a pair of wires parallel with the strip to take power to the far end? It really is a matter of trying some as you can't guess how much copper they use in any given product. The width could be a clue but they're usually all close to 10mm.

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Thanks @Radian

There may even be an option to get a cable to the other end of the profile direct from the transformer, via the ceiling void, if the COB doesn't perform as I had hoped.

Hadn't considered running cable in the profile, pretty sure that would work too.

Nice to have a few back up options 👍🏼

 

Will likely press ahead with the LEDYI quote. Just a shame their products doesn't have a UK stockist

 

 

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