What are those lights? Where to get them?
Want one.
What are those lights? Where to get them?
Want one.
I finally got the 2300K LEDs and tried them in my rechargeable tealight candles. I absolutely love it, it’s the closest I’ve been to a real candle light, and in a light holder of any kind it looks convincing.
From left: Original monochrome orange 3mm LED, 2300K LED and 3400K LED. Camera @5000K
Here they are with their included diffusers, looks pretty good. Can’t wait to solder all 12 of them and place them around the house.
I still use real candles on my living room table due to the cozyness and smell, but these are a lot safer to use unattended around the house, especially with cats around.
These Ikea lights have an integrated curcuit. I believe it’s these :
It’s just a tealight holder we’ve had for ages with Ikea tea lights inside :
Hey all, long time no see.
I would like to buy 100 pcs of 2300K 5mm LEDs.
I didn’t read the whole thread, so i’m not sure what you have in stock or if i should DM you, rngwm ?
Ah, okay !
You can PM me and choose the shipping option you desire (Pricing & fees in the OP).
If you want to make things easier for me, you can summarize the pricing in the PM for me.
(Tracked shipping is kinda pointless for Netherlands though, since it can’t really be tracked)
I hope you meant to say “10 in parallel to an AMC7135”. But why do you choose AMC7135 and PWM? :facepalm: The Arduino could be used to sense current over 3x sense resistor paths, precisely tuning a driving MOSFET VGS in each of them for accurate, PWM free linear current control.
I’ve read that’s not a good idea, but then I have not much clue about those things. I guess parallel is easier for the lower voltage needed?
Need to read about MOSFET circuits :weary: .
Ordered and paid. :+1:
No, that’s fine.
For 10 in series you need 32 29 Volts.
For 10 in parallel you only need 3.2 2.9 Volts, like from a single Li-Ion cell.
The AMC7135 will eat up a minimum of 150 mV.
In any case, driving leds in parallel could have some current sharing problems due to Vf differences between emitters. This can be minimized by binning leds with a multimeter, i.e. set them all extended over a table in a room with stable temperature for a little while first (acclimating emitters, they're sensitive to temperature) while laying a multimeter close, then use the multimeter to read and note down every emitter's Vf systematically at least once. Use the results to sort the emitters in Vf packs: 10 lowest, next 10, …, last and highest Vf 10-pack. This would minimize the above problem.
Well, as a word for caution, Vf disparity will be an issue.
The 3400k/5800k does have 0.1v higher Vf than 2300k.
I will, Barkuti. Thank you guys .
Will come back with questions when the project advances, I fear
Well, as a word for caution, Vf disparity will be an issue.
The 3400k/5800k does have 0.1v higher Vf than 2300k.
No problem. The colors will be driven seperately.
Just an update:
only 5 2 packs left for 2300k.
I will check up with my supplier on Monday and see if I can restock this 2300k tint.
There are many ways to drive emitters. Arrays of series emitters will display closer average Vf sum, this for example means it would be far better to drive a 10-pack in 10S or 2P5S arrangement. Watch out I said 2P5S, this means 2 parallel 5S arrays, which is a lot different than 5S2P. There are cheap boost DC/DC converters which can output that voltage from li-ion cells easily:
The MT3608 boost module is going to be reviewed by Henrik soon I think, sent him a 5 piece pack long ago. Now that I recall this, it was the 5th of August, he should have received the package sometime in September and we're almost in December already.
There are very few options for CRI95+ SMD MP LEDs with reasonably priced worldwide shipping.
Actually I have found literally just one offering on Aliexpres, for 2835 LEDs. Everything else seems to have expensive shipping.I suspect I’m missing something and I spend merely an hour or so on the search. But anyway - this is not something widely and easily available for a reasonable price.
About that CRI 95 SMD, you mean this one?
Smarter Shopping, Better Living! Aliexpress.com
Yes
Regarding driving LED’s in parallel, I think we can make some basic deductions from djozz’s data:
[image] I did a voltage and output test on one of these 3400K 95CRI leds, and it does not disappoint, output is better than the Yuji, voltage is lower, and it can handle more current. The max is about 22 lumen at 100mA, going higher up to 120mA gets you a bit more light for a moment but it settles back to 22 lumen again within a couple of seconds. My test rig for 5mm leds is not great, the current can not be set very well and the graph shows it, but the output numbers are correct. I also re-tes…
If you’re driving 10 at 350mA, that’s 35mA each.
From djozz’s graph, that’s about 2.95V.
If you had one LED in the group with a Vf that was lower and therefore hogging the current, then from the same data, I’d estimate the resulting current in the worst-driven LED as follows:
0.1V lower = 55mA
0.2V lower = 70mA
Since one of his survived an isolated test for 12 hours at 100mA, the over-current does not seem to be a problem. However, rngwn observed that if packed together, they heat up and may eventually run away:
I decided to make a light module out of 28 LEDs in parallel. Hooked it up to a lab bench. Without constant current regulation, any initial current above 840ma (30ma per LEDs) will result in a (very gradual) thermal runaway where the module start to pull more and more current and heat up more until it would presumably burn out. On the first try, I initially set the current at 1.4A, and it rose up to almost 1.6A within 10 minutes. Granted, these LEDs are packed fairly tightly together and thus…
So for the idea of running 10 on a 7135, I think heat is the main concern.
Yes, heat can be a problem in those 3xAAA 20 or more LED lights.
Especially those in the middle of the PCB can get hot on the crappy stock PCB they’re soldered on.
Good idea to epoxy a heat spreading disc on the back.