EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Lucky-Luka on April 16, 2021, 02:25:12 pm
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Hi all
I've analyzed an LED taken from a votive candle.
Why is it flickering (they do that to remeber the fire of wax candles)? What's inside of it?
https://youtu.be/opU5CsuhHgA
Thanks
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There is an IC driver doing that. I didn't find a die shot of what you have, so I propose to look at ws2812 die shot: http://mirekk36.blogspot.com/2013/09/co-to-jest-czyzby-powrot-do.html (http://mirekk36.blogspot.com/2013/09/co-to-jest-czyzby-powrot-do.html) .
If you are curious about die shot, check this website: https://richis-lab.de/Bipolar20.htm (https://richis-lab.de/Bipolar20.htm) . Or check posts from Noopy on this forum. Like https://www.eevblog.com/forum/projects/lm723-die-pictures/ (https://www.eevblog.com/forum/projects/lm723-die-pictures/)
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Noopy's thread on optoelectronics is interesting.
https://www.eevblog.com/forum/projects/optoelectronics-die-pictures/ (https://www.eevblog.com/forum/projects/optoelectronics-die-pictures/)
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I saw Ikea LED candles all flickering exactly the same. I shut them off and then turned them on at the same time, and they were all synchronized.
They seem to be reading a pattern in ROM and just cycling through it. That should be part of the IC in OP's LED.
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I saw Ikea LED candles all flickering exactly the same. I shut them off and then turned them on at the same time, and they were all synchronized.
They seem to be reading a pattern in ROM and just cycling through it. That should be part of the IC in OP's LED.
After seeing some rumours on the web, I tried hooking a piezo sounder across the leds on a bunch of old LED candles (COB rather than embedded in the LED). A few types did indeed play nice little oriental tunes - clearly dual use greeting card ICs. Others just produced nasty random noise, so at least some have (had) ROM lookup.
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After seeing some rumours on the web, I tried hooking a piezo sounder across the leds on a bunch of old LED candles (COB rather than embedded in the LED). A few types did indeed play nice little oriental tunes - clearly dual use greeting card ICs. Others just produced nasty random noise, so at least some have (had) ROM lookup.
Can you explain better what you have done?
It's amazing (for me) the technology hidden in these cheap LEDs!
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Oh yes, that famous little oriental tune: https://en.wikipedia.org/wiki/F%C3%BCr_Elise (https://en.wikipedia.org/wiki/F%C3%BCr_Elise)
https://www.instructables.com/Listen-to-a-led-tea-light/ (https://www.instructables.com/Listen-to-a-led-tea-light/)
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We had a thread earlier that wandered into those little electronic candles - your pic was similar to mine https://www.eevblog.com/forum/chat/a-burning-candle-in-epoxy-resin/msg3106588/#msg3106588 (https://www.eevblog.com/forum/chat/a-burning-candle-in-epoxy-resin/msg3106588/#msg3106588)
Those little things do a poor job of simulating a candle flicker. If you are interested, check out this guys attempt https://cpldcpu.wordpress.com/2016/01/05/reverse-engineering-a-real-candle/ (https://cpldcpu.wordpress.com/2016/01/05/reverse-engineering-a-real-candle/) very well thought out and analyzed in my view.
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I once saw some extremely cheap "flickering candle" lights that had a curiously short and repetitive pattern: three short blips, then three slightly longer blips. ::)
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Oh yes, that famous little oriental tune: https://en.wikipedia.org/wiki/F%C3%BCr_Elise (https://en.wikipedia.org/wiki/F%C3%BCr_Elise)
https://www.instructables.com/Listen-to-a-led-tea-light/ (https://www.instructables.com/Listen-to-a-led-tea-light/)
Interesting, I would certainly have recognised that one! The tune from mine was definitely oriental in nature, quite delicate. I wonder how many variations there are out there. Presumably only on the older candles.
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I've tried with my LEDs but their tune doesn't mean anything :(
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My understanding is that flicker LED candles with external chips might play a tune as they re-use sound-chips. LEDs with an integrated flicker chip use specific PRBS chips. Probably the sound chips are too big to fit in a LED housing.
By the way. Here is one candle LED that is a bit more realistic:
https://www.youtube.com/watch?v=Y96owyGh2Pw&t=1s (https://www.youtube.com/watch?v=Y96owyGh2Pw&t=1s)
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Yes, I'm sure the dies integrated into LEDs are optimised for minimum size and best function, rather than re-purposing existing ones.
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After seeing some rumours on the web, I tried hooking a piezo sounder across the leds on a bunch of old LED candles (COB rather than embedded in the LED). A few types did indeed play nice little oriental tunes - clearly dual use greeting card ICs. Others just produced nasty random noise, so at least some have (had) ROM lookup.
At some point I thought it's some 1st April joke. ;D
Mine were from LIDL, with a single CR2032 batt from around year 2015.
They don't sing, only buzz in single tone pulses. :-\
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We had a thread earlier that wandered into those little electronic candles - your pic was similar to mine https://www.eevblog.com/forum/chat/a-burning-candle-in-epoxy-resin/msg3106588/#msg3106588 (https://www.eevblog.com/forum/chat/a-burning-candle-in-epoxy-resin/msg3106588/#msg3106588)
Those little things do a poor job of simulating a candle flicker. If you are interested, check out this guys attempt https://cpldcpu.wordpress.com/2016/01/05/reverse-engineering-a-real-candle/ (https://cpldcpu.wordpress.com/2016/01/05/reverse-engineering-a-real-candle/) very well thought out and analyzed in my view.
The same guy analyzed one of these flicker flame LEDs.
https://cpldcpu.wordpress.com/2013/12/08/hacking-a-candleflicker-led/ (https://cpldcpu.wordpress.com/2013/12/08/hacking-a-candleflicker-led/)
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Mine were from LIDL, with a single CR2032 batt from around year 2015.
They don't sing, only buzz in single tone pulses. :-\
The Germans have no sense of humour! ;D
(Sorry, that was very politically incorrect!)