Hacked Tea Lights Flicker Just Right

Flickering LED tea lights are a friendly and safe alternative to having flaming little pots of wax situated around your home, but sometimes the flicker scheme leaves something to be desired.

[Roger Rabbit] found a set of six such rechargeable tea lights with a base and a remote, and replaced the controller with an ATtiny85 for a more realistic flicker. When [Roger] opened up one of the candles, they found an IR sensor for the remote, a driver chip, and of course, an LED. No surprises there.

After desoldering the original controller, [Roger] wired in a socketed ATtiny85 on a piece of perfboard and hooked everything back up.The coolest part of this hack might just be the fact that there’s a perfect little compartment for the new microcontroller. How about that?

The Arduino code for this project is available in the Git repository, and the wonderful instruction manual is available in PDF form. Be sure to check out the brief video after the break.

You like these flickering LED candles? Here’s one you can blow out.

17 thoughts on “Hacked Tea Lights Flicker Just Right

  1. I once also tore down some seemingly similar looking “candle lights” (Mine were working on CR2032) and all the electronics were integrated in the LED itself. Looking at it though a microscope I could see a small black speck next to the LED and some extra bondwires.

    1. Interesting! I first saw flickering LED tea lights at the best pizza place in Gauteng (Gino’s) , and wondered whether the flickering was built into the LED or had a separate circuit. But surprisingly they didn’t let me do a tear down while tearing down my Quattro Stagioni.

    2. Just opened one, insanely basic: only a LED, with one leg directly in contact with CR2032 battery, and the other inserted in the switch that moves it in contact with the battery to turn it on!

      1. Indeed it is/was in many instances.
        Now that makes me wonder if you could get one of those super cheap recording versions of those card chips and use that to drive a LED with your own pattern based on a recording.
        That way every candle could be different and made to fit the surrounding,.

        BigClive showed a much impoved version of a LED candle though that had a much better pattern and implementation as I recall, but I guess they still have millions of the old style in warehouses to be sold for budget prices so I expect better won’t be the standard too soon.

  2. I thought I read here once that some of these flickering circuits were reused greeting card melody makers driving a LED.
    This is why I dislike web streams that use a phony spectrum display to show that we’re streaming and it’s always moving even during breaks.

    1. Yes, years ago I bought those which had something like this. I attached a loudspeaker and was able to hear the melody. Funny! Today they use more “specialized” algorithms I guess… ;)

  3. I did something similar with a the same Microcontroller, but inspired by the Phillips Led candle (very realistic) which used two(?) LEDs stacked vertically. This way I was able to “simulate” a change in the height of the “flame”, which made it look quite natural. (Not as good as the Philips ones but it came close)
    As input signal I used some random numbers with alot of averaging (like some kind of a lowpass).

  4. The best fake candle flame I ever saw has a plastic flame silhouette that can swing around an axis (maybe two axes, I don’t remember). It works by reflecting the light from the LED source below it while also being driven randomly by a small electromagnetic coil. The flicker effect comes from LED light output control plus the same frame small movements.

  5. I have found some of the designs have no visible driver, just one LED that either flickers from a defect or has an internal driver. You can create some interesting effects by wiring them together, as they seem to pass their effect into other LEDs, even normal LEDs. I used one to create a blue pulsing/flickering effect for a wife’s cosplay piece.

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