![candle flicker candle flicker](https://www.taralane.ie/image/cache/intact/W880ALT1-1000x1000.jpg)
![candle flicker candle flicker](https://i5.walmartimages.com/asr/8a838824-1397-4455-a2dc-fd23d511cc18.3d618c65a4c776f469362b0eed7c0223.jpeg)
This corresponds to 13-14 updates per second. Each “frame” of equal brightness is exactly 32 cycles and lasts around 72 ms. Coincidence? Or did the designer lift the oscillator from a music playing circuit? (So there is some truth to the rumor of these LEDs being musical). This means that we are looking at a digital circuit, no weird analog trickery.Ĭuriously the frequency of the signal is around 440Hz, the concert pitch standard. The makes sense, because a real candle is at maximum brightness most of the time, interrupted by short periods of “flicker”.Ī closer look reveals that the signal is pulse width modulated. It is obvious that there are periods where the LED is fully turned on and there are intervals when the LED is modulated in some way. The diagram above shows about a minute of LED brightness variation sampled at 1MHz. The variable resistor has to be adjusted so that it is large enough for the logical analyzer to see a current increase as ‘one’, but still allow the LED to function properly. I used this to extract the “control signal” to the LED and capture it with a logic analyzer, as shown in the circuit diagram.
#CANDLE FLICKER SERIES#
Alternatively, the voltage drop across a series resistor is modulated in the same way as the LED brightness. A second LED connected in series shows a very similar brightness modulation. This is based on the fact that the LED draws more current when it is turned on by the controller. They also showed that they can be used to control another LED. They showed that they are “musical” by translating brightness variations to sound. A third bond wire is connected to the anode of the LED chip, while the cathode is connected to the negative lead.Įvil Mad Scientist looked at very similar LEDs a while ago. The controller chip is connected to both the positive and the negative leads. The standard 5 mm LED package contains a small LED-Chip and a slightly larger integrated circuit. This raises another question: Are these cheap LEDs really worse than all the self-made microcontroller based LED-candles around the web? But the interesting part is of course: How do they work? Considering that they literally sell for a few cents a piece, there can not be very expensive electronics involved. Very nice, you can not do that with real candles.