I found this little gadget in a discount store. It's an electronic tealight: a plastic device with an orange LED on top, that flickers in a random fashion to mimic a flame. I guess it's supposed to create a romantic atmosphere. Nothing more romantic than a plastic candle with a flashing LED on top!

And it's very plasticy indeed. It conforms to standard tealight dimensions though, so it will fit all your candle holders without modification.

This is what's inside. A tiny PCB with a glob-top: the cheapest IC package money can buy. The bare chip is bonded straight to the PCB, and covered with a glob of epoxy. Fast and cheap.

But check this out! The LED doesn't just flash in a random fashion, it's actually playing Beethoven's Für Elise, which you can hear if you connect a speaker to the LED. I guess that whoever designed these things was experimenting with chips from other cheap gadgets and found that these sound chips could just as well be used to make an LED flicker.

This is the chip. It's really tiny, just one millimetre on each side. In the top right corner there's a big transistor that drives the output. In the middle there's a memory area that holds the tune, and on the left we find a resistor and capacitor that determine the base frequency of the system.

When we switch to high magnification, we can easily see all the separate components. There are no markings anywhere on this chip to indicate its function or manufacturer.

The big square on the top left is the capacitor that sets the base frequency of the tune, together with the resistor (long, brown thing) right below it. The circuits on the right are probably a variable oscillator circuit.

Here's the memory that holds the tune. The vertical bars are running across a number of horizontal bars, and they are either connected to them (which you can tell by the presence of a little circle), or left unconnected. In this way, a number of 1's and 0's are encoded. The circuits on the right then read out each connection in order and drive the oscillator accordingly.