Originally Posted by 9dreizig (Post 6447504)

Each LED has a tiny inductor (L) and capacitor (C) across it. Each LC pair is tuned to a different frequency. The LC is a short at DC, but at f1, f2, f3, go high impedance and allow current through the corresponding LED. The switches have a resistor (R) and capacitor (C) in parallel across them. The C large enough to allow f1, f2, f3 through, and 3 different values for R. The battery has 3 oscillators, each of which is enabled depending on the DC current value - set by switches.

Originally Posted by 9dreizig (Post 6447507)

that was a quote from the youtube uploader

Originally Posted by Flieger (Post 6447869)

I do.

Basically it is a trick. The battery is not putting out DC, but three different frequencies due to the crystal oscillators. The switches each act as a filter to cut off a frequency. The LEDs are tuned to resonate (light up) at a certain frequency, so depending on the switches' positions, different frequencies reach the LEDs and only the LED that is tuned for a certain frequency will light up. Any other frequencies will not cause it to light up, unless the resonant frequency is also coming in (since you can superimpose frequencies).

This is mostly a demonstration of the cool things you can do with resonance.