I was inspired by some others projects on internet (like this, for example: http://www.youtube.com/watch?v=ZRlNOyxWWf8& )
This "Time Fountain" works by the principle of the Stroboscope: http://en.wikipedia.org/wiki/Stroboscope
I made this fountain using a little submersible water pump inside a decorated jar, fluorescent water (with highlighter's ink) and UV LEDs, to obtain strobe light, using a simple strobe circuit based on a pair of ne555 (with a low duty cycle).
With this circuit we obtain a strobe light with duty cycle and frequency both adjustable via two potentiometer.
The transistor (2N1711) can handle a maximum current of 500 mA.
I used 18 LEDs UV.
My Time Fountain video :
Is very important to obtain a regular drip rate, for this i've used an infusion medical kit like this: http://servizimedia.altervista.org/fontana/img/Contagocce.jpg
The water is pumped upward, through a tiny pipe, and falls again inside the jar, cyclically.
With the strobe light (with a potentiometer we can set the frequency of lamps) i can set the effect on the drops, as you can see in the video. The drops are constant, i just change the LEDs frequency.
With strobe light we get the illusion of freezing the drops of water in midair, slowed or reversed!
My Time Fountain video II (click here if the player don't works )