Harold “Doc” Edgerton, an American electrical engineer and photographer was noted for creating high-speed photography techniques. He developed and improved strobes and used them to freeze objects in motion so that they could be captured on film by a camera.
The ‘Piddler’ machine he created more than 50 years ago uses a stroboscopic technique to form optical illusions of levitating water droplets, slowing the downward flow of water as well as reversing the flow of water to move upwards to defy the laws of gravity. This inspired us to come up with our design of a Time Fountain.
With the water droplets in reverse, moving against gravity, it looks like the fountain is going back in time. Hence it is coined as a ‘Time Fountain’.
You may view the following YouTube to see a ‘Piddler’ machine in action.
We searched online for Time Fountain projects and found most setups are quite large. Fluorescent dye is often used in these projects to made the water droplets more visually appealing.
For our project, we attempted to design a compact Time Fountain which should be small enough to be carried around and we will not be using fluorescent dye as we hope kids can play with the water without any health concern. We will be using inexpensive small water pump and control valve to create a ‘stream’ of water droplets to be as uniform as possible and encase them in a small enclosure.
To build this project, basic electronics component soldering skill and some knowledge on using the Arduino is required.
You may like to view the following YouTube video to see what we will be building.

For this project, we have misused a solenoid valve to turn on and off the flow of water at rapid interval of 45 cycles per second in order to create a ‘stream’ of water droplets.
If you like this instructable, please vote for us in the Creative Misuse Contest at the end of this instruction. Thanks.
How it works?
No camera tricks are involved here. All these are stroboscopic technique optical illusions which we are able to see right before our eyes.
Water droplets are created by pumping them out of a tube at rapid and regular intervals to form a steady ‘stream’ of water droplets.
If the droplets are pumped out at a frequency of perhaps 45 Hz and illuminated with strobe light flashing at the same frequency, the droplets will appear to be essentially motionless and seem to be levitating in mid-air. When we see a droplet levitating in mid-air, the droplet is not exactly the same droplet. As the strobe light frequency is synchronized with that of the the falling droplets, every time the light is on it shows us the image of a different droplet at the same position. When the light is off, the droplet keeps falling and another replaces it.
By off-setting the frequency of the strobe light to a slightly lower frequency, the water droplets will appear to fall in slow motion. This is because the next droplet is actually slightly lower than the previous droplet when the light comes on and our brain interprets that as the same droplet moving downwards.
If the strobe frequency is off-set to a slightly higher frequency, the water droplets will appear to reverse back into the tube. This is because the next droplet is actually slightly higher than the previous droplet when the light comes on and we will perceive that as the same droplet moving upwards.
If the strobe light is turned off, the rapid water droplets falling will look like a continuous ‘stream’ of water falling to our unaided eyes due to Persistence of Vision.

CAUTION:
To a small percent of people with epilepsy, exposure to flashing lights at certain intensities or to certain visual patterns can trigger seizures. This project requires flashing of the LED strip lights at quite a high frequency which most people will not be affected by the flashing light. However, if you experience discomfort from direct or indirect light from the Time Fountain, you should stop looking at them immediately.”

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