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In the latest beta version we added a tool to control electronics for creating water drop collisions. You will find a lot of solutions for capturing water drops on the web. They can be controlled manually without using any devices, just a pipette or something similar, but it is very hard to capture any usable photos. It's much more efficient to use a water (air) valve for generating water drops, but for this you need some electronics to control the valve So I decided to make one using information found on the Internet and make some experiments. This project it is in an experimental stage, but I hope we can make a useful solution at a low price.
In this project several electronics are involved. The base components are a solenoid valve and a microcontroller. I tried to assemble a cheap solution. For the valve I used a Chinese version from eBay available for 6.95$, the delivery time it is high almost 30 days. For a microcontroller I used an MSP430, which cost 9.99$. It was delivered in 48 hours. The MSP430 can be used almost in same way as an Arduino Uno microcontroller.
Some of the electronic components can be replaced with other similar components. The electronic schematic (click for a larger version, or right click and download for full size):
Optocoupler: 4N35, 4N26, 4N25
Transistor: 2N3904 or any similar which supports the valve power
The code for MSP430/Arduino can be downloaded from here. To upload the code to the MSP430 device I used Energia energia.nu/ which uses the same coding style as the Arduino controller. The same code can be used in both devices with minor modifications.
The user interface can be activated from digiCamControl using Menu->Tools->Water Drop Control. With this interface the timing can be set in real time. The camera should be set to bulb mode and manual focus.
The results (these are just simple tests with water):
In the near feature I plan to design a generic device to control multiple cameras, flashes, valves and get a light detector or a microphone as a trigger input device. Any suggestion about this are welcomed.
If somebody tries to develop the electronic part, I will glad to help in any way.
More about water drop photography: