If you want to capture water drops with little effort: Welcome. I started an Arduino project to show you simple this task is in reality. YOu just need a few components and not a huge amount of time to build everything. The circuit is supported by the Arduino Uno (you can also use a Nano).
As I said the setup is easy, I used the following parts:
|1||Resistor||10kΩ||For the button|
|1||IR-LED||880nm||Left on the breadboard|
|1||Phototransitor||620-960nm||Right on the breadboard|
|1||Camera connector||Is explained later|
The wiring is done like I showed here, but I didn't put the IR-LED and the phototransistor directly on the breadboard, no, I connected them via cables. Otherwise the drop would have to pass the breadboard. Please note that the LED and the phototransistor have to face each other with a distance of about 10-30mm so that the drop can fall through.
The camera connector is a simple 3.5mm stereo jack. Many cameras and flashes support this. For water drop photography I recommend a flash. How to use it I'm going to explain later.
The part list:
The wiring between optocoupler and stereo jack has to be done so, that the housing (SLEEVE) of the jack is connected to the emitter of the optocoupler. The collector has to be connected to the left-pin, because only this way you can trigger your camera (it works with Canon and Nikon, if you use a different model the pinout may vary). The right-pin is for the focus, but since you only use the manual focus we don't need this pin.
Pin 1 of the optocoupler is the anode (+) and pin 2 is the cathode (-). If you ask why I'm using an optocoupler: "Keeps you from frying your stuff!". The Arduino generates +5V on every output if you use the digitalWrite()-function. This would harm or damage your camera. So you need a switch between the Arduino and the camera. And this switch is here the optocoupler. Of course could one use a relais, but they aren't as fast and cheap as the optocoupler.
The shematic plan shall clear everything out.
The photocell through which the drop is falling is a DIY one. It is very easy to made, you just need two block clamps and the electrical part. The big advantage is that you don't have to solder anything. Afterwards you can arrange them easily, so they face each other.
On the left side you can see the IR-LED, on the right side is the phototransistor. The distance between both is about 10-30mm. That way the LED illuminates the transistor completely.
The drop has to fall on the exact same position every time and, very important, through the photocell. Therefor you need something stable. The best thing is a table. You can mount the photocell on the bottom of a plank in which you drill a hole. To actually make a drop you can use a syringe. More isn't necesarry to start.
It's on GitHub.
The program is built that way that all necesarry parameters are set before you upload the sketch to the Arduino. The are NOT changeable during runtime. The only exclamation is the parameter 'Adjust_Time', which is be set via the serial monitor.
The 4 parameter are:
- Adjust_Time. Is this time zero the camera triggers when the drop hits the waters surface. Due to some delays in the whole setup it's not that precise. The time can be positive or negative and is given in milliseconds.
- Height_Above_Sensor. This is the distance between the sensor and the outlet in mm.
- Height_Under_Sensor. The distance between the sensor and the waters surface is also given in millimeter.
- Enable_Mirror_Lockup. If your camera supports the mirror lockup you should enable it here and on your cam.
If you want to change the Adjust_Time while the program is running just send the time you want to have in milliseconds via the serial monitor to the Arduino.
There is a last parameter I haven't told you about yet. It's the Secure_Range. Here you have to set the sensors sensibility. Just vary the value as long until the sensor recognizes the drop perfectly on every run.
First the Arduino measures the brightness on the IR-LED and sets this as mark. Then, if Mirror_Lockup is true, the camera will be set ready. Only if the LED on the Arduino becomes bright you can let a droplet fall through the sensor.
Questions and comments: deloarts.wordpress.com