Basic chronograph

Projects General Guidance
1

Hi people,
First post here and I'd just like to say Hello. XD
I'm TD_1, I'm currently studying Software engineering at University in the UK

I'm an avid Airsoft'er[R1] and I've found that chronographs for this purpose are in the region of anywhere between £30 and £130 (Dependent on the brand, most are the same internally but its the cost that's off putting.. even if £30 isn't a great deal its still more money than I would like to spend on an item I use once every 3 months for basic testing and maintainance etc

Now my project is to build a simple FPS (Feet Per Second) Chronograph that uses light gates to test the difference between two points. The system will need to take into consideration the weight of the round (varying from .12g - .50g BB's). Being as this is going to be my first real encounter of the Arduino, When writing the application I will be using a Raspberry Pi to run, debug and test my applications..

Now my question is: Would two standard light sensors work for this project? Obviously the sensors would need to be programmed that when the beam is broken it is activated, rather than when the light is detected, it is activated.

my basic idea (Pseudo code) is something like:

int gate_one = 1;
int gate_two = 1;
int start;
int end;
int fps;
int dist = 0.333333;

if (gate_one = 0, gate_two = 1){
 start();
 if(gate_one = 1, gate_two = 0){
 end();
}}
 time = end - start;
fps = dist / time;

printf(fps); //Print to screen, LCD panel etc

obviously my code is very basic and it will be changed as I go but can anyone point me in the direction of the type of sensors I'm looking for?

Thanks!

References:
[R1] Airsoft - Airsoft - Wikipedia

2

I don't know what you had mind for a "standard light sensors" but avoid anything with an LDR, it won't be fast enough.
Look for a photodiode or phototransistor.
You may want to read up on C syntax.

3

AWOL:
I don't know what you had mind for a "standard light sensors" but avoid anything with an LDR, it won't be fast enough.
Look for a photodiode or phototransistor.
You may want to read up on C syntax.

an LDR is pretty much what I had in mind with Standard Light Sensors, however I know Photodiodes are faster than transistors.

and I do know quite alot of C and C++ however while writing my pseudo I failed to see that an int can't have Decimals and should be a float :cold_sweat: however as I've been writing Java all day I just wrote it without any sort of thought!

Is there an emulator I could test my designs on?

4

Hi TangoDelta_1 ...did you finish your project?

Greetings!