LED beam breakers

Hi there, I’m new to the world of specialised computing and electronics so please treat me like a total beginner and excuse my ignorance.

I have been advised to use Arduino to get some of my data collection automated. I have never used arduino, or something similar, and don’t even know what to purchase to build the set up. I want two infra red LED beam sources and detectors to attach in the middle of a large petri dish, and appropriate circuitry/software that detects the data and stores on my macbook air.

The idea is that a bee is walking in the petridish for 10 minutes and I want to know the total time it spends on each half, when it breaks each beam and the sequence of beam breaks. Each beam will go across the edge of each half, with a thin strip of ‘no-mans-land’ between the two beams (approx. a bee length wide).

Can someone advise me on all the components and software I need to purchase to set this up? And any advice on installing and setting up the software to collect the data would be much appreciated too.

Thanks a lot

Sparkfun has some IR stuff for ideas. Google searches for similar projects and the forum search in the upper right of this page might produce some useful info.

You could use an array of LDRs,Light Dependent Resistors, under the petridish, with a light above it.
You then have to monitor the LDRs to see which is getting lower light than the rest.

Tom.... :slight_smile:

Why do you propose to use IR?

Is this because you can't see it? Do you think therefore, that the bee can't see it?

If the budget will stretch to it this sounds like an ideal job for a Pixy. It could report the X/Y position of the bee(s) to an arduino/pc and it determines what side of the line a bee is.

How about supporting the petri dish on three points and the support points are sitting on sensitive load cells. The XY location could be determined by the forces measured on each load cell, this is taking a different approach but I think it will work but I have not done the analysis to see what sensitivity is needed for the load cells.

I think it will work but I have not done the analysis to see what sensitivity is needed for the load cells.

They will need to be very sensitive. Once you shave all the hair off a bumblebee is quite skinny. :slight_smile:

Untested but I hope you understand the principle:

Divide the surface under the petri dish into areas (to watch), and put one LDR into each section. Make sure that the sections are lighted only from top, not from side (cartoon strips...), and that a light source above the device will be brighter than ambient light from the sides, or keep ambient light off somehow. The LDRs should cover the area or boundaries to watch, eventually use multiple LDRs in series to cover bigger areas. Connect the LDRs with resistors to Vcc, to form half-bridges (voltage dividers). A light diffusor (thin paper...) over the sections may also be applicable - find out yourself.

An array with the initial (uncovered) LDR voltages may be helpful, so that you can determine later which LDR is actually covered and has increased resistance. In setup() fill the array with the current values, which take into account the current lighting source.

WOW, deja vu, post #2.

Tom.... :slight_smile:
Great minds think alike.
But fools never differ.