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Help! Rapid eye movement detector

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alexzzz

New Member
Hi, I'm trying to build a REM detector and I need some help.

The detector consists of an IR diode coupled with a phototransistor (OPB608A) and is placed on a closed eyelid. The idea is that as the eye moves behind the eyelid the amount of IR light reflected back to the phototransistor should vary.

In my current design I am connecting the emmiter side of the output of phototransistor to the adc of an 18x picaxe, and I am failling to clearly detect any eye movement.

My first question is which would be the best way to connect the phototransistor to the picaxe, as I believe I might be doing something wrong here.

This is how I have it connected now:



IR phototransistor
___
5v|-------c / \ e--------------┬---------|200R|-----|10k Pot|------gnd
¦
________¦__________
|adc pin of picaxe 18x |
----------------------

I've used a pot to try and find an optimal sensitivity but had no success.

How would it affect my signal if I connect the resistance and the picaxe to the collector side of the phototransistor?
 

Mikebits

Well-Known Member
Have a look at this link. It should help.
https://www.electro-tech-online.com/custompdfs/2008/10/AN-3005.pdf

I can't imagine anyone being able to sleep with a gizmo attached to their eyes, but your idea is nice. I think the way scientist detect REM sleep in people is with electrodes attached to the head and they detect REM sleep brain patterns.
 

ormo

New Member
Have a look at this link. It should help.
-- link removed due to post limits --

I can't imagine anyone being able to sleep with a gizmo attached to their eyes, but your idea is nice. I think the way scientist detect REM sleep in people is with electrodes attached to the head and they detect REM sleep brain patterns.

Mikebits is correct, doctors detect REM sleep patterns. I know because I have been subjected to this test before for a video demonstration back in university.
 

alexzzz

New Member
I can't imagine anyone being able to sleep with a gizmo attached to their eyes, but your idea is nice. I think the way scientist detect REM sleep in people is with electrodes attached to the head and they detect REM sleep brain patterns.[/QUOTE]


Ok I believe that is called an Electroencephalography (EEG) and to make one of them would be great. But I don't even know what an electrode is. I'm only a beginner at electronics and I think a REM detector using an IR sensor might be a better first step ... maybe an EEG could be my next project.

So well, mounting the circuit on a sleeping mask comfortable enough to sleep will be the greatest challenge. But Im still stuck on the detecing the eye movement ... As for the link you posted, it seems that my circuit should work although I'm still nor really shore of the difference between the common-emitter and the common-collector.

I'd guess the main problem maybe that I need to adjust the distance and sensitivity of the phototransistor as well as the current in the IR diode.
I have tried this by using a pot on the phototransistor but have not found an effective setting.
 
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