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[SOLVED] need help with phototransistor for particle (dust) sensing

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oushiza69

oushiza69

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i`m newbie in electronic world, and i need help with my assigment
i used that kind of circuit for my final project, i used that ir-led+phototransistor circuit for sense a dust particle (pm10 particle category)
42_1301669620.jpg

i want the particle reflect the ir from led when it pass in front of that sensor,i deisgn the sensor like this
63_1301670663.jpg

is it possible for me if i used that circuit and that design??
wheter that circuit can only be used as a switch?? because i need this circuit for measurement with high sensitivity
i need the output from that phototransistor to design driver for that circuit before i connect it to microprocessor
 
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Will you suffer from random (sunlight) IR?. I would fire up your IR emitter with a 2KHz square wave. This way at the other end you are looking for 2KHz and you can filter out all other frequencies and as its AC, the amplifying of it is much easier.
Frank
 
i will put the sensor on box with no sunlight-effect, but it really difficult to measure the output of my phototransistor,what is actually my sensor problem?
is collector-emittor saturation voltage is an output of phototransistor?
 
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I don't exactly understand the intended sensor geometry from your drawing. Generally, dust can be measured optically. If your setup is actually sensitive enough is a different question.

I think scattering is a better measurement method than reflection, a modulated LED current source would allow a suppression of enviromental light and easy amplification of received signal, also short wavelength light can be expected to give a higher sensitivity for fine particles than IR.
 
i`ll try to find another metode to measure dust (especially pm10 particle category),that is with reflection
the hard thing is i can`t measure the output of my phototransistor,is anything wrong with my circuit?
because this is my project for my final assigment,and if can`t solve this problem that is a high probability i can`t finish my education
plese help me with this sensor model
any suggest that can help me finish this problem?
 

i just try to find another metode to measure dust (especially pm10 particle category),that is with reflection
the hard thing is i can`t measure the output of my phototransistor,is anything wrong with my circuit?
because this is my project for my final assigment,and if can`t solve this problem that is a high probability i can`t finish my education
plese help me with this sensor model
any suggest that can help me finish this problem?

---------- Post added at 02:33 ---------- Previous post was at 02:31 ----------
kak111 said:
Some maybe helpful reading...............

http://sharp-world.com/products/device/lineup/data/pdf/datasheet/gp2y1010au_e.pdf

**broken link removed**

**broken link removed**
Click to expand...

thanx for helping,i`ll try to figure it out first,but i`ll come back when i get stuck again T-T

---------- Post added at 02:51 ---------- Previous post was at 02:33 ----------

that is the methode that i try too figure out,the one and only my problems is i can`t measure the output of my phototransistor
thanx for kak111 for helping me
 

The main difference between the Sharp sensor and your circuit is 1. modulation, 2. amplification. Both are required for sufficient sensitivity. The sensor uses 90° scattering configuration.
 
Important points are maximize light intesity and amplifier gain without noise.
Adding some optics helps sensitivity and resolution.
More reading..................

Airborne particle counting
 
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