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Electronics => Electronics => Topic started by: hendrachubby on June 19, 2009, 06:40:36 AM

Title: Smoke Sensor
Post by: hendrachubby on June 19, 2009, 06:40:36 AM

Anyone can recommend me a sensor to detect smoke intensity ?

Title: Re: Smoke Sensor
Post by: galannthegreat on June 19, 2009, 11:35:11 AM

If the idea of using a smoke detector is in your mind, don't do it, it has a radioactive element inside of it (Americium). Now my suggestion would be looking at optical methods, such as this http://en.wikipedia.org/wiki/Smoke_detector (http://en.wikipedia.org/wiki/Smoke_detector).

Hope this helps! ;D

Title: Re: Smoke Sensor
Post by: Admin on June 19, 2009, 04:18:09 PM

Hack a smoke alarm: Wire the buzzer pin to your microcontroller. Done. ;D

(or any other pin that does binary and not PWM, just use your multimeter to check)

Title: Re: Smoke Sensor
Post by: hendrachubby on June 19, 2009, 04:26:46 PM

can i use combination of photodiode and LED ?

Title: Re: Smoke Sensor
Post by: Admin on June 19, 2009, 04:57:39 PM

Quote from: hendrachubby on June 19, 2009, 04:26:46 PM

can i use combination of photodiode and LED ?

tell us more about the environment, distance away, type of smoke, etc

Title: Re: Smoke Sensor
Post by: HDL_CinC_Dragon on June 19, 2009, 09:48:01 PM

Where there is smoke their is heat. What temperature range will your circuit be exposed to?

Title: Re: Smoke Sensor
Post by: hendrachubby on June 20, 2009, 06:35:37 AM

i want to measure cigarette smoke thickness, because i got a research about thermoforesist filter..so i must measure the smoke intensity before and after the filter...i've tried using combination of led and photodiode, but the voltage deviation is small...any idea ?

Title: Re: Smoke Sensor
Post by: awally88 on June 20, 2009, 07:01:32 AM

Try using an Op Amp to amplify the voltage that you get from the photoresitor.

Title: Re: Smoke Sensor
Post by: Soeren on June 20, 2009, 08:58:55 AM

Hi,

You could buy a cheap fire alarm (make sure it's got an optical detector - the package will tell, but they are the usual type sold cheap - $4 to $8 should get you one), it has got a matched pair of IR LED and IR photo diode that you can harvest and you'll see how it is mounted.

Here is one I dismantled to use the detector for automatic opening of windows on "poker nights"
(http://That.Homepage.dk/Img/Optical_Smoke_Detector.jpg)
http://That.Homepage.dk/Img/Optical_Smoke_Detector.jpg (http://That.Homepage.dk/Img/Optical_Smoke_Detector.jpg)

You need to mount the pair in a way so they cannot see each other, but just the light reflected from the smoke particles - use baffles for that.
(http://That.Homepage.dk/Img/Smoke_Intensity.png)
http://That.Homepage.dk/Img/Smoke_Intensity.png (http://That.Homepage.dk/Img/Smoke_Intensity.png)

Make sure the "funnel" covers the entire output of the filter (turn it upside down for the input to the filter).

You'll need to calibrate the outputs to get reliable results of course.

Title: Re: Smoke Sensor
Post by: hendrachubby on June 21, 2009, 01:25:56 AM

Okay, so fire alarm use combination of IR led and IR photodiode...humm that's very helpfull, because i don't know fire alarm use that..thx