Naked Science Forum
Non Life Sciences => Technology => Topic started by: BRTYERY on 17/09/2018 12:43:35
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Hello
I have infrared LED how to use it for smoke detector
I have seen there are black and white surface of Infrared led which emit good infrared Light but when i use it with multi meter
digital voltage reader i don't understand how it voltage increase with light falling on it like match box
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You should read this.
https://en.wikipedia.org/wiki/Smoke_detector
In particular with reference to the photoelectric type of detector.
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Hello
There is smoke sensor in it
Which sense the smoke how does it calculate the amount of smoke sense in it
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Enjoy.
https://en.wikipedia.org/wiki/Photodetector
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Hello
There is smoke sensor in it
Which sense the smoke how does it calculate the amount of smoke sense in it
It does not calculate how much smoke.
If there is any (above some threshold) , it sounds the alarm.
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I don't understand how it voltage increase with light falling on LED?
LEDs are mostly used to emit light.
There is a small voltage produced when light of the same wavelength falls on the LED, but normal LEDs are not optimized for this (on the other hand, solar panels are optimised to produce a voltage when light falls on them).
You need to couple a LED (to emit light) with a photodetector (to detect light). The photodetector must be sensitive to the wavelength emitted by the LED.
I have infrared (photodetector) how to use it for smoke detector?
There are several ways you could try to use infra-red; one of them doesn't work:
1. Smoke rises to the ceiling; detect that the light received by the photodetector from the LED is dimmer, and raise an alarm. However, infra-red is not attenuated very much by smoke; you would be better to use a LED and photodetector operating at the green or blue end of the spectrum.
2. Hot objects emit infra-red light into the room. If you detect a lot of infra-red, raise an alarm. But don't try this in a kitchen area, because infra-red emitted by the stove-top will set off your alarm.
3. You could try another device called a thermistor, mounted up near the ceiling. Hot smoke rises, and will change the temperature of the thermistor. Make sure that the threshold is set above the hottest day you are likely to encounter in India.
These approaches would be fine for a school science competition.
In reality, for use in your home or business, commercial smoke detectors are relatively cheap, have been well tested for reliability by Underwriters Laboratories and others, and will make you a lot safer than one you made yourself. How much is your life worth?
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Hello
where to use infrared for vegetable and fruits
can we test them with it
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where to use infrared for vegetable and fruits
There is an app for that:
https://www.smithsonianmag.com/innovation/you-may-soon-be-able-scan-piece-fruit-check-nutritional-value-180958710/
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I will tell from camera pint of view. The appearance of IR LED is same as a common LED. Since the human eye cannot see the infrared radiations, it is not possible for a person to identify if an IR LED is working. A camera on a cell phone camera solves this problem. The IR rays from the IR LED in the circuit are shown in the camera.