The candle will be lit up for a while b4 the robot finds it, the height of the candle is not something I will be concerned of......how does a thermocouple works? Is there any new sites where I can learn bout it? I was thinking of using IR sensors or phototransistors/ photodiodes...

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Desperately in need!

 

Then in this case even Sensitive Infrared Photodiode will also work. Use high-gain operational amplifier configuration to amplify photodiode signals and you'll be able to detect the presence of flame. The threshold should be kept at higher voltages so that the circuit won't be triggered by human body temperature or other low heat objects.
This circuit can detect heat from quite long distance.

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"There is no way to peace, peace is the way!"

 

There you go. Posting your intentions will always make a better answer, I hope ppl will read this thread of an example of how you all can specify your questions a little bit further.

I doubt your projects are so secret you can't tell us about it anyway.

No offense, it's far only you that makes this mistake, best of luck with the robot, really cool project!

Cheers
Albert "thec" Sandberg

 

Guys, I was thinking to be a little bit independent by asking bout the parts rather than asking bout the robot...well, seems I've got it all wrong...thanks a lot for everything...

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Desperately in need!

 

Well, what I mean, if you ask "I wan't to make a fire sensitive device", we won't be able to fetch out the same information as if you should have written "I'm building hobby robots for spare time, I wan't to make it to detect fire from other robots". See?

I'm not pushing you down here, just give you directions for faster and more accurate responses, best of luck with your robot!

//Albert "thec" Sandberg

 

May I know wat is the flame's fequency? I mean I need to know that to choose an IR Receiver Module....

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Desperately in need!

 

You actually don't require to know the flame frequency. Any 2-pin photo-diode without any kind of demodulator can sense flame. Try using photodiodes like PD600 or similar which are very sensitive and has inbuilt signal amplifier.
Do not make use of specialized IR receivers like TSOP1738 or any ot TSOP series. These are meant for receiving modulated IR light.

__________________
"There is no way to peace, peace is the way!"

 

PD600 has built in amplifiers? and is PN168 a phototransistor? Can I use a phototransistor instead of a photodiode?

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Desperately in need!

 

You can very well use a photo-transistor.

__________________
"There is no way to peace, peace is the way!"

 

u know that's very funny.....
u made all these people here have a long talk, and then at the end u "pulled the switch"...
so if i understand u need to build a small model robot for firefighting with something like when it "sees" the candle it will splash water?
that means that the termistor, the termocouple versions will not work beacuse the sensors must be in very close range..am i right?
so i would go for the ir sensor, the easyest method....but still a good flash light would trich it, also if u use it outside and if it's sunny......
so as i said my go is for ir

 

bogdanfirst, you are right about the thermistors, or any thing like that. You need a good range of less than 4 inches from my experience. But maybe thats just the cheap ones. Go Infrared.

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\"If Noah had been truly wise, he would have swatted those two flies\" Joe Blaschka

 

Hey guys, I bought a phototransistor but I have no idea how to use it as it has 4 'legs' (I don't know what it's called, maybe Terminals?)
I don't have the data sheet for the component and on the phototransistor there is only one line of wordings :" Heimann 526" Any idea where can I find help?

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Desperately in need!

 

I would say try a general search on any search engine for it. I didn't have any luck, but maybe you will. Also, when you bought it, did it have any other letters or numbers on the package?

__________________
\"If Noah had been truly wise, he would have swatted those two flies\" Joe Blaschka

 

the only problem i can think of with using an ir sensor or phototransistor to detect the flame at a distance is accuracy. most of the ir sensors i have seen are wide angle ones and so would not be able to target whatever you’re using to spray the water that accurately, and also may be triggered by other sources (like nearby incandescent lights).

in addition to setting the voltage threshold high you might want to make a receiving horn for the sensor. it’s pretty simple and just involves taking a piece of flexible plastic, spraying one side with metallic silver paint (or covering with tinfoil shiny side out if you can get a really smooth fit) and rolling it into a narrow cone with the sensor at the small end and the reflective surface on the inside. that way you can increase the accuracy that your robot can pinpoint a source, and also increase the range slightly by sacrificing its field of vision (which can be compensated for by making the robot turn full circle whilst ‘patrolling’ for a fire)

note: silver paint isn't a brilliant reflector of ir radiation, but you can't get much better than the shiny side of ordinatry tinfoil

also, have you considered using a silicon thermopile instead or a generic ir sensor? they tend to be much more accurate and with appropriate use of comparators you can get them to distinguish between body heat, lightbulbs and fires and act accordingly.

(i also tried searching for the phototransistor on various search engines and found nothing. did the shop/catalog you bought it from have any additional info about the item, as this normally inculdes pinouts or examples of usage)

 

u know, i posted my message a little bit much more time before it appeared , so ......just after he said about the robot.....i dont know why it appeared so late.....hm////
i ll go on ir, i built something like this some time ago, but the sensing conditiones where different.... :shock: