about photodiodes.... - Electronic Circuits Projects Diagrams Free

cws5447 · 11th September 2003, 07:53 PM

:? how to use a photodiode to detect candle light??
i'm building a fire fighting like robot...how to get photodiode as the eye for finding candle light?? o anybody has any better suggestion to me....
thank you... :wink:

Klaus · 12th September 2003, 05:50 AM

You'll need more than one diode to detect in which direction your burning candle is perhaps if you arrange them in a pattern you could steer your robot towards the biggest light output from the diodes.
You could get away with a single light sensing diode if you spin it in a horizontal circle and use a computer to interpret the changing light output with reference to a simultaneously rotating anglular position sensor.
Maybe an infrared photodiode might be better to sense fire, there's a lot more heat than visible light output from a candle.

Have fun with that one 8)

Klaus

cws5447 · 12th September 2003, 07:45 AM

okie....but how does the thing work?? i mean do i need a proccessor to proccess the data collected?? i'm using a pic to be my center proccessing unit so i just need i high o low signal from the source finder to my pic only..

z3017105 · 13th September 2003, 07:55 AM

I am also using photodiodes in my project but for a different purpose. I too am unsure how to connect it into my circuit. Firstly, I have read that a photodiode in concept is a current source in shunt with diode. Then I read somewhere else that its actually like a light switch. So I am just a bit confused whether a photodiode requires a power source or it generates current when it detects light.

cws5447 · 14th September 2003, 08:32 PM

how to increase the detecting range for a photodiode??

where a TL017 op is used to get 5v output. :? candle light is to be detect...thank for any suggestion!! :wink:

jacobs_ladder · 14th September 2003, 09:10 PM

When a photon, or light, hits the material in the photo diode, excited electrons are released and create current. Putting a resistance in shunt with the diode will create a voltage in the resistor. But it is best to amplify the output of the diode to something usable by the rest of your circuit.

http://www.centrovision.com/tech2.htm

That site shows some basics about photo diodes and configurations. You may also need thero electric detectors as well. The candle reflections will look exactly like the candle to your robot.

Hope this helps.

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11th September 2003, 07:53 PM	(permalink)
cws5447	about photodiodes.... :? how to use a photodiode to detect candle light?? i'm building a fire fighting like robot...how to get photodiode as the eye for finding candle light?? o anybody has any better suggestion to me.... thank you... :wink: __________________ Success is the ability to go from one failure to another with no loss of enthusiasm - Sir Winston Churchill.

12th September 2003, 05:50 AM	(permalink)
Klaus	You'll need more than one diode to detect in which direction your burning candle is perhaps if you arrange them in a pattern you could steer your robot towards the biggest light output from the diodes. You could get away with a single light sensing diode if you spin it in a horizontal circle and use a computer to interpret the changing light output with reference to a simultaneously rotating anglular position sensor. Maybe an infrared photodiode might be better to sense fire, there's a lot more heat than visible light output from a candle. Have fun with that one 8) Klaus

12th September 2003, 07:45 AM	(permalink)
cws5447	okie....but how does the thing work?? i mean do i need a proccessor to proccess the data collected?? i'm using a pic to be my center proccessing unit so i just need i high o low signal from the source finder to my pic only.. __________________ Success is the ability to go from one failure to another with no loss of enthusiasm - Sir Winston Churchill.

13th September 2003, 07:55 AM	(permalink)
z3017105	I am also using photodiodes in my project but for a different purpose. I too am unsure how to connect it into my circuit. Firstly, I have read that a photodiode in concept is a current source in shunt with diode. Then I read somewhere else that its actually like a light switch. So I am just a bit confused whether a photodiode requires a power source or it generates current when it detects light.

14th September 2003, 08:32 PM	(permalink)
cws5447	increase range how to increase the detecting range for a photodiode?? where a TL017 op is used to get 5v output. :? candle light is to be detect...thank for any suggestion!! :wink: __________________ Success is the ability to go from one failure to another with no loss of enthusiasm - Sir Winston Churchill.

14th September 2003, 09:10 PM	(permalink)
jacobs_ladder	When a photon, or light, hits the material in the photo diode, excited electrons are released and create current. Putting a resistance in shunt with the diode will create a voltage in the resistor. But it is best to amplify the output of the diode to something usable by the rest of your circuit. http://www.centrovision.com/tech2.htm That site shows some basics about photo diodes and configurations. You may also need thero electric detectors as well. The candle reflections will look exactly like the candle to your robot. Hope this helps.