Cadmium Sulfide Flame Sensor

Is there a way I could tie this in with a simple circuit to activate a
series of relays when it senses flame? I am building a small turret
that will first seek brightness (in a dark room, so for example, a
candle) and then when the flame sensor sensor is facing it, activate a
series of relays, some ceasing motion of the 'turret' and one
triggering a pump which will squirt a spray of water in the direction
of the candle or other type of flame. The distance of the flame from
the sensor is required because I want to be able to move the candle
and still have the turret track a different location.

http://www.grainger.com/Grainger/items/1D294?BaseItem=2E360

If possible, I would also like to have the sensor indicate once the
flame is extinguished, and reactivate the turret. This project is
similar to the firefighting robots competition, only the turret is
stationary.

http://www.trincoll.edu/events/robot/

Any and all help is appreciated!

 

[Tim Wescott]

On Tue, 10 Mar 2009 17:17:02 -0700, tranerm wrote:

Is there a way I could tie this in with a simple circuit to activate a
series of relays when it senses flame? I am building a small turret that
will first seek brightness (in a dark room, so for example, a candle)
and then when the flame sensor sensor is facing it, activate a series of
relays, some ceasing motion of the 'turret' and one triggering a pump
which will squirt a spray of water in the direction of the candle or
other type of flame. The distance of the flame from the sensor is
required because I want to be able to move the candle and still have the
turret track a different location.

http://www.grainger.com/Grainger/items/1D294?BaseItem=2E360

If possible, I would also like to have the sensor indicate once the
flame is extinguished, and reactivate the turret. This project is
similar to the firefighting robots competition, only the turret is
stationary.

http://www.trincoll.edu/events/robot/

Any and all help is appreciated!

Yes but.

Yes, you can use some sensors like that.

But they may not be sensitive enough to detect a single candle flame in a
dark room (CdS sensors like that are usually used inside of furnaces,
pointed right at a bright yellow flame less than a foot away).

And CdS sensors are slooooooow.

So you would have to amplify their output, you'd have to use at least two
(to sense the direction to the candle), and you'd have to _really_ slow
your application down.

Why not use a camera and some simple microprocessor signal processor,
instead of 1940's sensors driving 1940's electronics? You can get web
cams these days for a pittance, USB has been around long enough that you
should be able to get an old slow laptop for cheap, and if you don't like
that solution you can get all the bits to build your own camera for
fairly cheap.

--
http://www.wescottdesign.com

 

[Bob Masta]

On Tue, 10 Mar 2009 20:20:59 -0500, Tim Wescott
<tim@seemywebsite.com> wrote:

On Tue, 10 Mar 2009 17:17:02 -0700, tranerm wrote:

Is there a way I could tie this in with a simple circuit to activate a
series of relays when it senses flame? I am building a small turret that
will first seek brightness (in a dark room, so for example, a candle)
and then when the flame sensor sensor is facing it, activate a series of
relays, some ceasing motion of the 'turret' and one triggering a pump
which will squirt a spray of water in the direction of the candle or
other type of flame. The distance of the flame from the sensor is
required because I want to be able to move the candle and still have the
turret track a different location.

http://www.grainger.com/Grainger/items/1D294?BaseItem=2E360

If possible, I would also like to have the sensor indicate once the
flame is extinguished, and reactivate the turret. This project is
similar to the firefighting robots competition, only the turret is
stationary.

http://www.trincoll.edu/events/robot/

Any and all help is appreciated!

Yes but.

Yes, you can use some sensors like that.

But they may not be sensitive enough to detect a single candle flame in a
dark room (CdS sensors like that are usually used inside of furnaces,
pointed right at a bright yellow flame less than a foot away).

And CdS sensors are slooooooow.

So you would have to amplify their output, you'd have to use at least two
(to sense the direction to the candle), and you'd have to _really_ slow
your application down.

Why not use a camera and some simple microprocessor signal processor,
instead of 1940's sensors driving 1940's electronics? You can get web
cams these days for a pittance, USB has been around long enough that you
should be able to get an old slow laptop for cheap, and if you don't like
that solution you can get all the bits to build your own camera for
fairly cheap.

On the other hand, dual CdS sensors could be used
like that old Carl and Jerry episode from Popular
Electronics back in the '60s to track a moving
flashlight. (Boy, am I showing my age!) The idea
was that the right sensor activated the left wheel
of the robot, and the left sensor activated the
right wheel. If the light was straight ahead, the
robot charged straight at it; otherwise, it turned
until both sensors were equally illuminated.

I always wanted to build one of these, but never
got a round to it... <g>

If you just want to move the turret and not the
whole robot, you'd need some logic to stop the
motors when both sensors were equally lit.

Best regards,


Bob Masta

DAQARTA v4.51
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!

 

[ehsjr]

Bob Masta wrote:

On Tue, 10 Mar 2009 20:20:59 -0500, Tim Wescott
tim@seemywebsite.com> wrote:


On Tue, 10 Mar 2009 17:17:02 -0700, tranerm wrote:


Is there a way I could tie this in with a simple circuit to activate a
series of relays when it senses flame? I am building a small turret that
will first seek brightness (in a dark room, so for example, a candle)
and then when the flame sensor sensor is facing it, activate a series of
relays, some ceasing motion of the 'turret' and one triggering a pump
which will squirt a spray of water in the direction of the candle or
other type of flame. The distance of the flame from the sensor is
required because I want to be able to move the candle and still have the
turret track a different location.

http://www.grainger.com/Grainger/items/1D294?BaseItem=2E360

If possible, I would also like to have the sensor indicate once the
flame is extinguished, and reactivate the turret. This project is
similar to the firefighting robots competition, only the turret is
stationary.

http://www.trincoll.edu/events/robot/

Any and all help is appreciated!

Yes but.

Yes, you can use some sensors like that.

But they may not be sensitive enough to detect a single candle flame in a
dark room (CdS sensors like that are usually used inside of furnaces,
pointed right at a bright yellow flame less than a foot away).

And CdS sensors are slooooooow.

So you would have to amplify their output, you'd have to use at least two
(to sense the direction to the candle), and you'd have to _really_ slow
your application down.

Why not use a camera and some simple microprocessor signal processor,
instead of 1940's sensors driving 1940's electronics? You can get web
cams these days for a pittance, USB has been around long enough that you
should be able to get an old slow laptop for cheap, and if you don't like
that solution you can get all the bits to build your own camera for
fairly cheap.



On the other hand, dual CdS sensors could be used
like that old Carl and Jerry episode from Popular
Electronics back in the '60s to track a moving
flashlight. (Boy, am I showing my age!) The idea
was that the right sensor activated the left wheel
of the robot, and the left sensor activated the
right wheel. If the light was straight ahead, the
robot charged straight at it; otherwise, it turned
until both sensors were equally illuminated.

I always wanted to build one of these, but never
got a round to it... <g

* *
* *
* TUIT *
* *
* *

If you just want to move the turret and not the
whole robot, you'd need some logic to stop the
motors when both sensors were equally lit.

Best regards,


Bob Masta

DAQARTA v4.51
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!

 

On Wed, 11 Mar 2009 12:42:21 GMT, N0Spam@daqarta.com (Bob Masta)
wrote:

On Tue, 10 Mar 2009 20:20:59 -0500, Tim Wescott
tim@seemywebsite.com> wrote:

[snip]

On the other hand, dual CdS sensors could be used
like that old Carl and Jerry episode from Popular
Electronics back in the '60s to track a moving
flashlight. (Boy, am I showing my age!) The idea
was that the right sensor activated the left wheel
of the robot, and the left sensor activated the
right wheel. If the light was straight ahead, the
robot charged straight at it; otherwise, it turned
until both sensors were equally illuminated.

I always wanted to build one of these, but never
got a round to it... <g

If you just want to move the turret and not the
whole robot, you'd need some logic to stop the
motors when both sensors were equally lit.

Best regards,


Bob Masta

I remember reading that Carl & Jerry story (among many others) - and
wishing I chad the $ to duplicate it ;-)

I wonder how many others were fascinated with their projects?

John

 

[Sjouke Burry]

tranerm@yahoo.com wrote:

On Mar 10, 6:20 pm, Tim Wescott <t...@seemywebsite.com> wrote:
On Tue, 10 Mar 2009 17:17:02 -0700, tranerm wrote:
Is there a way I could tie this in with a simple circuit to activate a
series of relays when it senses flame? I am building a small turret that
will first seek brightness (in a dark room, so for example, a candle)
and then when the flame sensor sensor is facing it, activate a series of
relays, some ceasing motion of the 'turret' and one triggering a pump
which will squirt a spray of water in the direction of the candle or
other type of flame. The distance of the flame from the sensor is
required because I want to be able to move the candle and still have the
turret track a different location.
http://www.grainger.com/Grainger/items/1D294?BaseItem=2E360
If possible, I would also like to have the sensor indicate once the
flame is extinguished, and reactivate the turret. This project is
similar to the firefighting robots competition, only the turret is
stationary.
http://www.trincoll.edu/events/robot/
Any and all help is appreciated!
Yes but.

Yes, you can use some sensors like that.

But they may not be sensitive enough to detect a single candle flame in a
dark room (CdS sensors like that are usually used inside of furnaces,
pointed right at a bright yellow flame less than a foot away).

And CdS sensors are slooooooow.

So you would have to amplify their output, you'd have to use at least two
(to sense the direction to the candle), and you'd have to _really_ slow
your application down.

Why not use a camera and some simple microprocessor signal processor,
instead of 1940's sensors driving 1940's electronics? You can get web
cams these days for a pittance, USB has been around long enough that you
should be able to get an old slow laptop for cheap, and if you don't like
that solution you can get all the bits to build your own camera for
fairly cheap.

--http://www.wescottdesign.com

Oh well...
I had thought that they sensed flame based on heat, not light. I had
previously sonsidered using an IR sensor to detect the flame but was
informed at how difficult it would be to accurately detect flame, and
how expensive it would get. ):
Do you have any alternative suggestions to detect the flame? I had
planned on using light sensors I have salvaged to run two sets of
motors. One controlling X axis movement and the other Y. So basically
all I need is something that can detect a flame fairly close to
directly ahead of it...but a range of more than a foot would be
nice...thanks for all previous and future submissions!
If you have access to OLD broken? cd players, they have interesting

photosensors.
I have found one with ~8 mm (1/3 inch) four quadrant cell, and if you
put a badly focushed picture of the flame on it, and put differential
amplifiers between the horizontal pair and the vertical pair,
you can sense the direction of the flame in two dimensions.

Use a piece if infrared filter from a broken remote control, to stop
visible light.

 

On Mar 10, 6:20 pm, Tim Wescott <t...@seemywebsite.com> wrote:

On Tue, 10 Mar 2009 17:17:02 -0700, tranerm wrote:
Is there a way I could tie this in with a simple circuit to activate a
series of relays when it senses flame? I am building a small turret that
will first seek brightness (in a dark room, so for example, a candle)
and then when the flame sensor sensor is facing it, activate a series of
relays, some ceasing motion of the 'turret' and one triggering a pump
which will squirt a spray of water in the direction of the candle or
other type of flame. The distance of the flame from the sensor is
required because I want to be able to move the candle and still have the
turret track a different location.

http://www.grainger.com/Grainger/items/1D294?BaseItem=2E360

If possible, I would also like to have the sensor indicate once the
flame is extinguished, and reactivate the turret. This project is
similar to the firefighting robots competition, only the turret is
stationary.

http://www.trincoll.edu/events/robot/

 Any and all help is appreciated!

Yes but.

Yes, you can use some sensors like that.

But they may not be sensitive enough to detect a single candle flame in a
dark room (CdS sensors like that are usually used inside of furnaces,
pointed right at a bright yellow flame less than a foot away).

And CdS sensors are slooooooow.

So you would have to amplify their output, you'd have to use at least two
(to sense the direction to the candle), and you'd have to _really_ slow
your application down.

Why not use a camera and some simple microprocessor signal processor,
instead of 1940's sensors driving 1940's electronics?  You can get web
cams these days for a pittance, USB has been around long enough that you
should be able to get an old slow laptop for cheap, and if you don't like
that solution you can get all the bits to build your own camera for
fairly cheap.

--http://www.wescottdesign.com

Oh well...
I had thought that they sensed flame based on heat, not light. I had
previously sonsidered using an IR sensor to detect the flame but was
informed at how difficult it would be to accurately detect flame, and
how expensive it would get. ):
Do you have any alternative suggestions to detect the flame? I had
planned on using light sensors I have salvaged to run two sets of
motors. One controlling X axis movement and the other Y. So basically
all I need is something that can detect a flame fairly close to
directly ahead of it...but a range of more than a foot would be
nice...thanks for all previous and future submissions!

 

[Frnak McKenney]

On Thu, 19 Mar 2009 18:43:11 -0700 (PDT), tranerm@yahoo.com <tranerm@yahoo.com> wrote:

On Mar 10, 6:20 pm, Tim Wescott <t...@seemywebsite.com> wrote:
On Tue, 10 Mar 2009 17:17:02 -0700, tranerm wrote:
Is there a way I could tie this in with a simple circuit to activate a
series of relays when it senses flame?
--snip--
If possible, I would also like to have the sensor indicate once the
flame is extinguished, and reactivate the turret. This project is
similar to the firefighting robots competition, only the turret is
stationary.

http://www.trincoll.edu/events/robot/
--snip--
Do you have any alternative suggestions to detect the flame? I had
planned on using light sensors I have salvaged to run two sets of
motors. One controlling X axis movement and the other Y. So basically
all I need is something that can detect a flame fairly close to
directly ahead of it...but a range of more than a foot would be
nice...thanks for all previous and future submissions!

One place to start would be browsing the archives of the
comp.robotics.misc newsgroup. I seem to recall the use of UV sensors
to distinguish "flame" from "light", but I don't remember the exact
details.

If you'd like a rapid-acting non-contact thermal (IR) sensor, check
out the Melexis MLX90614 from:

Melexis Microelectronic Systems
http://www.melexis.com/

If you think that the MLX90614 would be useful, you can purchase a
serial-interface module from Parallax:

Parallax
http://www.parallax.com/

Hope this helps.


Frank McKenney
--
To invent, you need a good imagination and a pile of junk.
-- Thomas Alva Edison
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut mined spring dawt cahm (y'all)

 

[Don Klipstein]

In article <49c2fe2c$0$6682$703f8584@textnews.kpn.nl>, Sjouke Burry wrote:

tranerm@yahoo.com wrote:
On Mar 10, 6:20 pm, Tim Wescott <t...@seemywebsite.com> wrote:
On Tue, 10 Mar 2009 17:17:02 -0700, tranerm wrote:
Is there a way I could tie this in with a simple circuit to activate a
series of relays when it senses flame? I am building a small turret that
will first seek brightness (in a dark room, so for example, a candle)
and then when the flame sensor sensor is facing it, activate a series of
relays, some ceasing motion of the 'turret' and one triggering a pump
which will squirt a spray of water in the direction of the candle or
other type of flame. The distance of the flame from the sensor is
required because I want to be able to move the candle and still have the
turret track a different location.
http://www.grainger.com/Grainger/items/1D294?BaseItem=2E360
If possible, I would also like to have the sensor indicate once the
flame is extinguished, and reactivate the turret. This project is
similar to the firefighting robots competition, only the turret is
stationary.
http://www.trincoll.edu/events/robot/
Any and all help is appreciated!
Yes but.

Yes, you can use some sensors like that.

But they may not be sensitive enough to detect a single candle flame in a
dark room (CdS sensors like that are usually used inside of furnaces,
pointed right at a bright yellow flame less than a foot away).

And CdS sensors are slooooooow.

So you would have to amplify their output, you'd have to use at least two
(to sense the direction to the candle), and you'd have to _really_ slow
your application down.

Why not use a camera and some simple microprocessor signal processor,
instead of 1940's sensors driving 1940's electronics? You can get web
cams these days for a pittance, USB has been around long enough that you
should be able to get an old slow laptop for cheap, and if you don't like
that solution you can get all the bits to build your own camera for
fairly cheap.

--http://www.wescottdesign.com

Oh well...
I had thought that they sensed flame based on heat, not light. I had
previously sonsidered using an IR sensor to detect the flame but was
informed at how difficult it would be to accurately detect flame, and
how expensive it would get. ):
Do you have any alternative suggestions to detect the flame? I had
planned on using light sensors I have salvaged to run two sets of
motors. One controlling X axis movement and the other Y. So basically
all I need is something that can detect a flame fairly close to
directly ahead of it...but a range of more than a foot would be
nice...thanks for all previous and future submissions!
If you have access to OLD broken? cd players, they have interesting
photosensors.
I have found one with ~8 mm (1/3 inch) four quadrant cell, and if you
put a badly focushed picture of the flame on it, and put differential
amplifiers between the horizontal pair and the vertical pair,
you can sense the direction of the flame in two dimensions.

Use a piece if infrared filter from a broken remote control, to stop
visible light.

A combo of red and green acrylic / "plexiglas" sheets passes most IR
that silicon photosensors sense, and blocks visible rather well.

Keep in mind that a yellow flame has ratio of IR to visible merely an
order of magnitude (or somewhat less) above that of incandescent lighting
and incandescent flashlights. Also consider that sunlight and daylight
have a significant amount of such infrared, especially direct sunlight.

Do not plan on achieving something that reliably hoses candles and
reliably does not hose incandescent flashlights with an engineering effort
short of or possibly even comparable to "college/university
engineering-major senior design project", which is something done by a
group rather than by an individual.

- Don Klipstein (don@misty.com)

 

[Don Klipstein]

In article <daKdnYqMb4-vFF7UnZ2dnUVZ_o-WnZ2d@earthlink.com>, Frnak
McKenney wrote:

On Thu, 19 Mar 2009 18:43:11 -0700 (PDT), tranerm@yahoo.com
tranerm@yahoo.com> wrote:
On Mar 10, 6:20 pm, Tim Wescott <t...@seemywebsite.com> wrote:
On Tue, 10 Mar 2009 17:17:02 -0700, tranerm wrote:
Is there a way I could tie this in with a simple circuit to activate a
series of relays when it senses flame?
--snip--
If possible, I would also like to have the sensor indicate once the
flame is extinguished, and reactivate the turret. This project is
similar to the firefighting robots competition, only the turret is
stationary.

http://www.trincoll.edu/events/robot/
--snip--
Do you have any alternative suggestions to detect the flame? I had
planned on using light sensors I have salvaged to run two sets of
motors. One controlling X axis movement and the other Y. So basically
all I need is something that can detect a flame fairly close to
directly ahead of it...but a range of more than a foot would be
nice...thanks for all previous and future submissions!

One place to start would be browsing the archives of the
comp.robotics.misc newsgroup. I seem to recall the use of UV sensors
to distinguish "flame" from "light", but I don't remember the exact
details.

There are flame detectors that sense 310 nanometer UV, which is a UVB
wavelength close to borderline UVA, that blue flames produce weakly.
Small flames usually have a blue region producing some of this wavelength.

Keep in mind that this wavelength is only weakly produced by flames, and
flame sensors based on this wavelength assume lack of this wavelength from
normal light sources. However, many fluorescent lamps can produce enough
of this wavelength (even when not to an extent problematic to humans) to
confuse flame sensors based on this wavelength. A few incandescents,
especially some halogens, can do likewise. Daylight also usually has
enough of this wavelength to trigger flame sensors based on this
wavelength.
There are common filters to block this wavelength from "legitimate light
sources" to allow such light sources to be used where flame sensors using
this wavelength are used, including most polycarbonate plastic sheet
materials such as "lexan".

There are also flame sensors based on a very deep UV wavelength of
hydrogen, 121.6 nm - which is a "vacuum UV" wavelength that does not get
through air well (nor most other tyranmsparent materials). It works as a
detector of flames, preferably blue flame such as flame bases, only in
very close proximity. This wavelength is only very weakly emitted by blue
flames, and flame detectors based on this wavelength assume lack of such
wavelength from other sources. Sensors for this wavelength may also
detect radioactivity and X-rays.

If you'd like a rapid-acting non-contact thermal (IR) sensor,

Please keep in mind that many, probably most yellow flames are far
short of "full thermal radiators".

I just tried my "Raytek" non-contact thermometer on a 6 inch diameter
pan with a shallow layer of 91% isopropyl alcohol ignited by a He-Ne laser
power supply. The fire was merely somewhat small and just a little on
the dim side for a fireplace, and the flames had temperature readings
almost entirely less than 150 degrees C, mostly less than 90 degrees C.

check out the Melexis MLX90614 from:

Melexis Microelectronic Systems
http://www.melexis.com/

If you think that the MLX90614 would be useful, you can purchase a
serial-interface module from Parallax:

Parallax http://www.parallax.com/

- Don Klipstein (don@misty.com)

 

[Frnak McKenney]

Don,

Thanks for the feedback.

On Sun, 22 Mar 2009 23:10:54 +0000 (UTC), Don Klipstein <don@manx.misty.com> wrote:

In article <daKdnYqMb4-vFF7UnZ2dnUVZ_o-WnZ2d@earthlink.com>, Frnak
McKenney wrote:

On Thu, 19 Mar 2009 18:43:11 -0700 (PDT), tranerm@yahoo.com
tranerm@yahoo.com> wrote:
On Mar 10, 6:20 pm, Tim Wescott <t...@seemywebsite.com> wrote:
On Tue, 10 Mar 2009 17:17:02 -0700, tranerm wrote:
Is there a way I could tie this in with a simple circuit to activate a
series of relays when it senses flame?
--snip--
... So basically
all I need is something that can detect a flame fairly close to
directly ahead of it...but a range of more than a foot would be
nice...thanks for all previous and future submissions!

One place to start would be browsing the archives of the
comp.robotics.misc newsgroup. I seem to recall the use of UV sensors
to distinguish "flame" from "light", but I don't remember the exact
details.

There are flame detectors that sense 310 nanometer UV, which is
a UVB wavelength close to borderline UVA, that blue flames produce
weakly. Small flames usually have a blue region producing some of
this wavelength.

Hm. On re-reading, it seems that the OP's exact words were "candle
or other type of flame". I got sidetracked by the reference to the
Trinity Firefighting contests.

Keep in mind that this wavelength is only weakly produced by
flames, and flame sensors based on this wavelength assume lack of
this wavelength from normal light sources. However, many
fluorescent lamps can produce enough of this wavelength (even when
not to an extent problematic to humans) to confuse flame sensors
based on this wavelength. A few incandescents, especially some
halogens, can do likewise. Daylight also usually has enough of this
wavelength to trigger flame sensors based on this wavelength.

Ouch. Daylight and incandescents produce all sorts of wavelengths.
I remember watching my carefully-crafted IR-interrupter wheel
encoders become erratic and then fail completely the first time they
hit direct sunlight.

There are common filters to block this wavelength from
"legitimate light sources" to allow such light sources to be used
where flame sensors using this wavelength are used, including most
polycarbonate plastic sheet materials such as "lexan".

I had to re-read this a few times before I realized what you were
referring to: you can use such a sensor to detect flames, but only
if you make sure the environment doesn't have any stray 310nm UV.
And if people complain about stumbling around in the dark (silly
creatures <grin!&gt, well, you have to make sure none of the
squirtgun-triggering wavelengths accompany the room lighting.

Wouldn't work for Trinity, of course. Too uncontrolled.

There are also flame sensors based on a very deep UV wavelength
of hydrogen, 121.6 nm - which is a "vacuum UV" wavelength that does
not get through air well (nor most other tyranmsparent materials).
It works as a detector of flames, preferably blue flame such as
flame bases, only in very close proximity. This wavelength is only
very weakly emitted by blue flames, and flame detectors based on
this wavelength assume lack of such wavelength from other sources.
Sensors for this wavelength may also detect radioactivity and
X-rays.

S'funny. You get into the habit of thinking the human eye is the
only wideband optical sensor, and it catches you by surprise when
you run across another.

If you'd like a rapid-acting non-contact thermal (IR) sensor,

Please keep in mind that many, probably most yellow flames are far
short of "full thermal radiators".

I just tried my "Raytek" non-contact thermometer on a 6 inch
diameter pan with a shallow layer of 91% isopropyl alcohol ignited
by a He-Ne laser power supply. The fire was merely somewhat small
and just a little on the dim side for a fireplace, and the flames
had temperature readings almost entirely less than 150 degrees C,
mostly less than 90 degrees C.

Your flames sounded like they might be a lot bluer than a candle's
(I was still thinking Trinity), so ran my own tests using a
MicroTech MT100 (pocket-sized, 8:1 dispersion):

Birthday candle at 1" 117-178degF
Birthday candle at 2" 77-93degF
Open mouth at 1" 89degF

So... more light than heat. And definitely not much help if you want
to detect the flame before it melts your sensor. <grin!>

Then I re-(re-)read your words abuot "full thermal radiators" and
went back and ran another test. This time I held a table knife
about 1/8" over the candle flame

Soot-covered table knife at 1" "Hi"
Soot-covered table knife at 4" 103degF

In other words, the OP can use a noncontact thermometer as a flame
detector as long as he first places a more effective radiator over
the flame... which shouldn't be too hard, once he has located it.
<grin!>

Which leaves... what? You've described a UV sensor for controlled
environments, but what characteristics of a flame could we use in a
(relatively) uncontrolled space? Firefighting isn't the only
application I can think of that could use such a sensor; what about
(say) placing welding rod within an arc, or guiding a piece of glass
into the center of a bunsen burner flame?

I could believe that a given flame had a unique IR-visible-UV
spectrum, but that might be hard to obtain quickly, and you really
want to classify "flame" vs. "non-flame", not scan a list of umpteen
thousand spectra to see if you get a match.

How about variability? A candle flame certainly varies in color and
intensity, and combustion doesn't take place at lightspeed, so maybe
there are intensity or spectral changes that could be used.

Oh, well. We're pretty well eliminated the Melexis MLX90614 and
friends; I guess that's anough accomplishment for a Monday morning.

Interesting bit of trivia: a "birthday candle" fits nicely between
the tines of an ordinary table fork. This is very handy to know for
those rare cases when no birthday cake is available.

Thanks again, Don.


Frank
--
...the fact that some geniuses were laughed at does not imply
that all who are laughed at are geniuses. They laughed at
Columbus, they laughed at Fulton, they laughed at the Wright
Brothers. But they also laughed at Bozo the Clown.
-- Carl Sagan
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut mined spring dawt cahm (y'all)