LED Light Level measurements
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Posts: 46,084
I have a project where I need to accurately measure the light levels
from a bank of red LED's. The requirements is to(using the reading)
adjust several groups to the same light levels for common camera
illumination levels.
I plan on taking a light level reading using ??? some type of
detector, pass it through a TLC548 8 bit serial A/d converter and
display the results on a serial LCD screen. Similar to gas detect
project in John Iovine's book.
My question is what type of
photo- sensor/detector/resistor/diode/transistor????? would be best
for reading red LED levels. if additional amplifiers are required
please help with that as well.
from a bank of red LED's. The requirements is to(using the reading)
adjust several groups to the same light levels for common camera
illumination levels.
I plan on taking a light level reading using ??? some type of
detector, pass it through a TLC548 8 bit serial A/d converter and
display the results on a serial LCD screen. Similar to gas detect
project in John Iovine's book.
My question is what type of
photo- sensor/detector/resistor/diode/transistor????? would be best
for reading red LED levels. if additional amplifiers are required
please help with that as well.
Comments
use with the Stamp. You can download the data sheet and lots of
application notes directly from Parallax:
http://www.parallaxinc.com/html_files/partners/taos.htm
Another approach is to use a photodiode directly with the RCtime
command. I used that in the earth measurements course:
http://www.emesys.com/EarthM/em4.pdf
"This lesson explains a photodiode as a linear light detector, and
uses it to explore the huge range of light in the environment. The
lesson gets into the math of sensor calibration. The data is logged
into memory, and means are provided to record several data points and
to play them back later."
The same LED could be used as the photodiode, to receive the specific
light wavelength emitted by your array.
-- best regards
Thomas Tracy Allen PhD
electronically monitored ecosystems
http://www.emesystems.com
mailto:tracy@e...
>I have a project where I need to accurately measure the light levels
>from a bank of red LED's. The requirements is to(using the reading)
>adjust several groups to the same light levels for common camera
>illumination levels.
>
>I plan on taking a light level reading using ??? some type of
>detector, pass it through a TLC548 8 bit serial A/d converter and
>display the results on a serial LCD screen. Similar to gas detect
>project in John Iovine's book.
>
>My question is what type of
>photo- sensor/detector/resistor/diode/transistor????? would be best
>for reading red LED levels. if additional amplifiers are required
>please help with that as well.
Any idea where I could find the Taos chip.
Newark, Digikey, Allied don't carry them (no search found on their
websites).
Original Message
From: Tracy Allen [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=YMA3MCgZfv4rmAg_HcdP33e_cr36aw969G4rrnjntjtCTJ7iD-R6zrxHfjZFWwpZuPwTdz74GF74keJBK9Ye]tracy@e...[/url
Sent: Friday, June 28, 2002 8:34 PM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] LED Light Level measurements
The Taos light-to-frequency sensor chips are exceptionally easy to
use with the Stamp. You can download the data sheet and lots of
application notes directly from Parallax:
http://www.parallaxinc.com/html_files/partners/taos.htm
Another approach is to use a photodiode directly with the RCtime
command. I used that in the earth measurements course:
http://www.emesys.com/EarthM/em4.pdf
"This lesson explains a photodiode as a linear light detector, and
uses it to explore the huge range of light in the environment. The
lesson gets into the math of sensor calibration. The data is logged
into memory, and means are provided to record several data points and
to play them back later."
The same LED could be used as the photodiode, to receive the specific
light wavelength emitted by your array.
-- best regards
Thomas Tracy Allen PhD
electronically monitored ecosystems
http://www.emesystems.com
mailto:tracy@e...
>I have a project where I need to accurately measure the light levels
>from a bank of red LED's. The requirements is to(using the reading)
>adjust several groups to the same light levels for common camera
>illumination levels.
>
>I plan on taking a light level reading using ??? some type of
>detector, pass it through a TLC548 8 bit serial A/d converter and
>display the results on a serial LCD screen. Similar to gas detect
>project in John Iovine's book.
>
>My question is what type of
>photo- sensor/detector/resistor/diode/transistor????? would be best
>for reading red LED levels. if additional amplifiers are required
>please help with that as well.
To UNSUBSCRIBE, just send mail to:
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[noparse][[/noparse]Non-text portions of this message have been removed]
<http://www.future-active.com/>
You might have to buy 10.
>Thanks for the info.
>Any idea where I could find the Taos chip.
>Newark, Digikey, Allied don't carry them (no search found on their
>websites).
>
>
Original Message
>From: Tracy Allen [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=qL2_9OyjtToYR6Qtow-ensylvkmNTRcqztSZIGZFmofcmXPpBZeGr0g2UfyLyqEncvS4PKT_o45N2A]tracy@e...[/url
>Sent: Friday, June 28, 2002 8:34 PM
>To: basicstamps@yahoogroups.com
>Subject: Re: [noparse][[/noparse]basicstamps] LED Light Level measurements
>
>The Taos light-to-frequency sensor chips are exceptionally easy to
>use with the Stamp. You can download the data sheet and lots of
>application notes directly from Parallax:
>
> http://www.parallaxinc.com/html_files/partners/taos.htm
>
>Another approach is to use a photodiode directly with the RCtime
>command. I used that in the earth measurements course:
>
> http://www.emesys.com/EarthM/em4.pdf
> "This lesson explains a photodiode as a linear light detector, and
>uses it to explore the huge range of light in the environment. The
>lesson gets into the math of sensor calibration. The data is logged
>into memory, and means are provided to record several data points and
>to play them back later."
>
>The same LED could be used as the photodiode, to receive the specific
>light wavelength emitted by your array.
>
> -- best regards
> Thomas Tracy Allen PhD
> electronically monitored ecosystems
> http://www.emesystems.com
> mailto:tracy@e...
>
>
> >I have a project where I need to accurately measure the light levels
> >from a bank of red LED's. The requirements is to(using the reading)
> >adjust several groups to the same light levels for common camera
> >illumination levels.
> >
> >I plan on taking a light level reading using ??? some type of
> >detector, pass it through a TLC548 8 bit serial A/d converter and
> >display the results on a serial LCD screen. Similar to gas detect
> >project in John Iovine's book.
> >
> >My question is what type of
> >photo- sensor/detector/resistor/diode/transistor????? would be best
> >for reading red LED levels. if additional amplifiers are required
> >please help with that as well.
>from a bank of red LED's. The requirements is to(using the reading)
>adjust several groups to the same light levels for common camera
>illumination levels.
One thing to think about here is how you will collect the light from
the LEDs. If they are being used for illumination to take photos, you
want to locate the sensor at the camera's lens position, and as far
as possible collect light over the same solid angle that the lens is
imaging.
It may also be desirable to use a red filter over the sensor to help
mask out ambient light during the measurement. If you can obtain a
curve showing the wavelengths the target system is sensitive to, this
would help in selecting a filter.
Reg
Original Message
From: Tracy Allen [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=AB9R8ZFYr0dF7CSM8RLnQOfALiXemTCAn58iIoxFBrGw0ibO288wW45wAiqWEnAFiW76mkCz2pb_O5S0]tracy@e...[/url
Sent: Saturday, June 29, 2002 3:29 PM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] LED Light Level measurements
Oh, I thought Parallax carried the TSL230, but I don't see it now. Try FAI:
<http://www.future-active.com/>
You might have to buy 10.
>Thanks for the info.
>Any idea where I could find the Taos chip.
>Newark, Digikey, Allied don't carry them (no search found on their
>websites).
>
>
Original Message
>From: Tracy Allen [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=AB9R8ZFYr0dF7CSM8RLnQOfALiXemTCAn58iIoxFBrGw0ibO288wW45wAiqWEnAFiW76mkCz2pb_O5S0]tracy@e...[/url
>Sent: Friday, June 28, 2002 8:34 PM
>To: basicstamps@yahoogroups.com
>Subject: Re: [noparse][[/noparse]basicstamps] LED Light Level measurements
>
>The Taos light-to-frequency sensor chips are exceptionally easy to
>use with the Stamp. You can download the data sheet and lots of
>application notes directly from Parallax:
>
> http://www.parallaxinc.com/html_files/partners/taos.htm
>
>Another approach is to use a photodiode directly with the RCtime
>command. I used that in the earth measurements course:
>
> http://www.emesys.com/EarthM/em4.pdf
> "This lesson explains a photodiode as a linear light detector, and
>uses it to explore the huge range of light in the environment. The
>lesson gets into the math of sensor calibration. The data is logged
>into memory, and means are provided to record several data points and
>to play them back later."
>
>The same LED could be used as the photodiode, to receive the specific
>light wavelength emitted by your array.
>
> -- best regards
> Thomas Tracy Allen PhD
> electronically monitored ecosystems
> http://www.emesystems.com
> mailto:tracy@e...
>
>
> >I have a project where I need to accurately measure the light levels
> >from a bank of red LED's. The requirements is to(using the reading)
> >adjust several groups to the same light levels for common camera
> >illumination levels.
> >
> >I plan on taking a light level reading using ??? some type of
> >detector, pass it through a TLC548 8 bit serial A/d converter and
> >display the results on a serial LCD screen. Similar to gas detect
> >project in John Iovine's book.
> >
> >My question is what type of
> >photo- sensor/detector/resistor/diode/transistor????? would be best
> >for reading red LED levels. if additional amplifiers are required
> >please help with that as well.
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
[noparse][[/noparse]Non-text portions of this message have been removed]