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From: Charlie E. on 26 Apr 2010 18:07
Hi All,
You have given me good advice in the past, and I am now really close
to shipping this thing, but still running into some of the same old
problems.

Basically, when I program a unit, it works great here on the bench,
and around the house, but when I go out into the real world, all heck
breaks loose!

My present problems seem to revolve around dark colors. Browns shift
to dark red, or green, blacks suddenly become dark greens, dark denims
become black, dark green, or even dark blue-green.

Trying to determine the cause is difficult, because the problems never
happen in the lab when I am in debug, and can get full data on what is
going on internally. My present guesses all point to shifts in the
strengths of the LEDs and other electronics, perhaps with temperature,
or maybe with differences in background lighting leaking into the
unit.

So, can anyone offer any suggestions? You can find a schematic and a
photo of the unit at
http://edmondsonengineering.com/RainbowColorReader.aspx

Thanks in advance!

Charlie
From: Jim Thompson on 26 Apr 2010 18:28
On Mon, 26 Apr 2010 15:07:02 -0700, Charlie E. <edmondson(a)ieee.org>
wrote:

>Hi All,
>You have given me good advice in the past, and I am now really close
>to shipping this thing, but still running into some of the same old
>problems.
>
>Basically, when I program a unit, it works great here on the bench,
>and around the house, but when I go out into the real world, all heck
>breaks loose!
>
>My present problems seem to revolve around dark colors. Browns shift
>to dark red, or green, blacks suddenly become dark greens, dark denims
>become black, dark green, or even dark blue-green.
>
>Trying to determine the cause is difficult, because the problems never
>happen in the lab when I am in debug, and can get full data on what is
>going on internally. My present guesses all point to shifts in the
>strengths of the LEDs and other electronics, perhaps with temperature,
>or maybe with differences in background lighting leaking into the
>unit.
>
>So, can anyone offer any suggestions? You can find a schematic and a
>photo of the unit at
>http://edmondsonengineering.com/RainbowColorReader.aspx
>
>Thanks in advance!
>
>Charlie

Lab has controlled background ambient? Real world does not.

PIC in an analog circuit :-)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

The only thing bipartisan in this country is hypocrisy
From: Joerg on 26 Apr 2010 19:13
Charlie E. wrote:
> Hi All,
> You have given me good advice in the past, and I am now really close
> to shipping this thing, but still running into some of the same old
> problems.
>
> Basically, when I program a unit, it works great here on the bench,
> and around the house, but when I go out into the real world, all heck
> breaks loose!
>
> My present problems seem to revolve around dark colors. Browns shift
> to dark red, or green, blacks suddenly become dark greens, dark denims
> become black, dark green, or even dark blue-green.
>
> Trying to determine the cause is difficult, because the problems never
> happen in the lab when I am in debug, and can get full data on what is
> going on internally. My present guesses all point to shifts in the
> strengths of the LEDs and other electronics, perhaps with temperature,
> or maybe with differences in background lighting leaking into the
> unit.
>
> So, can anyone offer any suggestions? You can find a schematic and a
> photo of the unit at
> http://edmondsonengineering.com/RainbowColorReader.aspx
>

As Jim hinted you might have background light get in. Since there is
only one phototransistor and not three with suitable filters the unit
can't predetermined the ambient light energies per band. At night you
may also see errors due to mercury vapor street lighting and so on,
worst case also some PWM modulated stuff.

This will be worse with darker colors because the signal to noise ratio
is lower.

BTW, "rainbow" can mean something entirely different in places like San
Francisco :-)

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: John Larkin on 26 Apr 2010 19:14
On Mon, 26 Apr 2010 15:07:02 -0700, Charlie E. <edmondson(a)ieee.org>
wrote:

>Hi All,
>You have given me good advice in the past, and I am now really close
>to shipping this thing, but still running into some of the same old
>problems.
>
>Basically, when I program a unit, it works great here on the bench,
>and around the house, but when I go out into the real world, all heck
>breaks loose!
>
>My present problems seem to revolve around dark colors. Browns shift
>to dark red, or green, blacks suddenly become dark greens, dark denims
>become black, dark green, or even dark blue-green.
>
>Trying to determine the cause is difficult, because the problems never
>happen in the lab when I am in debug, and can get full data on what is
>going on internally. My present guesses all point to shifts in the
>strengths of the LEDs and other electronics, perhaps with temperature,
>or maybe with differences in background lighting leaking into the
>unit.
>
>So, can anyone offer any suggestions? You can find a schematic and a
>photo of the unit at
>http://edmondsonengineering.com/RainbowColorReader.aspx
>
>Thanks in advance!
>
>Charlie


Why is VCC connected to both power pins of U2?

The + input of U2C has no DC path.

What's going on with U8/U9/U10, especially U10?

John


From: Charlie E. on 26 Apr 2010 19:36
On Mon, 26 Apr 2010 15:28:55 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote:

>On Mon, 26 Apr 2010 15:07:02 -0700, Charlie E. <edmondson(a)ieee.org>
>wrote:
>
>>Hi All,
>>You have given me good advice in the past, and I am now really close
>>to shipping this thing, but still running into some of the same old
>>problems.
>>
>>Basically, when I program a unit, it works great here on the bench,
>>and around the house, but when I go out into the real world, all heck
>>breaks loose!
>>
>>My present problems seem to revolve around dark colors. Browns shift
>>to dark red, or green, blacks suddenly become dark greens, dark denims
>>become black, dark green, or even dark blue-green.
>>
>>Trying to determine the cause is difficult, because the problems never
>>happen in the lab when I am in debug, and can get full data on what is
>>going on internally. My present guesses all point to shifts in the
>>strengths of the LEDs and other electronics, perhaps with temperature,
>>or maybe with differences in background lighting leaking into the
>>unit.
>>
>>So, can anyone offer any suggestions? You can find a schematic and a
>>photo of the unit at
>>http://edmondsonengineering.com/RainbowColorReader.aspx
>>
>>Thanks in advance!
>>
>>Charlie
>
>Lab has controlled background ambient? Real world does not.
>
>PIC in an analog circuit :-)
>
> ...Jim Thompson

It IS a PIc in an analog circuit! ;-)

Charlie
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Prev: Financial Management Theory & Practice by Eugene F. Brigham, Michael C. Ehrhardt 13th Edition 2011 Solution manual is available for purchase at affordable prices. Contact me at alltestbanks11[at]gmail.com to buy it today. All emails will be answer
Next: Any insight for Automotive Sensor Inputs/ Front-End Protection.