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Next: Any insight for Automotive Sensor Inputs/ Front-End Protection.
From: Joerg on 2 May 2010 21:21
Charlie E. wrote:

[...]

> Since I have chosen my illumination source, and RGB LED run one color
> at a time, I am not dealing with different illumination sources. I am
> also not trying to do high accuracy color determination, just red,
> green, blue, orange, etc. My frustration is that two units,
> apparently calibrated identically, will still see certain colors
> differently. Trying to identify the source of the differences led me
> to consult with my friends here to see if there was some electronic
> design error on my part. I suspect that, such little things as
> different alignments of the LED and PT, different arrangements of my
> blocking black felt, and even temperature of the unit may be enough to
> skew the results so that certain 'border' colors change nations, i.e
> beige becomes pink, gold becomes orange, and blue becomes purple, or
> blue green.
>

Did you turn the black level subtraction back on? Also, I think just
some felt inside a thin plastic enclosure isn't going to cut it, you
need at least foil underneath and then make sure that nothing in the
sensor area heats up too much.


> Fortunately, in my market, it appears that this is a conundrum that
> hasn't really been solved yet! Some makers require a calibration
> before every read. I think I may just ship what I have, and see if it
> is useful enough at my price point, to make sales.
>

Understandable but dangerous. At least I would compare it to other units
that are in the market. Serious egg in the face never really wipes off
clean in small markets, people remember. Best not to let that happen.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: JosephKK on 3 May 2010 00:14
On Sun, 02 May 2010 18:21:16 -0700, Joerg <invalid(a)invalid.invalid>
wrote:

>Charlie E. wrote:
>
>[...]
>
>> Since I have chosen my illumination source, and RGB LED run one color
>> at a time, I am not dealing with different illumination sources. I am
>> also not trying to do high accuracy color determination, just red,
>> green, blue, orange, etc. My frustration is that two units,
>> apparently calibrated identically, will still see certain colors
>> differently. Trying to identify the source of the differences led me
>> to consult with my friends here to see if there was some electronic
>> design error on my part. I suspect that, such little things as
>> different alignments of the LED and PT, different arrangements of my
>> blocking black felt, and even temperature of the unit may be enough to
>> skew the results so that certain 'border' colors change nations, i.e
>> beige becomes pink, gold becomes orange, and blue becomes purple, or
>> blue green.
>>
>
>Did you turn the black level subtraction back on? Also, I think just
>some felt inside a thin plastic enclosure isn't going to cut it, you
>need at least foil underneath and then make sure that nothing in the
>sensor area heats up too much.
>
>
>> Fortunately, in my market, it appears that this is a conundrum that
>> hasn't really been solved yet! Some makers require a calibration
>> before every read. I think I may just ship what I have, and see if it
>> is useful enough at my price point, to make sales.
>>
>
>Understandable but dangerous. At least I would compare it to other units
>that are in the market. Serious egg in the face never really wipes off
>clean in small markets, people remember. Best not to let that happen.

Of course some of that is in how it is marketed. If it is sold as right
often enough to be useful that is one thing, if it is marketed as
reliable and repeatable it is another.
From: Joerg on 3 May 2010 10:58
JosephKK wrote:
> On Sun, 02 May 2010 18:21:16 -0700, Joerg <invalid(a)invalid.invalid>
> wrote:
>
>> Charlie E. wrote:
>>

[...]

>>
>>> Fortunately, in my market, it appears that this is a conundrum that
>>> hasn't really been solved yet! Some makers require a calibration
>>> before every read. I think I may just ship what I have, and see if it
>>> is useful enough at my price point, to make sales.
>>>
>> Understandable but dangerous. At least I would compare it to other units
>> that are in the market. Serious egg in the face never really wipes off
>> clean in small markets, people remember. Best not to let that happen.
>
> Of course some of that is in how it is marketed. If it is sold as right
> often enough to be useful that is one thing, if it is marketed as
> reliable and repeatable it is another.


Even in the first case it better be on par with simlarly priced other
units or better. I don't know the market for Charlie's device but it is
amazing how fast reputation is gained or lost with the Internet these
days. All it takes is a major blog somewhere.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: Charlie E. on 3 May 2010 11:12
On Sun, 02 May 2010 18:21:16 -0700, Joerg <invalid(a)invalid.invalid>
wrote:

>Charlie E. wrote:
>
>[...]
>
>> Since I have chosen my illumination source, and RGB LED run one color
>> at a time, I am not dealing with different illumination sources. I am
>> also not trying to do high accuracy color determination, just red,
>> green, blue, orange, etc. My frustration is that two units,
>> apparently calibrated identically, will still see certain colors
>> differently. Trying to identify the source of the differences led me
>> to consult with my friends here to see if there was some electronic
>> design error on my part. I suspect that, such little things as
>> different alignments of the LED and PT, different arrangements of my
>> blocking black felt, and even temperature of the unit may be enough to
>> skew the results so that certain 'border' colors change nations, i.e
>> beige becomes pink, gold becomes orange, and blue becomes purple, or
>> blue green.
>>
>
>Did you turn the black level subtraction back on? Also, I think just
>some felt inside a thin plastic enclosure isn't going to cut it, you
>need at least foil underneath and then make sure that nothing in the
>sensor area heats up too much.
>
>
>> Fortunately, in my market, it appears that this is a conundrum that
>> hasn't really been solved yet! Some makers require a calibration
>> before every read. I think I may just ship what I have, and see if it
>> is useful enough at my price point, to make sales.
>>
>
>Understandable but dangerous. At least I would compare it to other units
>that are in the market. Serious egg in the face never really wipes off
>clean in small markets, people remember. Best not to let that happen.

Hi Jeorge,
Yep, I turned on the black level subtraction (or, increased it to
match temporal conditions...) and it has helped some. Also, sensor is
in front of unit, power supplies are at least an inch away. I am more
concerned with the opamps and the digital pot maybe self heating,
especially when I have been testing for a while...

My real problem I think is engineer's disease... I keep thinking of
improvements to the hardware and software!

Charlie
From: Charlie E. on 3 May 2010 11:13
On Sun, 02 May 2010 21:14:18 -0700,
"JosephKK"<quiettechblue(a)yahoo.com> wrote:

>On Sun, 02 May 2010 18:21:16 -0700, Joerg <invalid(a)invalid.invalid>
>wrote:
>
>>Charlie E. wrote:
>>
>>[...]
>>
>>> Since I have chosen my illumination source, and RGB LED run one color
>>> at a time, I am not dealing with different illumination sources. I am
>>> also not trying to do high accuracy color determination, just red,
>>> green, blue, orange, etc. My frustration is that two units,
>>> apparently calibrated identically, will still see certain colors
>>> differently. Trying to identify the source of the differences led me
>>> to consult with my friends here to see if there was some electronic
>>> design error on my part. I suspect that, such little things as
>>> different alignments of the LED and PT, different arrangements of my
>>> blocking black felt, and even temperature of the unit may be enough to
>>> skew the results so that certain 'border' colors change nations, i.e
>>> beige becomes pink, gold becomes orange, and blue becomes purple, or
>>> blue green.
>>>
>>
>>Did you turn the black level subtraction back on? Also, I think just
>>some felt inside a thin plastic enclosure isn't going to cut it, you
>>need at least foil underneath and then make sure that nothing in the
>>sensor area heats up too much.
>>
>>
>>> Fortunately, in my market, it appears that this is a conundrum that
>>> hasn't really been solved yet! Some makers require a calibration
>>> before every read. I think I may just ship what I have, and see if it
>>> is useful enough at my price point, to make sales.
>>>
>>
>>Understandable but dangerous. At least I would compare it to other units
>>that are in the market. Serious egg in the face never really wipes off
>>clean in small markets, people remember. Best not to let that happen.
>
>Of course some of that is in how it is marketed. If it is sold as right
>often enough to be useful that is one thing, if it is marketed as
>reliable and repeatable it is another.

Exactly. Most of the products out there now in this market are in the
'right enough to be useful' category. What is interesting is some of
the more expensive units, where you could buy a calibrated colorimeter
for less...

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.