PSN-L Email List Message

Subject: Re: Not so simple photoelectrics
From: "meredith lamb" mlamb1@.........
Date: Sun, 27 May 2001 23:53:00 -0700




ChrisAtUpw@....... wrote:

> I
> Dear Meredith,
>
>       You might like to consider some of the following design ideas:-
>
>       Precision Si photocells have closely matching characteristics in
> terms
> of sensitivity, wavelength response, change of sensitivity with
> illumination,
> change of sensitivity with temperature and reverse leakage current.
> The
> response is fast, free of drift and the photo current is linear with
> illumination. It is not possible to buy CdS cells matched to anything
> like
> this precision. The response is very much slower and may show drift
> over some
> seconds. The CdS response is very non linear with changes in
> illumination
> level and any two cells may be expected to have significantly
> different
> response curves. They are also quite temperature sensitive.

Hi Chris,

I'd suspect that any matched cells would have a very high price
tag, although I've not obtained any prices.  On the cheap side,
is there a way to use only a digital volt-ohm-meter, that perhaps
might yield some "close" characteristics; say from a limited
number of single cells (probably not likely)?  Any brand name
spring to mind that seems to offer more consistency than other
brands?  I have some Centronic P/N OSD15-5T photovoltiac
cells, but I've no idea of their production quality control or standing
among other makers.

Thanks for the reply with all the notes, they all seem quite
instructive...and welcome of course.

Meredith Lamb






 

ChrisAtUpw@....... wrote:

I
Dear Meredith,

      You might like to consider some of the following design ideas:-

      Precision Si photocells have closely matching characteristics in terms
of sensitivity, wavelength response, change of sensitivity with illumination,
change of sensitivity with temperature and reverse leakage current. The
response is fast, free of drift and the photo current is linear with
illumination. It is not possible to buy CdS cells matched to anything like
this precision. The response is very much slower and may show drift over some
seconds. The CdS response is very non linear with changes in illumination
level and any two cells may be expected to have significantly different
response curves. They are also quite temperature sensitive.

Hi Chris,

I'd suspect that any matched cells would have a very high price
tag, although I've not obtained any prices.  On the cheap side,
is there a way to use only a digital volt-ohm-meter, that perhaps
might yield some "close" characteristics; say from a limited
number of single cells (probably not likely)?  Any brand name
spring to mind that seems to offer more consistency than other
brands?  I have some Centronic P/N OSD15-5T photovoltiac
cells, but I've no idea of their production quality control or standing
among other makers.

Thanks for the reply with all the notes, they all seem quite
instructive...and welcome of course.

Meredith Lamb
 
 
 
 


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Larry Cochrane <cochrane@..............>