algae pigment extraction

Ross Koning Koning at ECSUC.CTSTATEU.EDU
Wed Jan 17 14:40:47 EST 1996

At 10:15 AM 1/15/96 -0500, FMims wrote:
>Kathleen Arche (Kathleen.Archer at MAIL.CC.TRINCOLL.EDU) asked (in part):
>I have and am currently measuring discrete photosynthetic radiation in the
>blue and red using miniature data loggers under a wide variety of natural
>conditions in Texas, Hawaii and Brazil.
>Forrest M. Mims III
>Sun Photometer Atmospheric Network (SPAN)


I think you are rather famous for some handbooks
on opto-electronic circuits for beginners.  If
so, perhaps you could lead some of us teachers
in how to make two diode arrays as sources of red
or far-red light for projects with phytochrome?

One circuit board (breadboard or some "easy" equivalent)
should be studded with reasonably high-output LEDs
that emit 660 nm light.  The other should have LEDs
that emit 730 nm light.  If possible the output should
be the same.  The array should be able to illuminate
a 10 cm diameter Petri dish.

I have used filters and lamps with very little
actual control on wavelength or intensity.  It seems
to me that diodes should put out fairly narrow-band
light and proper selection of diodes should allow
one to have similar photon flux from the two arrays.

Do you have or could you make up such a schematic?
The key elements would be the supply source for the
diodes (it seems to me) and the nature of the power
supply.  An AC source is more convenient for me, but
sometime I might want to drive the units at a powerless
location on batteries.  A DC circuit with an input
jack and specifications for an AC adapter would be


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 \ Ross Koning                                  \
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