root@raider.MFEE.TN.US (Bob Reineri) (04/07/89)
I've recently planted our first garden, and being the computer nut that I am,
love to keep records. The rainfall and temperature are easy enough to get. The
other item I would like to track is the amount of sunlight the garden gets on
a daily basis. I am entering all this into a database so I'll have something
to ponder over the next winter.
Does anyone have any ideas on what might be a suitable circuit for this applic-
ation ? Many moons ago, I was a bench tech, but am now in the software end of
it, and the hardware is somewhat foggy.
I do have one idea: Perhaps a solar cell, connected thru an RC network, that
would charge up a capacitor to a given voltage, depending on the amount of
sunlight received over the course of a day. Then I could somehow measure the
charge on the cap at the end of the day. Just a thought....
Any ideas would be greatly appreciated.
Bob
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*DOMAIN: root@raider.MFEE.TN.US UUCP:!{ames,rutgers,decwrl}!killer!raider*henry@utzoo.uucp (Henry Spencer) (04/09/89)
In article <102@raider.MFEE.TN.US> root@raider.MFEE.TN.US (Bob Reineri) writes: >... Perhaps a solar cell, connected thru an RC network, that >would charge up a capacitor to a given voltage, depending on the amount of >sunlight received over the course of a day. Then I could somehow measure the >charge on the cap at the end of the day. Just a thought.... Capacitor leakage will probably kill you on this. This sort of long-term memory application is where digital circuitry is ideal. Say a 555 set up as a slow (say a tick every 10 minutes) oscillator, enabled by sunlight (via a phototransistor, say), feeding an 8-bit counter. If you want more precision, add some more bits of counter and speed up the oscillator. If you want to measure light intensity, not just duration, use a VCO rather than a fixed-rate oscillator. -- Welcome to Mars! Your | Henry Spencer at U of Toronto Zoology passport and visa, comrade? | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
john@stiatl.UUCP (John DeArmond) (04/09/89)
In article <102@raider.MFEE.TN.US> root@raider.MFEE.TN.US (Bob Reineri) writes: >I've recently planted our first garden, and being the computer nut that I am, >love to keep records. The rainfall and temperature are easy enough to get. The >other item I would like to track is the amount of sunlight the garden gets on >a daily basis. I am entering all this into a database so I'll have something >to ponder over the next winter. > >Does anyone have any ideas on what might be a suitable circuit for this applic- >ation ? Many moons ago, I was a bench tech, but am now in the software end of >it, and the hardware is somewhat foggy. What you are interested in is called an integrated solar flux measurement. NASA spent many thousands of tax dollars perfecting this measurement under the guise of solar energy research (had something to do with Shuttle detonations or something space-related like that :-). I remember several articles in the NASA Tech Briefs on this subject. You should hit the library and look thru the indexs. All the devices I remember output a voltage proportional to the instantaneous solar flux. You will therefore need to get a data acquition card (A/D) for your PC. Most of these come with some sort of driver software. What you would do is sample the device output at suitable intervals and average it over the interval of interest. I'd probably sample once a minute and store the hourly averages in a database. You could then calculate a longer average or do other nifty tricks. I can almost hear the next question. "How do I digitize plant growthrate?" :-) -- John De Armond, WD4OQC | Manual? ... What manual ?!? Sales Technologies, Inc. Atlanta, GA | This is Unix, My son, You ...!gatech!stiatl!john | just GOTTA Know!!!
markz@ssc.UUCP (Mark Zenier) (04/10/89)
In article <102@raider.MFEE.TN.US>, root@raider.MFEE.TN.US (Bob Reineri) writes: > I've recently planted our first garden, and being the computer nut that I am, > love to keep records. The rainfall and temperature are easy enough to get. The > other item I would like to track is the amount of sunlight the garden gets on > a daily basis. I am entering all this into a database so I'll have something > to ponder over the next winter. > > Does anyone have any ideas on what might be a suitable circuit for this applic- > ation ? One neat thing was published in Whole Earth Review/ COevolution Quarterly. A big Fresnel lens and a board. The focused sunlight burned the board showing the sunlight or lack of it. A new board every day. If that's not high tech enough, you could get a TV camera and a frame grabber to read off the days board. Mark Zenier uunet!nwnexus!pilchuck!ssc!markz markz@ssc.uucp uunet!amc! uw-beaver!tikal!
aj-mberg@dasys1.UUCP (Micha Berger) (04/12/89)
Bob Reineri writes: > I do have one idea: Perhaps a solar cell, connected thru an RC network, that > would charge up a capacitor to a given voltage, depending on the amount of > sunlight received over the course of a day. Then I could somehow measure the > charge on the cap at the end of the day. Just a thought.... Here's my 2 cents. Use an op-amp integrator to integrate instead of the capacitor. Have a photocell as the input voltage to be integrated. This way, at the end of the day all you gotto do is read the voltmeter at the integrator's output, and hit a reset button. The only thing I haven't I haven't figured out is calibration. -- Micha Berger Disclaimer: All opinions expressed here are my own. The spelling, noone's. email: ...!cmcl2!phri!dasys1!aj-mberg Aspaklaria Publications vox: (718) 380-7572 73-32 173 St, Hillcrest, NY 11366
mattp@oakhill.UUCP (Matt Pressly) (04/14/89)
In article <9318@dasys1.UUCP> aj-mberg@dasys1.UUCP (Micha Berger) writes: >Here's my 2 cents. Use an op-amp integrator to integrate instead >of the capacitor. Have a photocell as the input voltage to be integrated. It looks like even small leakage through the feedback capacitor in the integrator would cause pretty inaccurate readings, especially after integrating over a period of around 12 hours. -- address: mattp@oakhill
aj-mberg@dasys1.UUCP (Micha Berger) (04/18/89)
I wrote: > Here's my 2 cents. Use an op-amp integrator to integrate instead > of the capacitor. Have a photocell as the input voltage to be integrated. Matt Pressly wrote: > It looks like even small leakage through the feedback capacitor in the > integrator would cause pretty inaccurate readings, especially after > integrating over a period of around 12 hours. Sorry 'bout that. My "experience" with circuit design was at Columbia Univ. You ever notice that when you are a student capacitor's don't leek, noise isn't a function of circuit layout, etc... Which leads me to make next suggestion: All employers: Hire colledge students to design and assemble your product. The obvious advantage of putting out circuits that use ideal components will eat up the extra R&D costs. Seriously, why isn't their a course on "Removing the Simplifying Assumptions"? -- Micha Berger Disclaimer: All opinions expressed here are my own. The spelling, noone's. email: ...!cmcl2!hombre!dasys1!aj-mberg Aspaklaria Publications vox: (718) 380-7572 73-32 173 St, Hillcrest, NY 11366