Paper Done! & more....

Just turned in the paper to Dawn.  We are officially done with the hard part!  Working on tweaking my lesson plan and Dave is working on the tech fest game.  Tech Fest will be a blast this year!

Poster is finally done! I HOPE

We have tweaked and tweaked till this is what is considered complete. 

Looking Good

Dressed up the assemblies so that they would look more professional today.  Had to mount the two boards required for the CO2 sensor/transmitter on a piece of wood.  Used #6 screws with 1/4" teflon standoffs.  Hopefully it looks good enough for being a prototype.  Fan wires are soldered to the board now.  Sharin & I tested it and everything is working as planned.  There is a little difference in voltage readings, but this will get addressed on Monday.

Sensor Board Updates

Spent yesterday afternoon soldering.  Sharin & I wanted to get the protoype off the bread board and into a permanent home.  The specific board we worked on was the receiver that communicates with the computer.  Looks much better with appropriate length wires. :-)

This morning was also very productive.  I started out at the hardware store looking for screws to mount the CO2 sensor/transmitter boards.  Miss judged sizes, so I had to make a second trip.  (This time I took a generic board for reference.)  Bought #6 screws & 1/4" teflon standoffs for mounting the boards to a 4" x 4" piece of wood.  The boards are mounted next to each other and we are now working on shortening the wiring to make it look better.  Functioning great!  Blow into or talk over the CO2 sensor & the fan kicks on right on que.

More to come.

The Plan

Actually, the plans. As the last trial with the cinder block takes place, I start to design the Tech Fest carnival apparatus. I trying to decide whether we should have 3 or 4 stations. We have the technical equipment for 4, but would it benefit us to have one more? I'l go ahead an design it, but go to EESAT and see the size of the room before buying materials. Off to plan...
(insert time here)
OK, done.
I just gotta buy the stuff and build it now.
Parsons

oh yeah, and we put a cinder block in an enclosure with 20000ppm CO2 and in 3 hours or so, it dropped below 200ppm. The room we were in was at 700ppm.

Monday, the first thousand light bulbs

Over the weekend, I took my large syringe to my room at school and calibrated it with water and a triple beam balance. I wanted to see whether or not the markings on the side of the syringe were in fact legitimate. If not, at least I will have measurements so that I know what each gradation actually is. According to http://www.csgnetwork.com/waterinformation.html tap water at the temperature I measured it at, has a density of .99624g/mL (interpolated).

 The slope (also the density) from my data was .9965g/mL accurate to 3 sig figs, so I have no worries about the precision of my instrument.

So today, one of the goals will be to oblige Dr. Rudi and place various building materials in a container with some CO2 and see if there are any changes in that level. Do the building materials exude or absorb the CO2. I expect nothing to happen, but that remains to be seen. I will try to test in the region where our fan will operate, 1000-5000ppm.

• First up: 2 pieces of dry wall about 5" x 26"(unpainted, unplastered)- no appreciable change

• Second: 1 cinder block (new)- CO2 ppm drops more than expected. Must do a more rigorous test. Sealed the entire container with the cinder block and CO2. The CO2 level dropped down from 1200ppm to a lowly 200ppm. The room we are in is at about 800ppm, so there is no excusing the drop in CO2. Upon doing some research, I see that to create lime in cement (and cinder blocks) CaCo3 is heated to 500-600 degrees celcius to create CaO and CO2. This reaction is reversible. Technically, the cinder block is a combination of coal ash, and portland cement, which is 3CaO•SiO2 and 2CaO•SiO2. Perhaps the CaO is being coaxed out of the block. This would eventually reach an equilibrium state, but it could take months for a new cinder block to reach that point. Very interesting, indeed!

• Third: 3 bricks (old)- no appreciable change

• Fourth: 2- 1sq. ft. ceiling tiles- no appreciable change

• Fifth: 1 linoleum adhesive floor tile- 

• Sixth:  3 carpet samples- no appreciable change

• Seventh: 2 small plants (a fern and a caladium)- There seems to be a trend of rising CO2....hmmm. Have I been lied to all my life? I have just been told that plants generate CO2 and O2 in different situations. Does everybody know this? I could swear that my biology teacher said plants make O2 with no mention of CO2 production. What is the net result? Sheesh. Too many variables in this little test.

Later, Dave

Tuesday, grinding away...

So the CO2 sensor that we ordered has some issues... at least the spec sheets do. Yes, that was plural...spec sheets. On one spec sheet the output voltage is 30-50mV, and the graph it provides reads that the output voltage is 265-325mV. On the spec sheet for the module the CO2 sensor plugs into, it refers to the CO2 sensor having a voltage output of 100-600mV. What?!?!?!?

It appears we must do our own calibration, using the grey wolf as gospel truth. Over 2 hours of careful measuring, we plotted the voltage function of the sensor in relation to the CO2 ppm and took 37 points of data, more closely spaced where we would be using the sensor. We measured from 800ppm to 80000ppm and found that the sensor becomes less responsive at very high concentrations. On a log graph, it looks fairly linear. The y-axis is ppm and the x-axis is voltage output by our sensor.

With that many data points, it should be fairly easy to interpolate ppm based on voltage. Our range of concern is between primarily 1000-5000ppm. The actual data looked like this, although the program cut off the first 25 minutes.