An excellent suggestion - yes I definitely don’t need high audio quality, just something to oscillate a platform so I’ll take a look. This one looks promising, it has I2C control also to help with automation: Stereo 2.8W Class D Audio Amplifier - I2C Control AGC - TPA2016 : ID 1712 : $9.95 : Adafruit Industries, Unique & fun DIY electronics and kits
Solar Cyan
Something else that can be done with the outer Cyan box…it can prop up a 10 W solar panel to charge two series-connected 6V sealed gel batteries through a charge controller to power the box’s fan. The fan connection is made through a 12V-5V USB cigarette socket adapter so I can just plug in the USB-powered fan already on the outer box…The inner Cyan box is used just as a spacer to hold the hummus container.
The batteries are currently pretty low and it’s overcast outside…once they’re charged enough, I’ll run a test. I plan to use a coffee filter with input material as usual, but below the coffee filter will be a wet sponge to constantly keep the material wet from beneath but not soaking. No huge amount of standing water anywhere, which is good since I have batteries nearby. Will see how well this setup does as there won’t be any humid air in the outer box, just moisture wicking from the bottom up.
There’s nothing to plug in and it’s super portable - I took my Cyan downstairs holding onto nothing but the solar panel in one hand and the file box handle in the other. Probably weighs about 10 pounds, mostly due to the batteries at the bottom.
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Solar Cyan, Part 2 - my record for CO2 capture so far
It took a few days to get these depleted batteries charged enough to go for a full day’s run time. On May 15 I did my first run entirely on solar/battery power.
A big change from previous setups: For the roughly 8 hours of wetting time, I kept the fan at low power the entire time. There was no longer an air pump; I put the hummus container on top of the small box as shown in the picture from the last post. I then put a brand new regular dish sponge in the container and filled it up with water until the sponge was completely wet and the bottom of the sponge was sitting in about 1/4" of water. I didn’t want it to dry during the run and this would turn out to be plenty of water.
The coffee filter with the input material (I used Ca(OH)2 here to compare to earlier tests) was then placed on top of the sponge. The sides of the coffee filter would likely be blown over by the fan so I folded the sides over the hummus container as much as I could.
I let it run for 8 hours with the fan on, then removed the hummus container from the box + fan. I let it dry overnight but in the morning the sponge was still wet, so I removed the filter paper from the sponge so it could dry on its own. This was at the 22 hour mark that drying actually started.
I didn’t check the weight until 5 days later to make very sure it was dry. From past experience it should have been dry late on day 2, but we had a few rainy days where the humidity was around 30-35% and I wanted to wait until humidity levels returned to where they were at the beginning of the run (~25%).
Total weight when dry = 12.59 g
Filter weight = 0.85 g
Final weight of material by itself: 12.59 - 0.85 = 11.74 g
Initial weight of material by itself = 10.00 g
this equals a weight increase of 17%, equivalent to a CO2 capture amount of 2.95 g.
Inconclusive results with new setup - watch your sponges!
Scratch the 2.95 g from earlier, we do not have a new record. The dish sponge I had used earlier left some sort of residue on the filter paper after it had fully dried. I had initially thought the residue was the result of humidity on the filter paper, but after I repeated the experiment with a Magic Eraser sponge I did not get any increase in CO2 capture from previous levels. I did two experiments with each sponge and each time the dish sponge had a much higher weight (from the residue) compared to the Magic Eraser.