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| michka:research:microbial_fuel_cells:cardiff6 [2017-09-17 14:10] – michka | michka:research:microbial_fuel_cells:cardiff6 [2017-09-17 14:34] – michka | ||
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| * 2 spoons of FeO oxide thoroughly mixed in the mud | * 2 spoons of FeO oxide thoroughly mixed in the mud | ||
| * graphite rods cut to fit in the tupperware, and woven together with inox wire, with a vertical section insulated with the grey (+) plastic cover of a reclaimed multi-fiber wire. | * graphite rods cut to fit in the tupperware, and woven together with inox wire, with a vertical section insulated with the grey (+) plastic cover of a reclaimed multi-fiber wire. | ||
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| * A small bit of red mono-fiber wire is woven around the (+) electrode wire to clearly distinguish it from the (-) electrode wire | * A small bit of red mono-fiber wire is woven around the (+) electrode wire to clearly distinguish it from the (-) electrode wire | ||
| * both electrode wires are interwoven on the top to avoid the top (+) electrode to sink away from oxygen | * both electrode wires are interwoven on the top to avoid the top (+) electrode to sink away from oxygen | ||
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| * serpent-shaped (about 10 crossings across the tupperware) inox wire, with a vertical section insulated with the black (-) plastic cover of a reclaimed multi-fiber wire | * serpent-shaped (about 10 crossings across the tupperware) inox wire, with a vertical section insulated with the black (-) plastic cover of a reclaimed multi-fiber wire | ||
| * 1-cm-thick layer of graphite powder, mixed with tiny bits (about 1 mm long) of wool and water | * 1-cm-thick layer of graphite powder, mixed with tiny bits (about 1 mm long) of wool and water | ||
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| * (soaked) wool membrane | * (soaked) wool membrane | ||
| * mud | * mud | ||
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| ====2. Power Harnessing System==== | ====2. Power Harnessing System==== | ||
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| ===2.1 Joule Thief=== | ===2.1 Joule Thief=== | ||
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| * Paul is now trying a new design, where he tries to use the short burst allowed by the 1381E (few fractions of a volt of supercap voltage difference between opening and shutting down) to power the BBC microbit enough so that it can open the gate of another transistor (also 2N3904) to power itself directly from the 2.7V 1F supercap. Instead of the BBC microbit shutting down when the 1381 shuts down (around 0.2 V below its light-up voltage), it will shut down when the voltage provided by the supercap is too low to power the BBC microbit. The BBC microbit will then shutdown, closing the gate of the 2N3904 it controls, and thereby allowing the supercap to charge again. | * Paul is now trying a new design, where he tries to use the short burst allowed by the 1381E (few fractions of a volt of supercap voltage difference between opening and shutting down) to power the BBC microbit enough so that it can open the gate of another transistor (also 2N3904) to power itself directly from the 2.7V 1F supercap. Instead of the BBC microbit shutting down when the 1381 shuts down (around 0.2 V below its light-up voltage), it will shut down when the voltage provided by the supercap is too low to power the BBC microbit. The BBC microbit will then shutdown, closing the gate of the 2N3904 it controls, and thereby allowing the supercap to charge again. | ||
| * IT WORKED !!! (on a fully charged supercapacitory rating at 2.7 V 1 F) | * IT WORKED !!! (on a fully charged supercapacitory rating at 2.7 V 1 F) | ||
| - | * (Circuit scheme is drawn in “nice designs notebook”, | ||
| * When connecting a small motor to the BBC microbit on this same circuit, we have about 10 seconds of full motor operation on the 1F 2.7V supercap. | * When connecting a small motor to the BBC microbit on this same circuit, we have about 10 seconds of full motor operation on the 1F 2.7V supercap. | ||
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| * When connecting the input to the charge pump S882-Z, itself connected to a 0.3 V power supply (equivalent to 1 MFC), Paul observed that it would charge of 0.01 V every minute, which means that it would take 90 minutes to charge the supercap from his 1.8 V minimum (when the BBC microbit shuts down) to its 2.7 V maximum charging voltage. However, with multiple MFC in series, it might take less time. | * When connecting the input to the charge pump S882-Z, itself connected to a 0.3 V power supply (equivalent to 1 MFC), Paul observed that it would charge of 0.01 V every minute, which means that it would take 90 minutes to charge the supercap from his 1.8 V minimum (when the BBC microbit shuts down) to its 2.7 V maximum charging voltage. However, with multiple MFC in series, it might take less time. | ||
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| ===2.5 Charging a supercap from Mudwatts=== | ===2.5 Charging a supercap from Mudwatts=== | ||
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| ==2.5.1 Overnight parallel post-chip supercap charge== | ==2.5.1 Overnight parallel post-chip supercap charge== | ||
| - | =2.5.1.1 | + | **Results** |
| * We connected our three (inequally) working Mudwatts in parallel to a 0.22 F 2.5 V supercap. | * We connected our three (inequally) working Mudwatts in parallel to a 0.22 F 2.5 V supercap. | ||
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| * We would have expected a charge reaching 2.5 V, which is the maximum rating of the supercap… | * We would have expected a charge reaching 2.5 V, which is the maximum rating of the supercap… | ||
| - | =2.5.1.2 | + | **Consequences on the PHS design** |
| * … it is actually a limitation of the S882-Z chip, which will only charge up to 1.8 V (according to the datasheet). | * … it is actually a limitation of the S882-Z chip, which will only charge up to 1.8 V (according to the datasheet). | ||
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| ==2.5.2 1-hour parallel post-chip supercap charge== | ==2.5.2 1-hour parallel post-chip supercap charge== | ||
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| * We connected our three (inequally) working Mudwatts in parallel to a 0.22 F 2.5 V supercap. | * We connected our three (inequally) working Mudwatts in parallel to a 0.22 F 2.5 V supercap. | ||
michka