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| michka:research:microbial_fuel_cells:brussels7 [2017-09-20 17:29] – michka | michka:research:microbial_fuel_cells:brussels7 [2017-09-20 17:43] – michka | ||
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| * The voltage drop between the + input pin voltage and the output voltage seems to be around -0.15 to -0.2 V. | * The voltage drop between the + input pin voltage and the output voltage seems to be around -0.15 to -0.2 V. | ||
| - | ===Discussion, conclusion, future work=== | + | ===Discussion |
| * The current typology of the one-transistor version of the circuit does not give the BBC microbit a long autonomy because there is a mismatch between the nominal charge voltage of the supercap, the minimal power supply voltage of the BBC microbit, and the voltage drop across the circuit. Possible options to overcome these pitfalls include : | * The current typology of the one-transistor version of the circuit does not give the BBC microbit a long autonomy because there is a mismatch between the nominal charge voltage of the supercap, the minimal power supply voltage of the BBC microbit, and the voltage drop across the circuit. Possible options to overcome these pitfalls include : | ||
| Line 173: | Line 173: | ||
| ==Test #10 - Changing the transistors== | ==Test #10 - Changing the transistors== | ||
| - | | + | |
| - | | + | * I replaced the 2N3904 with each of them and watched how the circuit performed. |
| + | * Regarding the SS850BBN transistor: | ||
| + | * The voltage at the + pin of the power supply was 2.81 V. | ||
| + | * The voltage at the 3V pin of the BBC microbit was 1.98 V. | ||
| + | * The voltage at the output pin of the 1381E was 2.69 V. | ||
| + | * The collector-emitter voltage drop was 0.71 V. | ||
| + | * When running the BBC microbit on the supercap, the BBC microbit stopped | ||
| + | * Regarding the BC63916 transistor: | ||
| + | * The voltage at the + pin of the power supply was 2.81 V. | ||
| + | * The voltage at the output pin of the 1381E was 2.71 V. | ||
| + | * The voltage at the 3V pin of the BBC microbit was 1.98 V. | ||
| + | * The collector-emitter voltage drop was 0.73 V. | ||
| + | * Regarding the KSD5041QTA transistor: | ||
| + | * The voltage at the + pin of the power supply was 2.81 V. | ||
| + | * The voltage at the output pin of the 1381E was 2.75 V. | ||
| + | * The voltage at the 3V pin of the BBC microbit was 2.09 V. | ||
| + | * The collector-emitter voltage drop was 0.66 V. | ||
| + | * When running the BBC microbit on the supercap, the BBC microbit stopped to work when the voltage across the supercap reached 2.41 V, after about 25 seconds operation. | ||
| + | | ||
| ==Test #11 - Switching the 1381E for 1381J== | ==Test #11 - Switching the 1381E for 1381J== | ||
| * The 1381J voltage detector does not trigger at 2.8 V, probably because the voltage is too low, we therefore get a 0 voltage on the 1381J output, and a 0 voltage on the BBC microbit 3V power supply pin. | * The 1381J voltage detector does not trigger at 2.8 V, probably because the voltage is too low, we therefore get a 0 voltage on the 1381J output, and a 0 voltage on the BBC microbit 3V power supply pin. | ||
| - | * Conclusion : using the 1381J does not improve the autonomy of the BBC microbit. | + | * **Conclusion : using the 1381J does not improve the autonomy of the BBC microbit.** |
| ==Test #12 - Changing the BBC microbit output mode from analog to digital== | ==Test #12 - Changing the BBC microbit output mode from analog to digital== | ||
| Line 187: | Line 205: | ||
| * When powered through our one-transistor circuit, we obtain 1,75 V on pin 1, the same as on (analog) pin 0, input power pin 3V being powered at 1,84 V. | * When powered through our one-transistor circuit, we obtain 1,75 V on pin 1, the same as on (analog) pin 0, input power pin 3V being powered at 1,84 V. | ||
| * We therefore cannot hope that the BBC microbit will open the gate of the second transistor controlling the line powering itself, as the gate voltage will always be a little bit lower than the emitter voltage in this version of a two-transistors circuit. | * We therefore cannot hope that the BBC microbit will open the gate of the second transistor controlling the line powering itself, as the gate voltage will always be a little bit lower than the emitter voltage in this version of a two-transistors circuit. | ||
| - | * Conclusion : using the digital output of the BBC microbit does not improve the autonomy of the BBC microbit. | + | * **Conclusion : using the digital output of the BBC microbit does not improve the autonomy of the BBC microbit.** |
| ====Michka, September 16th==== | ====Michka, September 16th==== | ||
| Line 193: | Line 211: | ||
| ==Test #13 - Changing the supercapacitors== | ==Test #13 - Changing the supercapacitors== | ||
| - | * For some with higher nominal charge voltage | + | * For some with higher nominal charge voltage |
| - | * For some with higher capacity | + | * For some with higher capacity |
| * Elak needed one week delivery to provide supercaps, so experiment cancelled for now... | * Elak needed one week delivery to provide supercaps, so experiment cancelled for now... | ||
| - | * But, in the shower, | + | * But, in the shower, |
| ==Test #14 - Piling up supercapacitors in series== | ==Test #14 - Piling up supercapacitors in series== | ||
michka