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=====MFCitizen @Brussels===== **[[http://michkamelo.wordpress.com|Michka Mélo]], September 13th-14th, 2017** ====Abstract==== ====Tests with resistor-based voltage divider==== * FoAM's power supply does not go below 2.8 V of voltage. * In order to control the voltage to a lower threshold, I built a resistor-based voltage divider. * First version of the resistor-based voltage divider was made of a 100 ohms and a 10 ohms resistors in series. It worked but, smelled funny. After few runs, the 100 ohms had turned a nasty shade of black. It seems that the amount of current flowing in the resistor was too important because the resistor value was too low. * The second version of the resistor-based voltage divider was made of a 2.2 kohms and 1 kohms resistors in series. No weird smells, it worked. * However, I kept having funny results. I tested many of the components, and finally concluded with a test without the voltage divider that it might be perturbing the correct working of the circuit. * I will therefore not present here the hectic results of these first tests. ====Tests directly powered by the power supply==== ===Test #1 - 1381E only=== * When powering the 1381E voltage detector directly with the power supply (power supply + pin on 1381E pin 2, power supply - pin on 1381E pin 3, we obtain a 2.8V voltage on its output pin (pin 1), which is the same value as the one measured between the + and - pins of the power supply. ===Test #2 - 1381E powering BBC microbit directly=== * When connecting the BBC microbit 3V pin to the output pin of the 1381E (the GND pin of the BBC microbit being connected to the - pin of the power supply), the BBC microbit does not light up. The measured voltage on the output pin of the 1381E is 0.64 V. * It seems that the 1381E does not supply enough current to its output pin to power the BBC microbit. ===Test #3 - 1381E controlling 2N3904, which powers BBC microbit=== ===Test #4 - Power supply feeding 1F supercap, powering the circuit=== ===Test #5 - Power supply feeding 3F supercap, powering the circuit=== ===Test #6 - Power supply feeding 10F supercap, powering the circuit=== Explain why the second 2N3904 does not seem to light up. Tell the values of voltage drops ===Test #7 - Higher power supply voltage=== ===1381E threshold characterization=== ====Future work==== * Try out with higher

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