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Michka Mélo, September 13th-14th, 2017

  • 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.

Test #1 - 1381E only

Test #2 - 1381E powering BBC microbit directly

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

1381E threshold characterization

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  • Last modified: 2017-09-14 14:58
  • by michka