calculating voltages between nodes of a circuit

Discussion in 'General Electronics Chat' started by mikewax, Oct 15, 2016.

  1. mikewax

    Thread Starter Member

    Apr 11, 2016
    here is a picture of the voltages across the different components in my circuit. The purpose is to charge a pair of supercaps one at a time, first C1 then C2. At this point in the picture, C1 has just finished charging and i'm measuring the various voltages.
    the sequence goes as follows:

    initial state: V_{C1} = V_{C2} = 0
    transistors Q1, Q2, and Q4 remain in the cutoff state.
    1- A = LOW, B = HIGH (begin charging C1, current goes from p->r->v->z )
    2- when C1 reaches 2.5v, A goes HIGH and B goes LOW (all Qs now in cutoff).

    all voltage readings are made roughly at the moment of cutoff as C1 starts to discharge.
    can someone help me with the arithmetic? i can't figure out these voltage readings.
    thanx, louie
    Last edited: Oct 15, 2016
  2. ci139


    Jul 11, 2016
    at the time i figured out the wave form diagram for the symmetrical astable multivibrator only knowing the Ohm's Law and some basics of bjt - without computing anything just simulating the circuit in my mind - i was amazed to confirm with the multimeter and a diode the negative voltages developed at the bases (it was before the internet era, i didn't own a PC then until few years later (and i was one of few in my country to have 1 then) - at secondary school time)

    so basically draw out the circuit wave forms - divide/group it to a different cycles operation - just exacten/correct the voltage values using www for any formulas needed