Switching

Discussion in 'General Electronics Chat' started by falconite, Nov 12, 2010.

  1. falconite

    Thread Starter New Member

    Nov 6, 2010
    23
    0
    Hello everyone

    I have 10 capacitors of the same value C_S charged to different voltages (2V,4V...20V).
    I need to connect them to another capacitor C_L one at a time.

    To put it more clearly, say from t=o to t=t1, C_S_1 should be connected to C_L.
    From t=t1 to t=2*t1, C_S_2 should be connected to C_L, and so on.

    I have with me a supply voltage of 2 and a clock signal of 2 V peak to peak.

    If i use SCR s as switches(one for each of the 10 capacitors) and connect the other end of the SCRs to C_L, i can turn each one on and off in a sequence,using the clock signal.

    The problem is will the SCR work for such low voltages (around 2V to 20V)???
    [​IMG]
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    While the SCRs should work fine at those voltages, they are DC devices and will not shut off until current through them has dropped to a very low value. That is a sort of permanent on switch.

    What is the significance of the 2 volt supply and clock?
     
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,170
    395
    After dumping 2V-C into CL, if SCR does not turn off, it will as soon as 4V-C is dumped into CL. Need to also consider SCR leakage, mavbe as high as 1o μA.
    Whynot combine both posts.
     
  4. falconite

    Thread Starter New Member

    Nov 6, 2010
    23
    0
    @beenthere...

    Hello...
    I am aware of this holding current limitation.
    Since i am transferring charge between the capacitors (via the SCR) the holding will ultimately drop to almost 0 ,once the capacitors attain the same voltage.
    But this may take a long time right???

    And about the 2V, actually i started the problem with the 2V supply and the clock.
    I will use a boost converter to generate 20-22 V and charge up the capacitors.
     
  5. falconite

    Thread Starter New Member

    Nov 6, 2010
    23
    0
    @Bernard....
    Hello...

    Actually I thought that since this switching is sort of a different issue I should introduce this in a new post.

    The SCR will eventually turn off,but I would feel more comfortable if I could turn off the switch somehow externally,and not depend on wen the capacitors get charged.

    Can this be achieved through some switching mechanism.

    MOSFETs would be nice...:)
    But n-MOS wont transfer the total voltage,and p-MOS would remain on unless i apply some signal at its gate.
     
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