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Flying Capacitor +5DC to -12VDC/-12VDC

Discussion in 'Electronic Design' started by Guy Macon, Feb 22, 2004.

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  1. Guy Macon

    Guy Macon Guest

    Take a look at the following +5DC to -12VDC/-12VDC
    voltage multiplier/inverter:


    ------------o---------O +12VDC OUT
    | |
    +5VDC IN | | C
    O --- -----
    | / \ CR
    | --- -----
    |\| | |
    | \ | | C | |
    ---| O-------| |-------o ---
    | / | | | \ / GND
    |/|74HC04 | V
    | ---
    | / \ CR
    --- ---
    \ / GND |
    V |
    o------------ (+8VDC)
    | |
    | | C
    --- -----
    / \ CR
    --- -----
    |\ | |
    | \ U | | C | |
    ---| O-------| |-------o ---
    | / | | | \ / GND
    |/ 74HC04 | V
    ---
    / \ CR
    ---
    |
    |
    o------------ (+4VDC)
    | |
    | | C
    --- -----
    / \ CR
    --- -----
    |\ | |
    | \ U | | C | |
    ---| O-------| |-------o ---
    | / | | | \ / GND
    |/ 74HC04 | V
    ---
    / \ CR
    ---
    |
    |
    o------------ (0VDC)
    | |
    | |
    --- ---
    / \ CR \ / GND
    --- V
    |\ |
    | \ U | | C |
    ---| O-------| |-------o
    | / | | |
    |/ 74HC04 |
    ---
    / \ CR
    ---
    |
    |
    o-----------| (-4VDC)
    | |
    | | C
    --- -----
    / \ CR
    --- -----
    |\ | |
    | \ U | | C | |
    ---| O-------| |-------o ---
    | / | | | \ / GND
    |/ 74HC04 | V
    ---
    / \ CR
    ---
    |
    |
    o-----------| (-8VDC)
    | |
    | | C
    --- -----
    / \ CR
    --- -----
    |\ | |
    | \ U | | C | |
    ---| O-------| |-------o ---
    | / | | | \ / GND
    |/ 74HC04 | V
    ---
    / \ CR
    ---
    |
    |
    ------------o---------O -12VDC OUT
    |
    | C
    -----

    -----
    |
    |
    ---
    \ / GND
    V


    (Yes, I know about the noise and poor regulation...)

    I haven't worked with these before, and a few questions
    come to mind:



    DRIVING FREQUENCY:
    Is this just a simple matter of making it as fast as
    possible while still keeping the gate and diode switching
    times at a fraction of a percent? Or are there other
    considerations I should be thinking of?



    CAPACITOR SIZING

    Should the top and bottom C be much larger than the rest?
    (They *will* be if I use it to drive a board with bulk
    bypass caps on it...) Should the caps on the right be
    bigger than the flying caps on the left? How should I
    decide how big the flying caps should be?




    DRIVING PATTERN:

    Assume that the HC inverter is driven by six uP pins, and
    that the uP can put out any pattern at any reasonable
    frequency. What's the best pattern to drive it with?
    Should I switch one gate at a time, rippling upward
    through the six gates (in other words, have each driver
    be phased 60 degrees (360/6) later than the one
    below it)? Or is there a better driving pattern?
     
  2. I do not know the answer these questions, but it has also an
    incredible component count don't you think?

    I used this many times, even in industrial:

    -------------------------------- + 5V
    | |
    --- 10u |
    === /
    | b |<e
    | ---| BC557
    | | |\ c (general purpose PNP)
    | | \ 1N4148
    | | --------------|>|---------------- + 12V
    | | | | 1N4148 |
    |-- --- | {20t |-----|<|------ - 12V |
    | | 1t} | { | | |
    2k2 [ ] | | | { === --- ===
    | ----- | | | 22n === 10u --- 10u
    | pot core| | pol | |
    ---------------------------------------------------------- GND

    9 components, can deliver quite a bit of current.
    Mind the phase of the feedback turn.
    Decouple supply, but this does a sine wave like, so not much interference.
    Oscillation a few kHz.
    View with fixed font.
    C1 is not wrong way around, it charges positive relative to the + 5V.
    JP
     
  3. On a sunny day (Sun, 22 Feb 2004 12:01:58 -0800) it happened Guy Macon
    <http://www.guymacon.com> wrote in <>:

    Oops, drawing error, ,the cllector needs to be on tap of coil
    (or separate secondairy if you want isolation).
    Number off the extra turns sets voltage for both + and -

    -------------------------------- + 5V
    | |
    --- 10u |
    === /
    | b |<e
    | ---| BC557
    | | |\ c (general purpose PNP)
    | | \ 1N4148
    | | | -----------|>|---------------- + 12V
    | | | | | 1N4148 |
    |-- --- || {30t |-----|<|------ - 12V |
    | | 1t} | -{ | | |
    2k2 [ ] | | | {20t === --- ===
    | ----- | | | 22n === 10u --- 10u
    | pot core| | pol | |
    ---------------------------------------------------------- GND

    9 components, can deliver quite a bit of current.
    Mind the phase of the feedback turn.
    Decouple supply, but this does a sine wave like, so not much interference.
    Oscillation a few kHz.
    View with fixed font.
    C1 is not wrong way around, it charges positive relative to the + 5V.
    JP
     
  4. Guy Macon

    Guy Macon Guest

    Nice design! Mine uses 25 components, but the total cost is
    lower and mine has positive and negative outputs. Of course
    yours becomes a dual output with a transformer change and a
    few extra components. I am going to file it away for future
    reference. Thanks!
     
  5. hey, mine gives + and - 12 V, what do you mean?
    Anyways I am glad it is of use to someone.
    JP
     
  6. Guy Macon

    Guy Macon Guest

    Ooops. Looks lke my brain got a couple of the lower
    order address lines switched... Sorry about that.
     
  7. GPG

    GPG Guest

    Try this:



    A B
    +5V ->|---------o--->|---o---->|----o------- +V
    | | |
    In1 --- --- ---
    .- --- --- ---
    | |\ INV1 | | |
    |------| >O----------o | GND
    | |/ |
    | |
    | |
    | |\ INV2 |
    | .---| >O--o----------------o
    | | |/
    | |
    | | o----------------------------o
    | | | |
    | | | ---
    | | | ---
    | | |\ | || C |
    | |---| >O'-||---o--|<-----o------|<---o-----|<----o -V
    | | |/ || | | D |
    | | V | ---
    | | - | ---
    | | --- |
    | In2 === --- |
    | GND | ===
    | | GND
    | |\ |
    o------| >O-----------------o
    |/
    created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de
    Drive in 1 & 2 in antiphase
     
  8. GPG

    GPG Guest

    POST AGAIN



    A B
    +5V ->|---------o--->|---o---->|----o------- +V
    | | |
    In1 --- --- ---
    .- --- --- ---
    | |\ INV1 | | |
    |------| >O----------o | GND
    | |/ |
    | |
    | |
    | |\ INV2 |
    | .---| >O--o----------------o
    | | |/
    | |
    | | o----------------------------o
    | | | |
    | | | ---
    | | | ---
    | | |\ | || C |
    | |---| >O'-||---o--|<-----o------|<---o-----|<----o -V
    | | |/ || | | D |
    | | V | ---
    | | - | ---
    | | --- |
    | In2 === --- |
    | GND | ===
    | | GND
    | |\ |
    o------| >O-----------------o
    |/
    created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de
     
  9. GPG

    GPG Guest

    Fix?
     
  10. GPG

    GPG Guest

    Another go simplified


    |\ |\
    -| >O|-------------| >O-
    |/ A |/ B




    +5V ->|-----o------>|-----o----->|-------o----- +V
    | | |
    --- --- ---
    --- --- ---
    | | |
    A B GND

    A B A GND
    | | | |
    --- --- --- ---
    --- --- --- ---
    | | | |
    |-----|<------o------|<------o-----|<----o----- -V
    |
    |
    |
    V
    -
    |
    GND
    created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de
    Inverters could be paralleled sections to improve current drive
     
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