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Dropping 1V from a Regulated 6V Wall Wart

Discussion in 'Electronic Repair' started by Watson A.Name - Watt Sun, Dark Remover, Dec 29, 2003.

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  1. John Fields

    John Fields Guest

    I agree.

    Plus, you won't have the Zener tempco and delta VZ/delta IZ (small
    though it might be since the change in IZ will only be caused by the
    change in the transistor's Ib as the load current goes from 0mA to
    200mA) to contend with. And, a BIG plus for the LDO, you won't be
    dissipating the power the Zener will be _all the time_ , regardless of
    the load current.
  2. John Fields

    John Fields Guest

    Any common 5.6V 500mW Zener will have its Zener voltage specified at a
    particular test current; 20mA. This current is what _must_ flow through
    the Zener in order for the reverse voltage it drops to fall within the
    bounds specified. 40mA will not only waste 20mA, it could cause the
    Zener voltage to be out of spec. The beta of the transistor (more
    properly the alpha) is almost unimportant in this case since the base
    current will be very small compared to the collector/emitter current and
    its change will have very little impact on the Zener current from
    no-load to full-load.
  3. John Fields

    John Fields Guest

  4. Active8

    Active8 Guest

    Yes. It's been fun. I love this groups sense of humor.
    And I also like to play. See what I mean? I didn't spell out what I
    meant or add an emoticon, and *my* meaning wasn't clear.
  5. Active8

    Active8 Guest

    I glanced at a generic curve. Not even sure where the Zener specs
    (if any) *are* on this box.
    Yes, Beta's just for rule of thumb stuff. Base current is
    negligible which is the idea of the pass trans, anyway. It allows a
    practical resistor for such a small drop, whereas not using it
    forces the resistor to handle most of the current and you know...
  6. I read in that Active8 <[email protected]> wrote (in <>
    ) about 'Dropping 1V from a Regulated 6V Wall Wart', on Tue, 30 Dec
    Doesn't ALT0223 on the numeric keypad, with Num Lock on, work?
  7. Active8

    Active8 Guest

    yeah. Chaos uses ctrl+alt+m for mu, etc. and that didn't work but
    rang a bell.

    I checked unicode and character map and it says the unicode number
    is 03B0 or 944

    ? <== that's 03B0 or 944 obviously not ß (0223)
    ? <== that's 0994
    ¯ <== 223 a bar |
    ß <== 0223 beta | these two foul me up. the leading zero matters.

    ok 03b0 is for arial and 0223 is for courier. I didn't know unicode
    encoded the font, just language or locale. i see it doesn't for the
    standard ascii chars. odd, really.

    It's all hex. no decimal charts on MSDN CD. ok another instance of
    the sci calculator on the desktop where the reader sits won't hurt
    or just paste from char map.

    Thanks for the clue, John. Sorry if I'm still a bit clueless.
  8. I read in that Active8 <[email protected]> wrote (in <>
    ) about 'Dropping 1V from a Regulated 6V Wall Wart', on Tue, 30 Dec
    No, this is "Windows 'extended ASCII' characters", not Unicode and 0223
    works for any font that contains the character.

    There are two different series; one of the form 'ALT1nn'and 'ALT2nn',
    which are in no logical order and the other in the series ALT0128 (which
    is €, the Euro symbol) to ALT0255 (which is ÿ). Not all of the
    characters will show on the screen.
  9. John Fields

    John Fields Guest

  10. John Fields

    John Fields Guest

    You ß believe it!

    On mine, with NUMLOCK off, ALT 225 = ß, and ALT 223 = ¯

    while ALT 0225 = á and ALT 0223 = ß

    with NUMLOCK on, ALT 225 = ß and ALT 223 = ¯

    while ALT 0225 = á and ALT 0223 = ß
  11. Jim Thompson

    Jim Thompson Guest

    Wow! That's a BIG difference ;-)

    ...Jim Thompson
  12. Active8

    Active8 Guest

    Of course not. See my email addy? It says invalid ;) I don't try to
    foul things up, that'd be masochistic.
  13. Bob Parker

    Bob Parker Guest

    Isn't that too practical and simple?

  14. Active8

    Active8 Guest

    OK it does work in note tab lite regardless of font. What I meant
    was that if I'm looking up the code in character map, it changes
    for different fonts. It *does* say Unicode, also.

    So I don't have an extended ascii chart. ok. Nothing on MSDN CD. As
    usual, google rules when you know what to look for.

    says 225 is beta

    so does this:

    are we having fun yet?

    ok 225 is beta in the alt2nn series and 223 is a bar. alt0223 is a

    That second link came from

    which has a lot of possibly useful links.

    Thanks John,
  15. Active8

    Active8 Guest

    On 30 Dec 2003 08:57:05 -0800, said...
    Uh, yeah. I'm kicking myself in the ass. I'm the type who looks for
    simple elegant solutions like moveing the table closer to the
    handicapped person rather than try to move the heavy person to the
    table and I didn't think of the obvious.


    Nice to meet you , Wade! :)
  16. Ross Mac

    Ross Mac Guest

    Too easy Wade!....But still an interesting thread!
  17. I read in that Active8 <[email protected]> wrote (in <>
    ) about 'Dropping 1V from a Regulated 6V Wall Wart', on Tue, 30 Dec
    No. Both of your links give a DIFFERENT 'extended ASCII' series, not the
    Windows one. There is no standard for 'extended ASCII', so there are
    several different versions around.

    I found the Windows list in an early WordPerfect manual. But you can
    compile your own by just typing in the codes and noting the result.
  18. I read in that John Fields <[email protected]
    You need Num Lock on with some versions of Windows but with others it
    can be on or off. ON always works, AFAIK.
  19. Well, I started out in this or another thread with a RF modulator that
    requires 4.75 to 5.25VDC, probably because it would be off freq if the
    supply V got out of tolerance. I talked about the weird connector,
    someone said it's a Belling Lee connector, AKA Euro or PAL connector.
    Now I now what it is, and I bot an adapter at Rat Shack for four
    bucks. But I wanted something simple that I could solder onto the
    pins of the RF modulator, I finally resolved the problem by using a 6V
    unregulated wall wart, which is more like 7 or 8V, and a 5.1V zener,
    and 39 ohm resistor as a shunt regulator. It works just fine. But I
    still wanted a way to drop a single volt, with reasonable regulation,
    better than a 1N4003 diode which varies by up to a quarter volt. With
    a 1N4003 the voltage could be as high as 5.3 or 5.4V.

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