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Class AB amplifier

Discussion in 'Electronic Design' started by Simon Burley, Dec 6, 2007.

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  1. Tim Williams

    Tim Williams Guest

    Either:
    The 6BK4C (and similar types), a beam triode -- so constructed to prevent
    ions from destroying the rare earth oxide cathode, it was used as a shunt
    regulator to control the high voltage directly;
    Or, a pulse shunt regulator like the 6HS5, also a beam triode with very low
    perveance but very high current and voltage capacity and gain. These were
    used to control the height of the flyback pulse as it took place (at the
    sweep tube's anode, so big peaky voltages!), thereby regulating HV.

    Tim
     
  2. Phil Hobbs

    Phil Hobbs Guest

    Brr. Bet that died of cathode inactivity pretty fast--you'd have been
    exceeding the space charge limit 100% of the time, no?

    Cheers,

    Phil Hobbs

    Honorary President,
    American Society for Prevention of Cruelty to Cathodes
     
  3. Jamie

    Jamie Guest

    Are you looking for a bridged output using all NPN's HV transistors
    by any chance?

    I did something like that years ago for a beam deflection circuit
    on a Irradiation circuit. We didn't use HV transistors in that circuit
    how ever, It could be applied here.
    It was a bridged output using all NPN's (4). Inverted drivers to
    isolate the HV for the low voltage OP-AMPS we were using.
    In our circuit, we were only dealing with 80 Volts but the Op-amps
    could only handle 36 max.
    Feed back was voltage divided and the (+) input was offset a bit from
    the norm to compensate for that division factor.

    One op-amp to drive the source NPN side while the other referenced the
    source driver side in a voltage comparator mode to drive the sink NPN
    output.
    2 sets of these joined with a phase split circuit to drive the
    magnetic coils.

    That's a general run down, I would have to dig out the print and scan it
    if there is any interest.

    P.S.
    If did run a little warm :)
     
  4. John Larkin

    John Larkin Guest


    The worst was a neon sign transformer-1B3 rectifier-oil cap bank for a
    flashtube, charging to just under the spontaneous breakdown level, 7-8
    KV maybe. The abuse level - high filament voltages to get fast
    charging - must have been extreme. It never failed, after maybe a year
    of moderate use.

    I was a weird kid.

    John
     
  5. John Larkin

    John Larkin Guest


    I was thinking of the 8068. I think.

    John
     
  6. Tim Williams

    Tim Williams Guest

  7. Fred Bloggs

    Fred Bloggs Guest

    The schematic on P2 shows a higher speed circuit which supports 50us
    scans it looks like...
     
  8. JosephKK

    JosephKK Guest

    Simon Burley posted to sci.electronics.design:
    There are such things as slow-scan scan converters. It must be over
    three decades ago, that i last heard of trying to output slow scan
    directly to a CRT.
     
  9. JosephKK

    JosephKK Guest

    Tim Williams posted to sci.electronics.design:
    Not quite, that is 1 Watt.
     
  10. John Larkin

    John Larkin Guest

    Well, how close to the positive rail would you want it to swing?

    Do the math.

    John
     

  11. Maybe a differential amplifier output stage? Similar to the one a bit down
    the page here: http://web.jfet.org/vclk/
     
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