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sorenb

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Posts posted by sorenb

  2. KGSSHV Carbon Build Thread

    in Do It Yourself

    Posted

    12 hours ago, Whitigir said:

    I thought I only need Low voltage to be able to adjust the current, offset, and balances trims ?

    You can trim the CSS's using only LV and a DMM in mA mode (assuming AMP board is not connected to anything):

    Connect LV+ -> AMP HV+
    Connect LV- -> DMM (Common)
    Connect DMM.(+) -> the probe
    put the probe to the tail of the CSS (the Drain of the Sics (middle leg))
    Now you'll have the CSS current reading directly on the meter, and the CSS can be trimmed to what ever current < 27mA you have sinks for
    (one might shoot a mA lower as the current grows a bit at higher voltage and heat).

    Trimming the output stage tail resistor to get the amp in balance and DC balance requires all voltages

     

     

    • Like 3

  11. Mini Group Buy - Blue Hawaii PCB

    in Do It Yourself

    Posted

    59 minutes ago, nopants said:

    the board cost will be minuscule compared to the rest right?

    I guess gwrskien has a point as some fab houses do charge extra going for more oz ... however, in rgrds to PCBNet it doesn't really make much difference.
    For re-work abuse 2oz is usually fine - 1oz typically cannot handle much abuse .
    @nopants in comparison to how much green we are speding on components, chassis and so forth, I agree ...doesn't really matter much

     

  14. Kevin Gilmore Circlotron Output, Large Enclosure [high-slew] Electrostatic Amplifier

    in Do It Yourself

    Posted

    as far as I remember I use 12V+5V back2back 1W's ...probably not critical 
    22awg is probably plenty

    For testing you can:
    Power up: bring up the drivers - wait until output settles - bring up the output stage
    Power down: bring down the output stage - wait until the HV900 < 200V - power off the drivers
    That works for me.

    Keeping the HV900 < 200V you can investigate the troubling behavior, having meters on the current limiter resistors of output stage and HV900s

    As far as I understand from Kevin he hasn't had problems in the lab, but he used some film on ceramic resistors at 10W's for current limiter.
    The DigiKey you found  is 100W/700V rated and will most likely not break down.

  15. Kevin Gilmore Circlotron Output, Large Enclosure [high-slew] Electrostatic Amplifier

    in Do It Yourself

    Posted · Edited by sorenb

    On 2/13/2017 at 2:24 AM, JoaMat said:

    Just switching to 100 watts resistors will that protect us from exploding output board and associated PSUs?

    I would assume that having some more robust 120ohm's will easen things quite a bit, as it will take a considerably amount of time before a pair of those break down, and at that time the current limiter from the HV900 should have kicked in and the situation being under control until the driver output has settled

     

     

  16. Kevin Gilmore Circlotron Output, Large Enclosure [high-slew] Electrostatic Amplifier

    in Do It Yourself

    Posted · Edited by sorenb

    15 minutes ago, kevin gilmore said:

    they are wirewound, not sure how much inductance that is going to add, or whether its going to cause any trouble.

    I would probably use these

    http://www.vishay.com/docs/50051/lto100.pdf

     two of those in series to get to 1kV for the 120ohms ...well only 100ohms are available ...so four it is

     

  17. Kevin Gilmore Circlotron Output, Large Enclosure [high-slew] Electrostatic Amplifier

    in Do It Yourself

    Posted

    On 2/9/2017 at 6:24 PM, Tinkerer said:

    How would you fix this? Bigger resistor? Two stage startup? But for me the outputs blew after around three to five seconds. It wasn't immediately at startup.

    A Resistor capable of withstanding more current briefly. A more bold and faster transistor in comparison to the tiny 1-watt BC-thing

    As I have stated on page 3, powering up the driver and let it settles before dialing in the output bridge will bring the Albatross up in the Air; landing is likewise a bit delicate, and turning off the HV900's before the drivers works.
    I suspect that the 120ohm's also needs to be of a more bold character to prevent this thing for going boom - maybe 100W bolded to the heatsink. 

  18. Kevin Gilmore Circlotron Output, Large Enclosure [high-slew] Electrostatic Amplifier

    in Do It Yourself

    Posted

    43 minutes ago, Tinkerer said:

    Somebody correct me if I'm wrong but I think you need the opto input from the Output V1.

    you can tap it off the drains of the SiC's at the driver board using some resistors.

    20V offset will whack the bridge out of balance and raise the current flowing.
    The zeners at the gates provides some protection in that regard, but I suspect that those are slower in comparison to the SiC's and that is the culprit.
    I suspect the HV900 current limiter isn't robust enough for being literally 'shorted' for a very brief moment when the driver at power up/down swing to B+

    • Like 1

  23. Ether Flow vs HD800s vs Stax vs vs vs

    in Headphones

    Posted · Edited by sorenb

    6 hours ago, mypasswordis said:

    If you read enough HC posts you would know that once you go Stax you never go bax, unless you are Fang Bian. No pesky boxed dynamic woofer to get in the way of the electrostatic goodness, either. O0  

    Pars isn't going to be happy about your spelling of Parsifal.

    U can go Bax with Stax: Tintagel sounds good and, even the sick Tristan is quoted herein 

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