current through transducer

  • current through transducer

    Posted by harry on 27/11/2021 at 7:01 pm

    Can somebody tell me what will be the , when I switch the MOSFET pulser on? Unipolar, rectangular – 300V pulse. Few pulses per few seconds is ok – speed is not crucial, it can be slow.

    Can the ohms law be aplied to this -> 300 V / 50 ohms => 6 Amps?

    I ask, because I don´t have high voltage source and I will have to buy some (expensive) or build some. For this I need to know needed current values.

    If I can´t get any source with proper output current. I can make capacitor “energy bank” on the pulser HV pin, which will be powered by my low current power source.

    Other possibilty is to implement capacitor discharging pulser, like this:
    http://s9.postimg.org/5eipsuuxr/navrh.png

    As I understand, only problem with powering will then be capacitor charging time ( lower current – longer charging ).

    Hope I´m not missing something.

    Do you see any other possibilities?

    Anthony Wohali replied 7 months ago 2 Members · 1 Reply
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  • Power Sector

    Anthony Wohali

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    28/11/2021 at 3:34 pm
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    The width of the the negative HV pulse is determined by the time constant of the series capacitor and the load resistance, provided that the width of the ON drive to the MOSFET is long enough. Otherwise, not all the energy in the capacitor is delivered to the load.

    The time constant of the capacitor and the resistor from MOSFET drain to the ~300Vdc determines the recharge time and therefore the maximum PRF.

    For an cheap HV supply without winding a special transformer, I’d TRY a small transformer (say) 240V mains to 12-0-12V (24V centretapped) then use a couple of power transistors to turn it into an oscillator. From a bridge rectifier and smoothing on the 240V winding, which is now NOT connected to mains but acts as an output, I’d expect to get the 300Vdc (the actual voltage would depend on the DC input voltage to the drive transistors).

    TAKE CARE, EVEN THOUGH IT COMES FROM A LOW DC VOLTAGE SOURCE, YOU COULD STILL GET A NASTY SHOCK.

    You may also find HV sources on the internet (for flash tubes???)

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