High voltage converter not working properly

Discussion in 'General Electronics Chat' started by OrionV, Sep 1, 2016.

  1. OrionV

    Thread Starter New Member

    Jul 3, 2016
    22
    2
    Hello. I am trying to build a 9v to as much as possible converter. 9v battery > 2n3055 inverter like this one http://circuitdiagram.net/wp-content/uploads/2009/03/basic-inverter-circuit-design.gif > 4 stage voltage multiplier and a 470 pF, 2 kV capacitor in parallel after the multiplier.

    The capacitors on the multiplier are 3.9 nF, 100 V. The output of the transformer is around 80V and starts to drop slowly, I suppose that is normal. The problem is that the output of the voltage multiplier is only 20 volts! It charges up to a certain point, and after that initial discharge, which I can't measure because it's only for a fraction of a second, the voltage drops to 20V. I know that I am doing something very wrong, but I can't figure it out. Any help will be much appreciated.
    Thanks.
     
  2. tcmtech

    Well-Known Member

    Nov 4, 2013
    2,037
    1,663
    What is the current draw on the 9 volt battery when the circuit is running and what voltage does it drop down to at that load?

    9 volt batteries are terrible in applications that draw more than a few tens of milliamps.
     
  3. OrionV

    Thread Starter New Member

    Jul 3, 2016
    22
    2
    Can't measure, the multimeter starts freaking out and displays random numbers.....
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,127
    3,048
    Just measure the 9V battery's voltage during operation. It's probably sagging quite a bit. Or hook your circuit up to your car's battery.
     
  5. RichardO

    Well-Known Member

    May 4, 2013
    1,235
    384
    I am guessing that your transformer does not have enough inductance at the frequency that you are pulsing it. The resulting high current draw will kill a 9-volt battery quickly. If you connect the circuit to a power supply or battery that can supply the high current something might fry.
     
  6. OrionV

    Thread Starter New Member

    Jul 3, 2016
    22
    2
    Okay my bad, 130mA is the draw and the voltage drops to 1.7 volts, I wouldn't have thought of that. I thought the problem was the voltage multiplier. Would a wall charger provide constant voltage?
     
  7. wayneh

    Expert

    Sep 9, 2010
    12,127
    3,048
    You're heading towards a meltdown. Your experiment has revealed a flaw without destroying anything. You got lucky. Nature will not always be so kind.

    My comment about the car battery was tongue-in-cheek. I should have been more explicit: Hooking it up to a solid power source will likely make it go poof life a fuse.

    Be prepared to limit the current to a safe level before you supply more power.
     
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