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Measuring Trigger Current

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  • Measuring Trigger Current

    Hi All,

    I'm having trouble measuring my trigger current as described in this video. Any help would be great!

    Bedini SG - Tracking Trigger Current - YouTube



  • #2
    Hi Joster, I'm not sure why you would want to measure the trigger current. It's not something I've ever tried to measure or had any reason to measure. In any case, are you measuring AC current or DC? It should be AC. Also, I would not be connecting any part of the circuit to your laptop - the radiant spike can get in there and destroy it.

    I would be looking at why your machine is pulling 3A, it should be no more that about 1A on that setup. Your base resistance is probably too high, try adjusting your base resistor potentiometer for the fastest RPM and lowest current draw.

    With your cap pulser, what voltage are the capacitors dumping at? Looking at your setup and the 4 x 680uF caps (2,720uF) I would expect them to be dumping at about 25v approximately 10 times/second. I see you are using an Arduino to time the cap dump, but you will need to adjust the timing so you don't cook those caps.

    The reason why your meter is doing what it is, is because digital meters are not fast enough to catch the voltage spike. What you are seeing is the "average" voltage over a long period of time. The increase in voltage every 10 or so minutes is the meter freaking out because it can't effectively average out the voltage spike. Different meters behave differently. If you really want to see the voltage on the battery terminals, hook a scope with 10x probes to it.

    John K.


    • #3
      Hi John,

      I just figured it was a good idea because it would determine how fast my input battery is drained. All my analogue amp meters are DC so I tried a digital meter on AC and it says its drawing about 130mA and the wheel is spinning very good. That's with no base resistance. I figured since I'm reconverting the radiant with the cap dump i'd be ok with the laptop connected.

      Regarding base resistance, I have 1 470 Ohms resister on the base of all the devices that's soldered into the board. Do I need to adjust these? I have put a pot in series with the trigger winding to tune. I's that correct?

      Currently the caps are dumping at 37V or so. I have two of them paralleled right now (2x 6800uF). They are dumping once every 2 seconds. When I adjust it below 2 times a second the pulse becomes too weak to do anything. I must have something wrong there.

      So in order to accurate track the charging I would need an oscilloscope? I will be getting one soon so it will be cool to try that.


      • #4
        If I add the other two 6800uF caps in parallelthey will dump at a lower voltage which is around 25V or so but doesn't seem to do much in the way of beefing up the current pulse to the battery.


        • #5
          I have also tried putting a few different kinds of DC bulbs in series with the trigger but they do not light. I suppose if I was actually pulling 3A they would be more than lit.

          Also, how have you been making out with the Alum battery conversion you where working on and where did you get that awesome battery analyzer!


          • #6
            Joster, just a misunderstanding with the terminology. I think you are trying to measure the draw current fom the primary, not the "trigger" current? When you said trigger current I thought you meant the current in the trigger winding.

            An analogue DC amp meter will be fine for doing that. Is that where you are seeing 3A?

            I thought I heard you say 680uF caps on the video, not 6800uF. Your cap dump rate is probably about right then.

            The battery analyser is a West Mountain Radio CBAII. Great for charting charge and discharge curves.

            I have not had a chance to get back to the Alum batteries as the correct Alum is very hard to get in Australia.

            John K.