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First build, have questions about scope traces

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  • First build, have questions about scope traces

    Hi
    I've built the beginner's energizer, done my darndest to follow the instructions, but it's not worked so far. So I decided to go back to a simpler circuit and try figure out what it's doing.
    I took some traces w/ a dual trace scope from the circuit below. Here's the first:
    Click image for larger version

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    This is a 10ms/div trace, the blue trace is attached to the base of the FET (the trigger wire), and the yellow is attached to the collector (a driver wire). You can see that both traces are at 4V/div.
    The first thing that bothers me is the shape (ignoring the spikey sections) of the blue trace. I was certain I'd see a trace like that described on P 51 or 55 of the SG Bedini advanced handbook.
    The second thing that has me wondering is all those spikes while the trigger has the FET turned on. I was totally expecting to see a nice low-going edge, and then a little while later a nice high-going edge - not this frantic oscillation.
    Someone else asked about a buzzing sound, and I wonder if this might be it?
    Now that I think about it, the spikes seem actually reasonable - when the FET goes on, the driver wire is energized, and that induces a corresponding current in the trigger, except that since the trigger wire is backwards to the driver, the yellow trace is inverted. Here's a more detailed shot of a spikey section:'
    Click image for larger version

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    a 500 microsec/div trace, but the V/div are the same as the first.

    This is a shot of the exact circuit I'm using for these traces:
    Click image for larger version

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    So that's my 2 questions - what's the deal w/ the overall shape of the blue trace (basically a sinusoidal shape)?
    Is that oscillation during FET on correct or ...?

    thanx
    r
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