Re: [TCML] Oscilloscope methods for showing Ringdown

[DC Cox <resonance@xxxxxxxxxxxx>]

Here's how I do it:

Throw a HV diode in series with your xmfr output then put a large HV
resistor (10-20 meg) in series with your xmfr rectified output.  this will
fire once every 4-8 sec and give a clean single pulse from which you can
track the ringdown.  remember, when operating your HV cap on DC you
definitely have to discharge it before touching the circuit.

Dr, Resonance




On Wed, Mar 11, 2009 at 1:08 PM, Phil Tuck <follies@xxxxxxxxxxxx> wrote:

> Hello.
>
>
>
> I have spent most of today trying to get a descent scope image of my coil's
> ringdown. The primary charging curve did not present too much of a problem
> using a 20 x 10 meg resistors in series, but the secondary has not worked
> out well at all, despite what method I use.
>
>
>
> I seem to get a very poor 'scope image full of interference and refusing to
> sync' properly. I have tried manually syncing and even using a signal gen'
> as an external trigger by trying all different frequencies. The only way to
> view it has been to photograph it with a shutter speed that is quick enough
> to hopefully grab one of the multiple images you get on the scope's screen.
> I have shot 223 pictures today using various methods & over 200 are no
> good!.  I am only running the coil at 110volts (normally 240v 1kva) as it
> is
> in my shed and space is very limited, but I still have multiple streamers,
> or with a single breakout a strong 20 inch or so streamer to a grounded
> wire. I did indeed find  the best 'scope traces were obtained  with
> breakout
> to the grounded wire.
>
>
>
> The four best examples can be seen here
> http://www.flickr.com/photos/33962508@N03/?saved=1  There is some vertical
> banding on these which I take to be the notches, but they are not clear
> enough to say either way.
>
>
>
> I have tried hanging  probes near the coil ( I have used a x1, x10 and a
> x100) . I have also done the same but with different lengths of wire on the
> tips acting as an aerial. I then tried a coil around the secondary earth RF
> earth by winding 30 or so turns  around the earth lead and connecting the
> probe across that. Also tried just connecting the probe tip and leaving the
> coil open ended.
>
> I then made a coil up of around 40 turns on a 2 inch former and used that
> as
> an aerial instead, all without a great deal of success.
>
>
>
> I know about Terry Fritz's antenna that he designed though I do want to
> build one at this stage.
>
>
>
> My single channel old analogue 'scope (Hameg HM103) has seen better days
> and
> only has a small 7cm screen. I hate to blame this but I am wondering. Is it
> really necessary to have a storage scope to get good ringdown traces ?
>
>
>
> Regards
>
>
>
> Phil
>
>
>
>
>
>
>
>
>
>
>
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