Re:: Simulation

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Charles Hobson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <charles.a.hobson-at-btinternet-dot-com>


----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, June 27, 2001 6:38 PM
Subject: Simulation


> Original poster: "Luc by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<ludev-at-videotron.ca>
>
> Hi guy
>
> I start to play with an electronic simulation software, I make a
> crude simulation of a primary circuit I put a couple of
> resistance on the circuit to be more realistic. One thing is
> strange normally the notch are explained by the exchange of
> energy from the primary to secondary and back. On my circuit I
> have notch but no secondary only a primary inductance could
> someone explain why I have notches, is it an artifact an harmonic
> or something else ?
>
> I put a gif of the screen capture at:
>
> http://pages.infinit-dot-net/luc2/simulation.gif
>
> Tx for your time,
>
> Luc Benard
>

A real puzzlement Luc. I played with similar set-ups but at much lower
voltages (12V rather than 3kV dc) and got the expected damped rf signal.
When I put a tuned circuit near the coul then nulls would appear like those
shown in your very nice gif.

Anyway I did the usual calculations on your circuit and got the resonant
freq. of 251kHz which appears to match yours on the scope if the time base
was magnified by 5. Noticing about 10 RF cycles between nulls that would
very roughly match a double tuned transformer with a coefficient of coupling
of around 0.3 or 0.4.   The  thing I noticed about your circuit was the 200
ohm pot. in series during the ringing. XL of the 20uH coil works out to
about 31 ohms, so to get ringing anyway near what you got this pot would
have to be set very low, maybe about 3 ohms or less. I suspect it is a wire
wound pot  adding some unusual reactance to the circuit. However, it's still
a mystery to me. I certainly wouldn't let loose of this situation until the
mystery was solved

Good luck

Chuck

Chuck