[Prev][Next][Index][Thread]
Re: Iron core chokes (instead of ferrite & iron powder)
From: Antonio Carlos M. de Queiroz[SMTP:acmq-at-compuland-dot-com.br]
Sent: Friday, November 28, 1997 10:43 PM
To: Tesla List
Subject: Re: Iron core chokes (instead of ferrite & iron powder)
Adam wrote:
>
> The question is, are these eddy current losses relevant in our particular
> application (RF chokes)? We are not trying to make highly efficient RF
> transformers here, so shouldn't laminated iron cores be acceptable? They
> would need to be very well insulated, of course, but this is fairly easy
> to do with just polyethylene. Will the eddy currents be severe enough at
> 100-200kHz or so that the core would be heated or otherwise compromised?
> In short, what's wrong with insulated iron laminate cores for the tesla
> choke application?
Note that the RF chokes are effectively (one in series with the other) in
parallel with the primary LC resonant circuit (if there is a capacitor in
parallel with the output of the line-frequency transformer).
If they dissipate energy they act as resistors there, reducing the quality
factor of the primary resonant circuit.
The question is if the energy losses introduced are significant compared to
the losses in the spark gap.
Another problem is that conductive paths in the core of a choke act as
short-circuited secondary windings in a transformer, reducing significantly
the inductance of the choke at high frequency, and so its effectiveness as
protection.
--
Antonio Carlos M. de Queiroz
http://www.coe.ufrj.br/~acmq