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Re: Fw: Input frequency (fwd)
---------- Forwarded message ----------
Date: Tue, 4 Aug 1998 18:10:53 +0100
From: "chris.swinson" <chris.swinson-at-zetnet.co.uk>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Fw: Input frequency (fwd)
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: 04 August 1998 07:17
Subject: Re: Fw: Input frequency (fwd)
>
>
>---------- Forwarded message ----------
>Date: Mon, 03 Aug 1998 12:24:50 -0700
>From: Jim Lux <James.P.Lux-at-jpl.nasa.gov>
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: Re: Fw: Input frequency (fwd)
>
>Tesla List wrote:
>>
>> ---------- Forwarded message ----------
>> Date: Sun, 2 Aug 1998 12:50:09 +0100
>> From: "chris.swinson" <chris.swinson-at-zetnet.co.uk>
>> To: tesla list <tesla-at-pupman-dot-com>
>> Subject: Fw: Input frequency
>>
>> -----Original Message-----
>> From: chris.swinson <chris.swinson-at-zetnet.co.uk>
>> To: tesla list <tesla-at-pupman-dot-com>
>> Date: 01 August 1998 22:09
>> Subject: Input frequency
>>
>> Hi All,
>>
>> Say if you had a Neon say, 10Kv at 50ma running on the usual 230V 50Hz
>> mains. As far as I can gather if you use 230V input but at 100Hz you
would
>> actually get 20Kv at 50ma, thus more wattage input. Has anyone tried
this.
>> It may stress the Neon transformer but would this work ?
>
>Actually, no, you'd get 10 kV at half the current, 25 mA. The unloaded
>output voltage is determined by the turns ratio and the input voltage,
>which didn't change in your example, so the output voltage would remain
>unchanged. The output current for a neon transformer is limited by the
>equivalent of a large series inductor. The impedance of that inductor is
>proportional to frequency, i.e. twice the impedance at twice the
>frequency. Since it is in series, with the same voltage, the current
>will be halved.
>
I'd assume as there would be a greater surge in the primary, it would
reflect in the secondary as well. If you apply DC to a 230 V primary that
draws say 3 amps at 50Hz, and raise the voltage the coil draws masses more
power. I assume that it would do the same for a Neon tranformer as well.
I tried this on a small scale once with a 12 coil that stepped to 230 v. I
was still running at 12 V ( well 10 in fact ) and as I rasied the frequency
higher and higher I got small sparks off , yes, 230 V. These were only in
the mm range but it was sure enough more than 230V. Ok, it may not be more
voltage, I don't know.
It could be doubleing the voltage and halfing the current which seams the
best explination. but If I can get say 2Kv from a 230V transformer, what
could I get from a 8Kv transformer ?
I don't know how this will effect the currnet of the coil ( if at all )
thats why I'm asking you guys to see if anyone know !
chris.swinson-at-zetnet.co.uk
thanks !
>
>>
>> Also does any one know of a 230V adustable frequency circuit ? I treid
to
>> think up one, It would entale half wave recitfier on the mains with a cap
to
>> give about 230 V DC. Then switch it using power mosfets using a 555
timer
>> to alter the frequency. It would be nice if some one had such a design
>> before I try my idea ( I'm not very bright in mosfet designs, essp power
>> circuits :-( )
>What you describe is known as an inverter. For higher power uses they
>are popular as motor speed controls to generate variable frequency (and
>voltage) 3 phase power to drive an induction motor. Inverter circuits
>are simple in theory, but hard to make work reliably and efficiently in
>practice, although getting one to work at a single frequency/load
>combination is somewhat easier. This is particularly so, when you drive
>inductive loads (as you are contemplating) or in a high EMI environment
>(which anywhere near a tesla coil is).
>
>