Re: PIRANHA-III Power control? (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sun, 17 Dec 2006 09:11:59 -1000
From: Chester Lowrey <hilo90mhz@xxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: PIRANHA-III Power control? (fwd)

Hi,

Just a few weeks ago I built a kiln for melting aluminum and various other
things.. And had a similar problem about how to control the power. My
solution was to modify an existing 600W lamp dimmer circuit which had a
triac inside. If you take apart the case its easy to just desolder the
existing TO-220 case triac and connect something larger.. In my case a
recycled microwave oven triac, I also replaced the small inductor that was
on the PCB with something larger and none of the high current travels
through the PCB anymore. I know the circuit is very simple and you can put
one together from scratch, but for me it was easier to just take apart the
lamp dimmer as they are readily available and cheap.. Oh and mine is
switching an 1800 Watt resistive load at 120Volts..

One question I have is whether these simple trigger DIAC based circuits will
work with reactive loads?

Here are a few pics
Just the power controller:
http://hilo90mhz.hungrychild.org/projects/furnace/DSC07702.jpg
Power controller and furnace:
http://hilo90mhz.hungrychild.org/projects/furnace/DSC07705.jpg


Chester

On 12/16/06, Tesla list <tesla@xxxxxxxxxx> wrote:
>
> Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Sat, 16 Dec 2006 19:08:32 -0700
> From: Terrell Fritz <terrellfone@xxxxxxxxxxxxxxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: PIRANHA-III  Power control?
>
> Hi,
>
> I am working on PIRANHA III issues today.  A dual MOT system that runs off
> a 120VAC 20A circuit with ease.  It is in the 8 foot arc to ground
> range...  About 2kW input at ~90% efficiency.
>
> These coils like to run with the MOT input voltage at about 95-105 volts
> to
> stay out of the MOT saturation range which just waists precious
> current.  Normally that is done with a 15 -20 amp variac...
>
> http://drsstc.com/~piranha/PIRANHA/PIRANHA-3/PIRANHA-III-001.gif
>
> Variacs are very nice, but they are real heavy and not real "modern" or
> solid state.  The charging circuit (MOT / Primary Cap loop) is resonant
> too
> to drive up to a 15000 volt firing voltage...  But the waveforms are
> pretty
> "tame" and the power factor is excellent without any fiddling.
>
> http://drsstc.com/~piranha/PIRANHA/PIRANHA-3/PIRANHA-III-002.gif
>
> It would be super cool to use a beefy lamp dimmer circuit or some similar
> cheap but very reliable solid state thing to control power other than the
> variac.  The PIRANHA input section is very forgiving of sloppy input wave
> forms and all so no big deal there.  Ceiling fans are made for inductive
> loads...
>
> I don't know much about dimmer circuits and such so I can't guess at what
> to do and feed the computer models well.  0:-|
>
> If anyone knows what to do to make a cheap hardy dimmer type circuit that
> could run two MOTs (~2kW)  I am all ears ;-))
>
> Cheers,
>
>         Terry
>
>
>
>
>