Re: Re: [TCML] op amp wiring

[DC Cox <resonance@xxxxxxxxxxxx>]

Some flybacks have gapped cores, while some do not.

With a gap as small as .004 inches, like we use, it may be difficult to
determine if you are using a gapped core
reactor, unless each flyback is purchased new, like we do.

The gapped core design helps prevent excessive sec currents.  In the case of
a Tesla coil oscillator, flyback driven, a non-gapped core
reactor is preferably as it can deliver larger peak currents in the sec coil
of the flyback.  With plasma sphere operation this type is not
the best one to use, and the gapped core design is safer to use as it
delivers less current.

Dr. Resonance




On Sat, Jan 17, 2009 at 10:50 AM, Antonio Carlos M. de Queiroz <
acmdq@xxxxxxxxxx> wrote:

> Ed Phillips wrote:
>
>> <div class="moz-text-flowed" style="font-family: -moz-fixed">    ALWAYS
>> use a buffer amplifier between the NE555 and the base of a power transistor
>> in the primary of a flyback [or ignition] transformer.
>>
>> Certainly. A 555 can only output about 200 mA. Another problem is a big
> waste of power in a driver using a resistor at the base of the power
> transistor.
> Here are some of my flyback experiments:
> http://www.coe.ufrj.br/~acmq/flyback/
> The second driver uses an inductor to drive the transistor without waste of
> energy.
> A thing that I see in several citations of flyback drivers is that they
> show resonances at a few tens of kHz. I can't observe any significant
> resonance in my flybacks. But there is something that looks as a
> "resonance", but isn't. The switching transistor takes some time to get
> switched off. If the driver switches it off and then on again without
> waiting for this minimum time, the transistor doesn't switch off, and the
> current trough the primary coil rises to twice the normal value. With the
> increased current, the transistor switches off at the next command from the
> driver, for some reason. When this happens, a sudden increase in the output
> voltage appears, looking as a sharp resonance. If the frequency is further
> increased, the maximum primary current decreases, and the output voltage
> decreases. The false resonance appears again when the transistor doesn't
> switch off for three periods, four periods, etc.
> The (very fragile) oscillator with a bipolar transistor works with a mosfet
> too. The two resistors can have higher resistance, and something shall be
> added to avoid excessive negative voltage at the mosfet gate.
>
> Antonio Carlos M. de Queiroz
>
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