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Re: Flyback Coil system
Tesla List wrote:
>
> Original Poster: "Coiler" <mycroft-at-access1-dot-net>
>
> I admit to my lack of knowledge when it comes to these systems, but I
> thought
> it would be fun to build one, since I found myself with a flyback from
> an old CGA monitor that was lying around the shop. (most now on its
> way to the landfill)
> So I build the (in)famous 3055 based flyback driver, and it works just
> fine - getting 3/4" solid arc (corona out to about 1"). The problem
> is that the 3055s are getting *HOT* as is the 3A bridge that is feeding
> the circut. <SNIP, SNIP>
--------------------------------------------------
Mike
I built the same circuit about 15 years ago when it first appeared
in Radio & Electronics. With most garden variety flyback xfmr's,
resonant frequency is in the 20-40Khz range, and the circuit tends to
work in Class 'B' (the output waveform when viewed through an 'E' field
probe is sinusoidal). Since the transistors are not being hard driven,
they tend to run HOT. Options:
1. Force air cool the heatsink.
2. Run normal air convection and limit run times ( :^C ).
3. Parallel multiple transistors by placing a 0.1 ohm non-inductive
resistor in each emitter to ground (-), and placing 2 or 3
'3055's in parallel on each side of the transformer to allow higher
current in primary.
Also watch input voltage, the limit will be the flyback HV standoff
(input to transistor(s) could be pressed as high as maybe 24 volts,
since they are 60 volt devices).
My circuit running at 16-18 volt input would drive a clear plasma globe
and input current was 3-4A range (50-75W input). A neat, simple
circuit for building during the holiday's. :^)
OBTW, this is the simplest incarnation of a SSTC.
Regards
DAVE SHARPE, TCBOR