CDI systems info wanted

[Arnaud Westenberg]

Carter Shore wrote:
> 
> Arnaud,
> 
> There are some schematics of older CDI boxes out
> there, that utilize only a couple of transistors, and
> no IC's to produce a simple and reliable CDI function.
> The simplicity of these systems allows easy analysis
> of the the fundamental CDI operation. Attaching a
> scope (with suitable HV probe) while operating is very
> revealing.

Do you have any pointers to those schematics so I can study a bit more?
The simplicity of the schematics would really get me started :-)
 
> I'm not quite sure what advantage you seek by
> eliminating the capacitor. It's an integral part of
> the system's operation.

My idea was instead of discharging a capacitor into the primary of the
coil, directly feeding the primary of the coil with an HV AC power
supply. This would eliminate the ringing of the capacitor/coil combo and
spark duration would be as long as one feeds the coil from the power
supply. It's just an idea of a Mechanical engineer and I don't know if
it can be realized due to the power requirements, maybe the power supply
would be huge.
 
> A single high voltage (400-600 V) power inverter can
> easily supply enough energy to run several different
> capacitor/SCR/coil sets, one for each spark plug. This
> gives the simplicity and economy of a single HV power
> stage, with the flexibility and fine control of
> individual distributorless triggering.

I see, but where do I look for information about how these power
inverters operate and their construction? Would it be possible to build
such a circuit wich directly powers the primary of the coil instead of
charging a capacitor?
 
Thanks again,

Arnaud
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