Re: bridged ignition coils

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Stephen Conner by way of Terry Fritz <teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>

At 07:34 01/05/03 -0600, you wrote:
>Original poster: "Jolyon Vater Cox by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
>
>I am enquiring as to the possibility of driving a couple of ignition coils 
>off an H-bridge
>with  LT inputs in anti-parallel and the HT outputs in series
>so that the total HT voltage is doubled.
>Can this be done, and is it a good technique -or don't ignition coils work 
>so well in this configuration?

Connecting two ignition coils like this doesn't seem to be a problem. With 
ordinary coils that have 3 terminals, the secondary is connected internally 
to the (-) end of the primary. So when you connect the primaries in 
anti-parallel you connect the cold ends of the secondaries together as 
well. You could also connect the primaries in series, hooking the two (-) 
terminals to each other, and driving the two (+) terminals. Either way, you 
end up with a centre-tapped HT output like an NST.

I don't know about the drive circuit though. You need hundreds of volts 
going into the primary. The best results seem to be with circuits that 
charge a capacitor off the mains to about 300-600 volts, and then dump it 
into the primary/ies by firing a thyristor. This circuit can deliver 
hundreds of watts and generate some spectacular arcing. However, the HT 
output is in the form of a high frequency oscillation which might not be so 
good if you want to rectify it. An ordinary flyback driver circuit might be 
better in this case. A H-bridge might work too, but it seems to be untried.

Steve C.