Induction Coil Cap Discharger ( was: No Terry Filter)

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Original poster: Kurt Schraner <k.schraner@xxxxxxxxxxx>

Hi Paul Brodie, all,

...well, slightly OT. I've buildt a modified version of Ed Phillips's 
DC-resonant induction coil driver. The schematic diagram can be had at:

http://home.datacomm.ch/k.schraner/Cap_discharger_EdP8.jpg

The main differences to Ed's driver are:
1.) Having 230V/50Hz AC in Europe, no voltage doubler is needed.
2.) Instead of the Quadrac, a thyristor + anti-diode is used.
3.) An RC snubber had to be added to the thyristor, in order to
    prevent shoot-through of the thyristor.
4.) Power 10ohm/100W resistor, limiting shoot-through current, added.
5.) 6.3A fast blow fuse.
6.) Dimmer for voltage control (for inductive load; dimmer optional!)
7.) High discharge capacitor value of seriesed 2x40uF/400V caps = 20uF

Main problem, is to find a non-saturating charging-inductor. As can be 
seen, the value of it is not critical (Ed's 6H vs my 0.26H). This driver is 
much friendlier to your AC-line network, regarding pulse generating 
disturbances, than a simple dimmer induction coil driver. Another benefit 
is the variable discharche frequency (~BPS). The value of the discharge 
capacitor may be adapted to the power needed (my 20uF are for power 
induction coils). A 25cm (10") spark on one of my bigger induction coils 
may be seen:

http://home.datacomm.ch/k.schraner/DSCN1723.JPG

My current realization of the driver may be had at:

http://home.datacomm.ch/k.schraner/DSCN1724.JPG

I'm quite happy with this induction coil driver, which is properly working 
now. And I think, it's much easier to control the operation of an induction 
coil by storing the bang energy in a capacitor, than in conventional 
interruptor mode, in the inductance of the primary.

Best regards,
              Kurt

Tesla list schrieb:
> Original poster: "Paul B. Brodie" <pbbrodie@xxxxxxxxxxxxx>
> Ed,
> Do you have a design for a resonant charging driver for ignition coils? I 
> have been wanting to do this but I haven't seen any examples where someone 
> else has done it. So far, I have run my coils with a dimmer and 2 MO caps 
> in parallel (1.95 mF total) and with a 555 wired as an astable 
> multivibrator running between approximately 200Hz and 1000Hz.  I'm 
> probably crazy but what I had in mind is using a MOT with a voltage 
> doubler driving a resonant charger and cap using either a spark gap or 
> SIDACs to discharge the cap through the primary of the ignition coil. 
> Peter Terren has an example of driving an ignition coil with a MOT and 
> SIDACs on his site. I would appreciate any advice.
> Paul
> Think Positive