I am trying to couple a high voltage transformer (automobile coil) 220 V to 10 kV, with a low voltage home made transformer 220 V to 6, 12 V (think MOT but bigger).
I have tested/used the LV transformer for spot welding so I know that it outputs a lot of current, upwards of 1000 A. The HV transformer (auto coil) is being driven by a fan regulator (Triac) so it outputs somewhere around 10 kV that run through my homemade 15k capacitor. I can see the high voltage output jump the spark gap1 (3–4 mm wide).
I have coupled these in series via a 27:30 turn coupling coil wound around ferrite rod as shown in the image below, one side of LV runs through the coil and the other side makes ground. There is a small gap (spark gap2) where they meet and I can see the spark in this gap also when I turn on the HV circuit.
I was expecting to see a large increase in current through this gap (gap2) when I turn on the LV transformer, as spark through the gap will produce plasma which will make the gap behave like a short, so high current from LV transformer will get added in series and spark will be much bigger, just like a welding machine. But I do not see any increase in current when I turn on the LV transformer while HV is sparking through gap2.
I have tried to turn on both together with same switch, still size of spark is small, as if only HV transformer is running. Turing on LV transformer has no effect at all. My LV transformer is center tapped and I have tried with both 6 and 12 V tap, still I see not effect. What am I missing here?