
Originally Posted by
Floris
As said, with this coil I use the cap-diode modification. The capacitor in the trigger circuit has the function of boosting the trigger signal to the base. It will run without a capacitor and charge batteries but choosing the right capacitor for the setup and batteries will really add to the amplitude of the spikes and can increase or decrease the running frequency. My tests with only one MLJ21194 showed me to use quite a small cap like .22uf. It gives the highest frequency and good charging. The drawback I found when further increasing current you start to see ringing on the base just before the cap discharges. Charging is still good but I need to explore that more. My exploration of the coil is far from finished but sometimes the .22uf is to small and 1uf works well. With 8 transistors anything bigger than 4.7uf seemed too big.
I must add here that I have been testing a fair bit with front and back in parallel not in series. That totally changes the behavior of the setup. With the all batteries connected in parallel charging is really strong, however, tuning a nightmare. It is very sensitive to the SOC of the batteries. Input current will cut in half after sometime. Both front and back impedance changes are at work here, I believe. Also duty cycle is much lower, in the area of 20%. The frequency will go up with increased input power, whereas in series config the frequency will go down with increased power (although in other SS coils I have also seen increases, in line with Patrick's builds?).
There is a lot to explore here, admittingly I may have focused too much on the back end of this. It appears that with batteries in parallel the primary is draining much faster than in series config. I need to do the runs and get the numbers but it was certainly different.
Please ask me any question you have. Hope I'm not boring people with sharing my endeavors.
More soon.
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