nikisalli

modified 8 years ago

Question about PLL

156

02:17:53

Can that potentiometer on the LPF actually change the phase shift from input to output? I see someone does that on PLL based tesla coils

published 8 years ago

hurz

8 years ago

Yes it can, cause its injecting some current into the loopfilter which will cause a phase error which the PLL will try to compensate!

nikisalli

8 years ago

That's awesome! But i can't see any change in EC does it change the phase difference by only a few degrees?

zf121

8 years ago

Cool!

zf121

8 years ago

I've not made a very powerful sstc yet

hurz

8 years ago

Yes, the current is very small, 10k against 400Ohm from phase detector. Decrease poti resistance and 10k fixed one. But do not overstress it, cuz the PLL is in dangerous to unlook!

nikisalli

8 years ago

Ok thanks

hurz

8 years ago

Do you need the divider? I would do it without it to get +90°/-90° phase shift. What target frequency do you run the tesla coil? 400kHz?

nikisalli

8 years ago

220Khz. I want to reach zero current switching to make my IGBTs happy

hurz

8 years ago

Here a simple PLL setup for phase control by voltage http://everycircuit.com/circuit/4958457675644928

nikisalli

8 years ago

Thank you a lot! I'm going to try this on my tesla coil. I'm using cd4046 as PLL oscillator

hurz

8 years ago

I can try it with 555 on a breadboard tomorrow

nikisalli

8 years ago

I'm building the new pll right now

hurz

8 years ago

I run out 4046 😩

nikisalli

8 years ago

No problem i just need to make this phase changer to get ZCS on my tesla coil's half bridge

nikisalli

8 years ago

It works! I've made a new pll and it can adjust it's phase shift from the feedback! Now i'm going to test this in the tesla coil

hurz

8 years ago

Cool

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