# Tesla Coil help. Trouble with resonant freq

#### nissan20det

Joined Apr 3, 2015
69
Hey guys, So I started building Tesla coils last week. I got my first one to work but now, of course, I wanna go bigger. Now before I do this I wanna make sure I can successfully tune may small 30V one first(No HV step). So I started using some calculators online. Im getting like 2180khz as my outcome. My coil is 1.31in diameter, 582 turns of 30 gauge wire. I measured wire as .0104in including enamel coating. Doesn't that seem high? well my real issue right now is when making an LC circuit and viewing on my scope I don't see a distinct rise or fall as freq increases or decreases. So I saw on youtube if you have a two channel scope to add a resistor in series with your freq gen input and attach one prob before resistor and one after. I did this and I can see a distinct phase shift so I centered the shift and got 11.7khz. That is quite a bit away from 2180Khz. So am I doing this wrong I also noticed if I change resistance value that shift point is way different so i gotta be doing something wrong here.

I attached a picture of how I wired this, I tried a 220,100,56ohm resistor with a .1uf cap. I don't have a freq gen so I was using audacity program on my computer. but I only get up to a 20khz signal. my scope has a out sig as well but in sign wave it also only goes to 20k but its not linear 10, 20, 50, 100, 200, 500, 1k, 2k, 5k, 10k, 20k

Another couple questions I have, How do I test resonance for my primary. They are so short and heavy gauge my signal just gets depleted. Must be pulling to much current. Another is how would I test the output voltage of a DC fly-back? I have a 60Kv old probe that doesn't even budge and I tried my Fluke 80K-6KV on my meter and it read .256v which converts to 256V but I know this fly-back is at least 8kv.