Uploaded December 2023 | Updated September 2026, 2 weeks ago
I have a couple more of these using the schmitt trigger oscillator running at around 3Mhz and those seemed like they were less picky about shielding and tuning. This circuit didn't want to give me a consistent and reliable frequency tune until I did all the shielding. It's actually tuned closer to 4.3Mhz but I'm able to get away with running a little over 4.5Mhz at 50V without much problems by cheating a little with higher coupling. I had the best results with a build using a CD4046 for the VCO at 2.8Mhz and a UCC27322. I still need to try using the schmitt trigger as the BG oscillator with a separate input taking some kind of feedback.
The IXDD630 is pretty amazing so I figure for the effort it would take to create multiple stages of amplification to build a 4-5Mhz resonant drive using discrete switches I might as well use a 10 dollar gate driver. I've already seen a little over 5Mhz plasma doesn't really look so much different from maybe 3Mhz, so if I can tune for 7Mhz and don't see any difference I might as well go back down to about 4Mhz and go higher power. This is supplying the driver with only about 12.5VDC though I did have it closer to 15V in the video and didn't even notice.
Normally I seem to tune these to run at around 45V max which places the drain swing at around 180-200V on a 200V fet. With this one it really needs more like 100VDC so it will eventually have to run if off the variac.
I have a couple more of these using the schmitt trigger oscillator running at around 3Mhz and those seemed like they were less picky about shielding and tuning. This circuit didn't want to give me a consistent and reliable frequency tune until I did all the shielding. It's actually tuned closer to 4.3Mhz but I'm able to get away with running a little over 4.5Mhz at 50V without much problems by cheating a little with higher coupling. I had the best results with a build using a CD4046 for the VCO at 2.8Mhz and a UCC27322. I still need to try using the schmitt trigger as the BG oscillator with a separate input taking some kind of feedback.
The IXDD630 is pretty amazing so I figure for the effort it would take to create multiple stages of amplification to build a 4-5Mhz resonant drive using discrete switches I might as well use a 10 dollar gate driver. I've already seen a little over 5Mhz plasma doesn't really look so much different from maybe 3Mhz, so if I can tune for 7Mhz and don't see any difference I might as well go back down to about 4Mhz and go higher power. This is supplying the driver with only about 12.5VDC though I did have it closer to 15V in the video and didn't even notice.
Normally I seem to tune these to run at around 45V max which places the drain swing at around 180-200V on a 200V fet. With this one it really needs more like 100VDC so it will eventually have to run if off the variac.
