My First DRSSTC
RogerInOhio, Sat Jul 28 2018, 01:00AMLast summer Bud Mohrman gave me a DRSSTC driver controller of the type thats on Steve Wards web site and with that and a little advice I finely got around to building a full bridge DRSSTC. I will list all the specs and post pictures here. Maybe some of you can make suggestions because I know this thing could be a better performer.
At 220 volts input I can get 23 inch sparks but when I run the voltage that high the IGBTs blow up frequently. In the pictures it is running at about 160 volts input and getting 12 inch sparks. One thing I know I did poorly was in keeping the electrical connections in the bridge circuit as short as possible. Here are some specs.
Resonant frequency 70 khz, Primary capacitor .1uf at 10kv Primary turns 10
IGBT s G40N60B3 with external flywheel diodes
Interrupt rate 260 Bps On time 100us (use signal generator as interrupter)
Re: My First DRSSTC
Sulaiman, Sat Aug 11 2018, 11:05AM
That looks like a nice TC.
I'd be proud of it !
I've only built SGTCs and mosfet-destroying SSTCs so I can't help much.
Sulaiman, Sat Aug 11 2018, 11:05AM
That looks like a nice TC.
I'd be proud of it !
I've only built SGTCs and mosfet-destroying SSTCs so I can't help much.
Re: My First DRSSTC
RogerInOhio, Fri Aug 17 2018, 12:55AM
Thanks for the kind words. I got plans to try to improve it. So far I have been pleased that it works at all.
RogerInOhio, Fri Aug 17 2018, 12:55AM
Thanks for the kind words. I got plans to try to improve it. So far I have been pleased that it works at all.
Re: My First DRSSTC
zilipoper, Thu Aug 23 2018, 11:54PM
Hello Roger I'm glad you continue to engage in Tesla coils
How to live your biggest vacuum tube coil?
Now you've moved on DRSSTC
zilipoper, Thu Aug 23 2018, 11:54PM
Hello Roger I'm glad you continue to engage in Tesla coils
How to live your biggest vacuum tube coil?
Now you've moved on DRSSTC
Re: My First DRSSTC
brtaman, Sun Sept 02 2018, 12:29PM
Hi Roger,
It has been a while since I had a running DRSSTC, but I seem to remember that playing around with the coupling made a noticeable difference in performance.
It is hard to tell, but from the looks of it, it seems as though your coupling is on the low side? I would also look at playing with the on time and interrupt rates.
However, I believe you likely have some ringing and other issues due to your bridge cooling setup (great use of those old CPU coolers :), it would cool great in a SSTC setup, however it is likely causing issue due to the much higher switching currents. I think you would help your reliability considerably, if you can get those IGBT's close together.
Here is an old video of mine, it used a slow Gen 1. IGBT, I was able to push the spark and amperage by running longer on-times and with a pretty high coupling. However, this was one of those half-bridhe bricks so the leads were minimized from the factory.
Regards,
Rok
PS: Still remember your great VTTC from youtube, and it has been years. :)
brtaman, Sun Sept 02 2018, 12:29PM
Hi Roger,
It has been a while since I had a running DRSSTC, but I seem to remember that playing around with the coupling made a noticeable difference in performance.
It is hard to tell, but from the looks of it, it seems as though your coupling is on the low side? I would also look at playing with the on time and interrupt rates.
However, I believe you likely have some ringing and other issues due to your bridge cooling setup (great use of those old CPU coolers :), it would cool great in a SSTC setup, however it is likely causing issue due to the much higher switching currents. I think you would help your reliability considerably, if you can get those IGBT's close together.
Here is an old video of mine, it used a slow Gen 1. IGBT, I was able to push the spark and amperage by running longer on-times and with a pretty high coupling. However, this was one of those half-bridhe bricks so the leads were minimized from the factory.
Regards,
Rok
PS: Still remember your great VTTC from youtube, and it has been years. :)
Re: My First DRSSTC
RogerInOhio, Mon Sept 03 2018, 12:23AM
Thanks for the suggestions. In planing to build a new driver soon. The heat sinks I am using now are definitely an overkill as they don't even get warm when the coil is running so I'm going to work on getting everything closer together.
RogerInOhio, Mon Sept 03 2018, 12:23AM
Thanks for the suggestions. In planing to build a new driver soon. The heat sinks I am using now are definitely an overkill as they don't even get warm when the coil is running so I'm going to work on getting everything closer together.
Re: My First DRSSTC
Blackcurrant, Tue Sept 04 2018, 02:15AM
ISOPLUS247 IGBTs are quite handy as you can mount them on the same heatsink say two of them using gull wing clips.
here's some thoughts
if you use a very sharp break out point it will only come from there and the streamers will be shorter, maybe try a small round bit on the end of it.
are you sure you have it tuned well having anything like that ball above will easily put it out of tune if not set up/tuned with it in place?
the lower end of the secondary is it on a good ground?
protection diodes on the IGBTs gate?
could your sig gen signal be getting messed with you have some long leads there
you may find there is a lot of noise getting back into the mains wiring, filters?
anyway hope some of this mad rambling may throw up some ideas
Blackcurrant, Tue Sept 04 2018, 02:15AM
ISOPLUS247 IGBTs are quite handy as you can mount them on the same heatsink say two of them using gull wing clips.
here's some thoughts
if you use a very sharp break out point it will only come from there and the streamers will be shorter, maybe try a small round bit on the end of it.
are you sure you have it tuned well having anything like that ball above will easily put it out of tune if not set up/tuned with it in place?
the lower end of the secondary is it on a good ground?
protection diodes on the IGBTs gate?
could your sig gen signal be getting messed with you have some long leads there
you may find there is a lot of noise getting back into the mains wiring, filters?
anyway hope some of this mad rambling may throw up some ideas
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