slash128 first DRSSTC build
slash128v6, Sun Jul 23 2017, 09:31PMGreetings, I have been lurking, reading and building my first DRSSTC. I have a number of classic spark gap coils under my belt. For this build I wanted it to be medium power, durable and nice looking. I more or less copied LoneOceans DRSSTC 3 design, but using Phillip Slawinski's UD+ driver. IGBTs are CM300DY-24H. I have everything but the secondary together at this point. I will post up more details and photos as I get time. At the moment I am trying to verify the primary is all operating correctly, but a little confused on how to properly take scope readings for phase lead adjustment. I have the bridge powered via a variable isolation transformer. With my scope attached to the bridge output I get a sine wave, where it seems others see a square wave. I am using a cascaded 32:1:32:1 CT for monitoring primary current with a 5.1 ohm burden resistor, but the output is very low, in the mV range. Am I taking signal readings at the wrong locations?
Re: slash128 first DRSSTC build
slash128v6, Sun Jul 23 2017, 09:32PM
Some shots of the coil itself.
slash128v6, Sun Jul 23 2017, 09:32PM
Some shots of the coil itself.
Re: slash128 first DRSSTC build
slash128v6, Sun Jul 23 2017, 09:37PM
Some shots of the coil itself:
slash128v6, Sun Jul 23 2017, 09:37PM
Some shots of the coil itself:
Re: slash128 first DRSSTC build
slash128v6, Mon Jul 24 2017, 10:29PM
So it seems the primary is not oscillating after getting the initial startup pulses from the driver. Wondering if anyone has any advice. I've scoped the primary LC circuit for resonant frequency and confirmed it is at 72KHz, which is what the driver startup oscillator is configured for. The bridge gets the initial two startup pulses but then it does not fire up and run on its own feedback.
slash128v6, Mon Jul 24 2017, 10:29PM
So it seems the primary is not oscillating after getting the initial startup pulses from the driver. Wondering if anyone has any advice. I've scoped the primary LC circuit for resonant frequency and confirmed it is at 72KHz, which is what the driver startup oscillator is configured for. The bridge gets the initial two startup pulses but then it does not fire up and run on its own feedback.
Re: slash128 first DRSSTC build
johnf, Tue Jul 25 2017, 06:44AM
Hope you have not got that pot in the center when you were trying it out.
Massive Q killer ie shorted turn.
Or are you trying to make an induction heater???
johnf, Tue Jul 25 2017, 06:44AM
Hope you have not got that pot in the center when you were trying it out.
Massive Q killer ie shorted turn.
Or are you trying to make an induction heater???
Re: slash128 first DRSSTC build
slash128v6, Tue Jul 25 2017, 01:35PM
It is serving as a dummy load in place of the secondary.
slash128v6, Tue Jul 25 2017, 01:35PM
It is serving as a dummy load in place of the secondary.
Re: slash128 first DRSSTC build
slash128v6, Tue Jul 25 2017, 04:06PM
Looking like one or both of my IGBTs may be questionable. Any suggestions on how to thoroughly test them? I have done the 12V lamp test on both and they both seemed to respond as expected.
slash128v6, Tue Jul 25 2017, 04:06PM
Looking like one or both of my IGBTs may be questionable. Any suggestions on how to thoroughly test them? I have done the 12V lamp test on both and they both seemed to respond as expected.
Re: slash128 first DRSSTC build
slash128v6, Wed Jul 26 2017, 04:05PM
It works! I'm not sure what got it going. I tried one of my maxwell caps but that didn't work. I went through all the connections and still no change. I removed the 10K resistor from the bridge output but no change. I finally kept cranking the variac past 200. Around 250V I started hearing a crackling and seeing the familiar trace flickering on the scope. I kept going to 300V and it got stable. I let it run a bit and then backed the voltage down and it stayed stable all the way down to around 50V or so. I thought maybe it was the 10K resistor but I reconnected that and it still runs. All I can think of is there was some bad connection that finally burnt through. Everything looks nice and and shiny so I'm not sure what it was...
slash128v6, Wed Jul 26 2017, 04:05PM
It works! I'm not sure what got it going. I tried one of my maxwell caps but that didn't work. I went through all the connections and still no change. I removed the 10K resistor from the bridge output but no change. I finally kept cranking the variac past 200. Around 250V I started hearing a crackling and seeing the familiar trace flickering on the scope. I kept going to 300V and it got stable. I let it run a bit and then backed the voltage down and it stayed stable all the way down to around 50V or so. I thought maybe it was the 10K resistor but I reconnected that and it still runs. All I can think of is there was some bad connection that finally burnt through. Everything looks nice and and shiny so I'm not sure what it was...
Re: slash128 first DRSSTC build
futurist, Mon Jul 31 2017, 02:30PM
With 1:~1000 CT the driver should work even at 30VDC bridge voltage, I suggest you debug it before continuing
I do my first runs under 50VDC bridge voltage because then there is a very little risk of IGBT damage
How many startup cycles have you set?
Is fault led on? Try increasing interrupter frequency
futurist, Mon Jul 31 2017, 02:30PM
With 1:~1000 CT the driver should work even at 30VDC bridge voltage, I suggest you debug it before continuing
I do my first runs under 50VDC bridge voltage because then there is a very little risk of IGBT damage
How many startup cycles have you set?
Is fault led on? Try increasing interrupter frequency
Re: slash128 first DRSSTC build
slash128v6, Mon Jul 31 2017, 05:35PM
Thanks for the advice Fururist. Seems it was a bad connection in the primary circuit. I went over all the connections multiple times and finally it started up. I inspected them again looking for which one it might have been and one of the 4AWG crimp connectors to the primary slid off the wire with not much effort. I went back through them all again and pounded them tight with a sledge hammer. No issues starting up now :) I am still trying to get the phase lead adjusted. Adjusting the inductor I have doesn't seem to have any effect on the phase so I have ordered some others to test.
slash128v6, Mon Jul 31 2017, 05:35PM
Thanks for the advice Fururist. Seems it was a bad connection in the primary circuit. I went over all the connections multiple times and finally it started up. I inspected them again looking for which one it might have been and one of the 4AWG crimp connectors to the primary slid off the wire with not much effort. I went back through them all again and pounded them tight with a sledge hammer. No issues starting up now :) I am still trying to get the phase lead adjusted. Adjusting the inductor I have doesn't seem to have any effect on the phase so I have ordered some others to test.
Re: slash128 first DRSSTC build
futurist, Mon Jul 31 2017, 11:49PM
Can you post scope shots?
futurist, Mon Jul 31 2017, 11:49PM
Can you post scope shots?
Re: slash128 first DRSSTC build
slash128v6, Tue Aug 01 2017, 04:01AM
Here are some samples:
slash128v6, Tue Aug 01 2017, 04:01AM
Here are some samples:
Re: slash128 first DRSSTC build
futurist, Tue Aug 01 2017, 05:55PM
Switching spikes are almost 100% of the bridge voltage
I suppose you use 7M3-393, what is you gate resistance and did you install antiparallel diodes?
futurist, Tue Aug 01 2017, 05:55PM
Switching spikes are almost 100% of the bridge voltage
I suppose you use 7M3-393, what is you gate resistance and did you install antiparallel diodes?
Re: slash128 first DRSSTC build
slash128v6, Tue Aug 01 2017, 06:20PM
Actually, I am using a SLOT TEN-5-09. Some other feedback I got was that it might just be out of range. It does make an ever so slight adjustment if I zoom in very close, but it doesn't really do anything to reduce the spikes. I have some SLOT TEN-5-08 and SLOT TEN-5-10 on order to see if they have any better effect.
I am using 5.1 ohm gate resistors along with 1N5819 diodes.
slash128v6, Tue Aug 01 2017, 06:20PM
Actually, I am using a SLOT TEN-5-09. Some other feedback I got was that it might just be out of range. It does make an ever so slight adjustment if I zoom in very close, but it doesn't really do anything to reduce the spikes. I have some SLOT TEN-5-08 and SLOT TEN-5-10 on order to see if they have any better effect.
I am using 5.1 ohm gate resistors along with 1N5819 diodes.
Re: slash128 first DRSSTC build
futurist, Tue Aug 01 2017, 07:28PM
It all seems fine, it probably just needs other inductor
The coil looks great and I'm sure you could get 2m+ streamers from it!
I'm using 7M3-393 for my SKM400 brick (60 kHz), it's not ideal but works
Also, I noticed that some spikes disappear when I go to full voltage
futurist, Tue Aug 01 2017, 07:28PM
It all seems fine, it probably just needs other inductor
The coil looks great and I'm sure you could get 2m+ streamers from it!
I'm using 7M3-393 for my SKM400 brick (60 kHz), it's not ideal but works
Also, I noticed that some spikes disappear when I go to full voltage
Re: slash128 first DRSSTC build
slash128v6, Tue Aug 01 2017, 08:16PM
Thanks for the feedback and advice! I should have the other inductors this Thursday, so hopefully they will solve the issue :)
If I can get 2M+ streamers I will be very happy! I modeled this after LoneOceans DRSSTC3. I have built a number of classic spark gap coils but this is my first solid state coil, well, aside from a couple TinyTesla kits I built. Admittedly, there are many things that I just don't know if I am making a n00b mistake or having a real issue. I truly appreciate the help!
Oh, as an aside, I did notice that the ringing is minimal/nearly gone, as the current reaches maximum. Seems to be in line with LoneOceans Phase Lead tuning write-up, so maybe it is ok? I bet it could be a little better, but maybe not as bad as I was originally thinking...
slash128v6, Tue Aug 01 2017, 08:16PM
Thanks for the feedback and advice! I should have the other inductors this Thursday, so hopefully they will solve the issue :)
If I can get 2M+ streamers I will be very happy! I modeled this after LoneOceans DRSSTC3. I have built a number of classic spark gap coils but this is my first solid state coil, well, aside from a couple TinyTesla kits I built. Admittedly, there are many things that I just don't know if I am making a n00b mistake or having a real issue. I truly appreciate the help!
Oh, as an aside, I did notice that the ringing is minimal/nearly gone, as the current reaches maximum. Seems to be in line with LoneOceans Phase Lead tuning write-up, so maybe it is ok? I bet it could be a little better, but maybe not as bad as I was originally thinking...
Re: slash128 first DRSSTC build
slash128v6, Tue Aug 01 2017, 08:22PM
Here's the shot from LoneOcean's write-up that I am comparing to. At the beginning of the cycle, where current is just starting to build, the spikes are huge, but as current reaches maximum they are pretty much gone. Looks similar in my scope shot, no?
slash128v6, Tue Aug 01 2017, 08:22PM
Here's the shot from LoneOcean's write-up that I am comparing to. At the beginning of the cycle, where current is just starting to build, the spikes are huge, but as current reaches maximum they are pretty much gone. Looks similar in my scope shot, no?
Re: slash128 first DRSSTC build
slash128v6, Tue Aug 01 2017, 11:42PM
BTW- Shout out to Phillip Slawinski for putting up with my questions and n00bness! I really appreciate all the help :)
slash128v6, Tue Aug 01 2017, 11:42PM
BTW- Shout out to Phillip Slawinski for putting up with my questions and n00bness! I really appreciate all the help :)
Re: slash128 first DRSSTC build
futurist, Wed Aug 02 2017, 02:23AM
Phil helped me a lot with midi interrupter, I also say big thanks to him!
Yesterday I finally upgraded my coil to UD+, so far looks nice but I still didn't test it
Take a look at bridge output I scoped today, voltage was around 110V with 3 startup cycles
There is some ringing but it looks ok, I don't have any other inductors to try, gate resistance is 4.7 ohm which seems to work best
I think your output is more similar to
futurist, Wed Aug 02 2017, 02:23AM
Phil helped me a lot with midi interrupter, I also say big thanks to him!
Yesterday I finally upgraded my coil to UD+, so far looks nice but I still didn't test it
Take a look at bridge output I scoped today, voltage was around 110V with 3 startup cycles
There is some ringing but it looks ok, I don't have any other inductors to try, gate resistance is 4.7 ohm which seems to work best
I think your output is more similar to
Re: slash128 first DRSSTC build
slash128v6, Wed Aug 02 2017, 05:46PM
You're probably right regarding my output, just my wishful thinking lol...
Forgive my inexperience but how are you getting so many pulses, is that from the duty cycle of the interrupter? Mine stops after 6 or so cycles but you see more than double. I am not hitting OCD. I am using the SD Interrupter from OneTesla. Perhaps I can just increase the on_time in the code and reflash it?
slash128v6, Wed Aug 02 2017, 05:46PM
You're probably right regarding my output, just my wishful thinking lol...
Forgive my inexperience but how are you getting so many pulses, is that from the duty cycle of the interrupter? Mine stops after 6 or so cycles but you see more than double. I am not hitting OCD. I am using the SD Interrupter from OneTesla. Perhaps I can just increase the on_time in the code and reflash it?
Re: slash128 first DRSSTC build
futurist, Wed Aug 02 2017, 07:43PM
I was just finishing installing UD+ and did low power runs with dummy load like you
The current didn't seem to rise so fast so I changed prescaler in firmware for max. 300us on-time, but usually you run a coil at much lower on-times
futurist, Wed Aug 02 2017, 07:43PM
I was just finishing installing UD+ and did low power runs with dummy load like you
The current didn't seem to rise so fast so I changed prescaler in firmware for max. 300us on-time, but usually you run a coil at much lower on-times
Re: slash128 first DRSSTC build
slash128v6, Wed Aug 02 2017, 08:17PM
Cool. What driver did you change from, UD2.7? I think I'll see how the new inductors do tomorrow and then try to run it up at higher power and see how it does.
slash128v6, Wed Aug 02 2017, 08:17PM
Cool. What driver did you change from, UD2.7? I think I'll see how the new inductors do tomorrow and then try to run it up at higher power and see how it does.
Re: slash128 first DRSSTC build
futurist, Wed Aug 02 2017, 09:19PM
UD2.7
futurist, Wed Aug 02 2017, 09:19PM
UD2.7
Re: slash128 first DRSSTC build
Mads Barnkob, Thu Aug 03 2017, 08:29AM
Swtiching spikes are always much bigger in ratio to the input voltage when you are testing at low voltage, since the IGBT capacitances are the same, but as Vce gets higher and higher, the switching spikes will look acceptable, as they always were, it just looks more dramatic at low voltages
Mads Barnkob, Thu Aug 03 2017, 08:29AM
Swtiching spikes are always much bigger in ratio to the input voltage when you are testing at low voltage, since the IGBT capacitances are the same, but as Vce gets higher and higher, the switching spikes will look acceptable, as they always were, it just looks more dramatic at low voltages
Re: slash128 first DRSSTC build
slash128v6, Thu Aug 03 2017, 06:05PM
Thanks Mads! I should have new inductors today, so hopefully I can crank it up :)
slash128v6, Thu Aug 03 2017, 06:05PM
Thanks Mads! I should have new inductors today, so hopefully I can crank it up :)
Re: slash128 first DRSSTC build
slash128v6, Thu Aug 03 2017, 10:25PM
Mads: question for you: in one of your videos it looks like you are using the OneTesla SD Interrupter. Did you make any changes to the firmware for your coil?
slash128v6, Thu Aug 03 2017, 10:25PM
Mads: question for you: in one of your videos it looks like you are using the OneTesla SD Interrupter. Did you make any changes to the firmware for your coil?
Re: slash128 first DRSSTC build
slash128v6, Fri Aug 04 2017, 02:51AM
Good news: the SLOT TEN-5-10 worked perfectly for my coil!
Bad news: I blew my bus caps somehow... :(
slash128v6, Fri Aug 04 2017, 02:51AM
Good news: the SLOT TEN-5-10 worked perfectly for my coil!
Bad news: I blew my bus caps somehow... :(
Re: slash128 first DRSSTC build
slash128v6, Fri Aug 04 2017, 12:32PM
I panicked too much. After careful testing I found it wasn't the bus caps but the main rectifier.
Some video, still on lower power:
slash128v6, Fri Aug 04 2017, 12:32PM
I panicked too much. After careful testing I found it wasn't the bus caps but the main rectifier.
Some video, still on lower power:
Re: slash128 first DRSSTC build
slash128v6, Fri Aug 04 2017, 06:38PM
As an aside, "midget" style (10mm) fuse holders make great primary taps for 3/8 copper tubing.
slash128v6, Fri Aug 04 2017, 06:38PM
As an aside, "midget" style (10mm) fuse holders make great primary taps for 3/8 copper tubing.
Re: slash128 first DRSSTC build
futurist, Fri Aug 04 2017, 07:31PM
Nice ZCS!
I made similar tap point by soldering those fuse holders directly to 16mm^2 welding cable
Looks a bit ugly after many tunings
Beware that primary will get hot at higher current runs and melt those plastic clips
What did you use as rectifier?
futurist, Fri Aug 04 2017, 07:31PM
Nice ZCS!
I made similar tap point by soldering those fuse holders directly to 16mm^2 welding cable
Looks a bit ugly after many tunings
Beware that primary will get hot at higher current runs and melt those plastic clips
What did you use as rectifier?
Re: slash128 first DRSSTC build
slash128v6, Fri Aug 04 2017, 08:22PM
Nice! Yeah, I wasn't aware of how hot the primary would get. All my previous spark gap coil primaries never really got warm, but running 24KV @ ~50-100mA into the primary is a bit different than the much lower voltages and higher currents of a DRSSTC :) Phil suggested water cooling and I will probably go that route. Currently it does get fairly warm after a few minutes but I need a bigger variac before I can go much higher. Currently blowing the fuses at ~250Vbus...
slash128v6, Fri Aug 04 2017, 08:22PM
Nice! Yeah, I wasn't aware of how hot the primary would get. All my previous spark gap coil primaries never really got warm, but running 24KV @ ~50-100mA into the primary is a bit different than the much lower voltages and higher currents of a DRSSTC :) Phil suggested water cooling and I will probably go that route. Currently it does get fairly warm after a few minutes but I need a bigger variac before I can go much higher. Currently blowing the fuses at ~250Vbus...
Re: slash128 first DRSSTC build
slash128v6, Fri Aug 04 2017, 08:33PM
Oh and forgot about the rectifier question. Original that blew was a full bridge 75A 1200V module wired as two pairs in parallel. New module is an AEG PowerBlock:
slash128v6, Fri Aug 04 2017, 08:33PM
Oh and forgot about the rectifier question. Original that blew was a full bridge 75A 1200V module wired as two pairs in parallel. New module is an AEG PowerBlock:
Re: slash128 first DRSSTC build
slash128v6, Mon Aug 07 2017, 08:18PM
Currently throwing 50" sparks on 120VAC input... Getting a new 5KVA variac this week to take it up to 240VAC :)
slash128v6, Mon Aug 07 2017, 08:18PM
Currently throwing 50" sparks on 120VAC input... Getting a new 5KVA variac this week to take it up to 240VAC :)
Re: slash128 first DRSSTC build
Mads Barnkob, Tue Aug 08 2017, 06:55AM
No, I did not make any changes and the sound quality is not perfect, it properly needs some adaption to the coil its being used at. The interface is very simple and not really useful when operating a coil, its cheap and simple, I only used it for ease of operation while we tested.
Mads Barnkob, Tue Aug 08 2017, 06:55AM
slash128v6 wrote ...
Mads: question for you: in one of your videos it looks like you are using the OneTesla SD Interrupter. Did you make any changes to the firmware for your coil?
Mads: question for you: in one of your videos it looks like you are using the OneTesla SD Interrupter. Did you make any changes to the firmware for your coil?
No, I did not make any changes and the sound quality is not perfect, it properly needs some adaption to the coil its being used at. The interface is very simple and not really useful when operating a coil, its cheap and simple, I only used it for ease of operation while we tested.
Re: slash128 first DRSSTC build
slash128v6, Tue Aug 08 2017, 04:14PM
Thanks for the feedback. I apologize for my lack of knowledge here, but what functions would you consider useful and/or required in an interrupter? What are you using, something custom or ? Thanks!
slash128v6, Tue Aug 08 2017, 04:14PM
Thanks for the feedback. I apologize for my lack of knowledge here, but what functions would you consider useful and/or required in an interrupter? What are you using, something custom or ? Thanks!
Re: slash128 first DRSSTC build
futurist, Wed Aug 09 2017, 02:22PM
I use their older interrupter code, without lcd
I'm happy with it and only thing that is missing is the burst mode
Midi mode needs some minor details fixed to get better sound
Problem is in the way second note is handled. As far as I understand the code: if second note starts when first is playing, second pulse is added together and limited to max on-time set, which gives harsh "pop" sound
Example pink panther theme playing on my coil
Solution would be: if second note starts when first is playing, second pulse should start after dead time after first note stops. Counter that triggered second note should not be stopped
I'm not sure how to properly implement it in their code, and how long should dead time between pulses be
Hope someone could help
futurist, Wed Aug 09 2017, 02:22PM
I use their older interrupter code, without lcd
I'm happy with it and only thing that is missing is the burst mode
Midi mode needs some minor details fixed to get better sound
Problem is in the way second note is handled. As far as I understand the code: if second note starts when first is playing, second pulse is added together and limited to max on-time set, which gives harsh "pop" sound
Example pink panther theme playing on my coil
Solution would be: if second note starts when first is playing, second pulse should start after dead time after first note stops. Counter that triggered second note should not be stopped
I'm not sure how to properly implement it in their code, and how long should dead time between pulses be
Hope someone could help
Re: slash128 first DRSSTC build
slash128v6, Thu Aug 10 2017, 02:44AM
Appreciate the info! I'm going to play with increasing the on-time as well.
Got the bigger variac :)
Video:
slash128v6, Thu Aug 10 2017, 02:44AM
Appreciate the info! I'm going to play with increasing the on-time as well.
Got the bigger variac :)
Video:
Re: slash128 first DRSSTC build
slash128v6, Thu Aug 10 2017, 08:33PM
Over 6 feet now :)
slash128v6, Thu Aug 10 2017, 08:33PM
Over 6 feet now :)
Re: slash128 first DRSSTC build
slash128v6, Fri Aug 11 2017, 02:57AM
~80"
slash128v6, Fri Aug 11 2017, 02:57AM
~80"
Re: slash128 first DRSSTC build
slash128v6, Fri Sept 22 2017, 07:00PM
Question on primary cabling: I am running about 700-800A peak and using 4AWG welding cable for the primary connections. The cables get extremely hot, but not melting the insulation, yet. But I am concerned about the leg passing through the OCD and FB CTs melting the insulation on those CTs. I could rewind the CTs on larger cores and run larger gauge cable, but before I jump the gun I wanted to get an idea of what others are running for their primary cables.
I have upgrade the MMC and watercooled the primary, so both of those stay nice and cool
slash128v6, Fri Sept 22 2017, 07:00PM
Question on primary cabling: I am running about 700-800A peak and using 4AWG welding cable for the primary connections. The cables get extremely hot, but not melting the insulation, yet. But I am concerned about the leg passing through the OCD and FB CTs melting the insulation on those CTs. I could rewind the CTs on larger cores and run larger gauge cable, but before I jump the gun I wanted to get an idea of what others are running for their primary cables.
I have upgrade the MMC and watercooled the primary, so both of those stay nice and cool
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