Mini SSTC
Tom540, Mon Nov 26 2007, 07:34AMOkay, I started building this thing on Saturday just for the hell of it. I had an old secondary wound with 36 awg wire 2.5" x 10" so I decided to cut it in half and make a small coil out of half of it.
It's got a half bridge of IRF450's and a voltage doubler all crammed into a computer power supply case. Secondary is 4.5" long with a 4" sphere on top. It uses secondary base feedback and runs at 500KHz with the topload. The sphere is too big and I'm thinking of replacing it with a small toroid.
I did manage to kill the fets after taking the video. In the last two pics it was running off ~75v on the variac. The secondary gets warm after shorts runs.
Here's the pics:
Re: Mini SSTC
Mates, Mon Nov 26 2007, 08:36AM
Beautifull litle "dildo". It's a pity that the FET based bridge topology is so fragile (I destroyed my IRF450 half bridge immediatelly after turned it on)...
Mates, Mon Nov 26 2007, 08:36AM
Tom540 wrote ...
Okay, I started building this thing on Saturday just for the hell of it. I had an old secondary wound with 36 awg wire 2.5" x 10" so I decided to cut it in half and make a small coil out of half of it.
It's got a half bridge of IRF450's and a voltage doubler all crammed into a computer power supply case. Secondary is 4.5" long with a 4" sphere on top. It uses secondary base feedback and runs at 500KHz with the topload. The sphere is too big and I'm thinking of replacing it with a small toroid.
I did manage to kill the fets after taking the video. In the last two pics it was running off ~75v on the variac. The secondary gets warm after shorts runs.
Okay, I started building this thing on Saturday just for the hell of it. I had an old secondary wound with 36 awg wire 2.5" x 10" so I decided to cut it in half and make a small coil out of half of it.
It's got a half bridge of IRF450's and a voltage doubler all crammed into a computer power supply case. Secondary is 4.5" long with a 4" sphere on top. It uses secondary base feedback and runs at 500KHz with the topload. The sphere is too big and I'm thinking of replacing it with a small toroid.
I did manage to kill the fets after taking the video. In the last two pics it was running off ~75v on the variac. The secondary gets warm after shorts runs.
Beautifull litle "dildo". It's a pity that the FET based bridge topology is so fragile (I destroyed my IRF450 half bridge immediatelly after turned it on)...
Re: Mini SSTC
Marko, Mon Nov 26 2007, 10:07AM
I really don't have a clue how you guys get out at all with these tiny primaries. Have you tried calculating magnetizing current? What are dimensions of your primary coil?
I wouldn't want it to be >3 amps for IRFP450's and from glance I'd use like 15 turns or more.
Marko, Mon Nov 26 2007, 10:07AM
I really don't have a clue how you guys get out at all with these tiny primaries. Have you tried calculating magnetizing current? What are dimensions of your primary coil?
I wouldn't want it to be >3 amps for IRFP450's and from glance I'd use like 15 turns or more.
Re: Mini SSTC
Tom540, Mon Nov 26 2007, 03:21PM
I didn't calculate anything I just started slapping it together. I would have put more turns but thats all the wire I had in that size for the primary. I'll probably get some slightly thinner stuff and put more turns on it later after I replace the bad FETs.
I just ran out of the FGA40n60's I'm pretty sure they would be able to handle the 500KHz this thing runs at and they're much more heavy duty.
Tom540, Mon Nov 26 2007, 03:21PM
I didn't calculate anything I just started slapping it together. I would have put more turns but thats all the wire I had in that size for the primary. I'll probably get some slightly thinner stuff and put more turns on it later after I replace the bad FETs.
I just ran out of the FGA40n60's I'm pretty sure they would be able to handle the 500KHz this thing runs at and they're much more heavy duty.
Re: Mini SSTC
Tom540, Tue Nov 27 2007, 06:50AM
A small update. I made a tiny tape toroid. I'm not really happy with the spark length and it arcs to the primary past 90 volts on the variac.
Tom540, Tue Nov 27 2007, 06:50AM
A small update. I made a tiny tape toroid. I'm not really happy with the spark length and it arcs to the primary past 90 volts on the variac.
Re: Mini SSTC
Mates, Tue Nov 27 2007, 09:15AM
Put a protection plastic disk on your primary... you can use old LP - just cut a hole inside with some simple resistive wire based cutter (I've made one from old 30V 200W transformer, 20W 1ohm resitor in 5 minutes)
BTW: I like the sparks
Mates, Tue Nov 27 2007, 09:15AM
Tom540 wrote ...
A small update. I made a tiny tape toroid. I'm not really happy with the spark length and it arcs to the primary past 90 volts on the variac.
A small update. I made a tiny tape toroid. I'm not really happy with the spark length and it arcs to the primary past 90 volts on the variac.
Put a protection plastic disk on your primary... you can use old LP - just cut a hole inside with some simple resistive wire based cutter (I've made one from old 30V 200W transformer, 20W 1ohm resitor in 5 minutes)
BTW: I like the sparks
Re: Mini SSTC
Dr. Drone, Tue Nov 27 2007, 05:04PM
Dr. Drone, Tue Nov 27 2007, 05:04PM
Re: Mini SSTC
Tom540, Tue Nov 27 2007, 05:35PM
Your fets are 48 amp lol. I was thinking about getting some 44n50's off ebay for this but since I didn't blow them why bother?
Speaking of the fets. it turns out I didn't blow them. I blew the ultrafast diodes. I didn't replace them I just cut them off and it works fine.
I think a big fat copper primary might be overkill for my 4.5" secondary, hehe. I do have some 10 awg solid strand wire. I could just have that wind around without a former.
Tom540, Tue Nov 27 2007, 05:35PM
Christopher Miles wrote ...
I am down to 3.5 turns and have not blown a FET yet in 2 years. This coil must have 100 hrs on it. It now is at the local power company still running demo's.
Could go down to 2 turns but the FET's start to cry a bit @
Use a big fat copper primary.........................was a bitch to bend the copper however.
I am down to 3.5 turns and have not blown a FET yet in 2 years. This coil must have 100 hrs on it. It now is at the local power company still running demo's.
Could go down to 2 turns but the FET's start to cry a bit @
Use a big fat copper primary.........................was a bitch to bend the copper however.
Your fets are 48 amp lol. I was thinking about getting some 44n50's off ebay for this but since I didn't blow them why bother?
Speaking of the fets. it turns out I didn't blow them. I blew the ultrafast diodes. I didn't replace them I just cut them off and it works fine.
I think a big fat copper primary might be overkill for my 4.5" secondary, hehe. I do have some 10 awg solid strand wire. I could just have that wind around without a former.
Re: Mini SSTC
Bauerb2, Tue Nov 27 2007, 09:27PM
reminds me of my topload
that primary cable on mine is insanely thick, and was a pain to make. Is it alright if i use stranded copper cable instead of copper pipe/solid copper wire?
anyway, you're ahead of me, i have yet to run mine past 40V on the variac. It works great with all 9 turns and the mosfets only get slighty warm, while giving 2.5" discharge from a needle point. I also use sec base feedback instead of antenna, i think it runs smoother. Mine runs at 330kHz, using a fullbridge of IRFP460's which you can see on the bottom right. For the topload i used flexible black hose covered in Al tape.
I've used down to 2 primary turns on some of my earlier tests, only to see the current spike up, the mosfets heat up, and the streamer length go down a bit. your primary seems very close to the topload, which might be why it has arced there.
nice coil btw
-Andrew
Bauerb2, Tue Nov 27 2007, 09:27PM
reminds me of my topload
that primary cable on mine is insanely thick, and was a pain to make. Is it alright if i use stranded copper cable instead of copper pipe/solid copper wire?
anyway, you're ahead of me, i have yet to run mine past 40V on the variac. It works great with all 9 turns and the mosfets only get slighty warm, while giving 2.5" discharge from a needle point. I also use sec base feedback instead of antenna, i think it runs smoother. Mine runs at 330kHz, using a fullbridge of IRFP460's which you can see on the bottom right. For the topload i used flexible black hose covered in Al tape.
I've used down to 2 primary turns on some of my earlier tests, only to see the current spike up, the mosfets heat up, and the streamer length go down a bit. your primary seems very close to the topload, which might be why it has arced there.
nice coil btw
-Andrew
Re: Mini SSTC
Tom540, Tue Nov 27 2007, 11:47PM
Yeah I think that is probably overkill. My primary is made from CAT5
2 twisted pairs paralelled.
What size is your secondary?
Thanks, I was using 6 turns but the FETS seemed to get a little hot. I'm not too happy with the spark length considering I'm using a full wave doubler on this thing.
Tom540, Tue Nov 27 2007, 11:47PM
reminds me of my topload
that primary cable on mine is insanely thick, and was a pain to make. Is it alright if i use stranded copper cable instead of copper pipe/solid copper wire?
Yeah I think that is probably overkill. My primary is made from CAT5
2 twisted pairs paralelled.
anyway, you're ahead of me, i have yet to run mine past 40V on the variac. It works great with all 9 turns and the mosfets only get slighty warm, while giving 2.5" discharge from a needle point. I also use sec base feedback instead of antenna, i think it runs smoother. Mine runs at 330kHz, using a fullbridge of IRFP460's which you can see on the bottom right. For the topload i used flexible black hose covered in Al tape.
What size is your secondary?
I've used down to 2 primary turns on some of my earlier tests, only to see the current spike up, the mosfets heat up, and the streamer length go down a bit. your primary seems very close to the topload, which might be why it has arced there.
nice coil btw
Thanks, I was using 6 turns but the FETS seemed to get a little hot. I'm not too happy with the spark length considering I'm using a full wave doubler on this thing.
Re: Mini SSTC
Bauerb2, Wed Nov 28 2007, 03:38AM
My secondary is 4" in diameter and 8" tall 32awg wire ~1000 turns. That primary is 1/4" cable which i epoxied the hell out of to stay in that shape.
(poor plexi skills shown here)
there be the fullbridge and pirmary coil. i couldn't imagine using as much power as this primary can support. it's madness.
this coil is actually my graduation project for my senior year at high school, and im probably the only one putting effort into the project (other students do simple things like paint a wall in a room, or bake a cake
as their graduation projects). This should help me get into college and what not. My plans later are to audio mod it and increase power....MORE POWER!!!
This should be a fun project.
Bauerb2, Wed Nov 28 2007, 03:38AM
My secondary is 4" in diameter and 8" tall 32awg wire ~1000 turns. That primary is 1/4" cable which i epoxied the hell out of to stay in that shape.
(poor plexi skills shown here)
there be the fullbridge and pirmary coil. i couldn't imagine using as much power as this primary can support. it's madness.
this coil is actually my graduation project for my senior year at high school, and im probably the only one putting effort into the project (other students do simple things like paint a wall in a room, or bake a cake
as their graduation projects). This should help me get into college and what not. My plans later are to audio mod it and increase power....MORE POWER!!! This should be a fun project.
Re: Mini SSTC
Tom540, Wed Nov 28 2007, 05:11AM
Oh yeah thats a thick primary.
Tom540, Wed Nov 28 2007, 05:11AM
Oh yeah thats a thick primary.
Re: Mini SSTC
ragnar, Wed Nov 28 2007, 06:59AM
I'd like to ask, what model camera do you use to take your oh-so-crisp photos? (They really are good =P)
ragnar, Wed Nov 28 2007, 06:59AM
I'd like to ask, what model camera do you use to take your oh-so-crisp photos? (They really are good =P)
Bauerb2 wrote ...
(poor plexi skills shown here)
(poor plexi skills shown here)
Re: Mini SSTC
Bauerb2, Thu Nov 29 2007, 09:46PM
I used a Samsung Digimax D53. it's a cheap $89 camera my little bro got for christmas last year. it takes surprisingly good pictures. Since we are on the topic, what are good settings for taking coil streamers' pictures (ISO shutter speed, etc.)? i have had trouble getting good pictures of the actual sparks when it's on.
-Andrew
Bauerb2, Thu Nov 29 2007, 09:46PM
I used a Samsung Digimax D53. it's a cheap $89 camera my little bro got for christmas last year. it takes surprisingly good pictures. Since we are on the topic, what are good settings for taking coil streamers' pictures (ISO shutter speed, etc.)? i have had trouble getting good pictures of the actual sparks when it's on.
-Andrew
Re: Mini SSTC
Tom540, Thu Nov 29 2007, 10:34PM
Nikons take really really good macro shots. I can't seem to find my usb cable for my coolpix 4500 camera though.
Tom540, Thu Nov 29 2007, 10:34PM
Nikons take really really good macro shots. I can't seem to find my usb cable for my coolpix 4500 camera though.
Re: Mini SSTC
uzzors2k, Fri Nov 30 2007, 12:17PM
I thought I had replied here earlier, anyway nice and compact coil. The spark output looks good for just 90V, just solve the arc-over problem and run full power.
uzzors2k, Fri Nov 30 2007, 12:17PM
I thought I had replied here earlier, anyway nice and compact coil. The spark output looks good for just 90V, just solve the arc-over problem and run full power.
Re: Mini SSTC
Tom540, Fri Nov 30 2007, 05:08PM
Already did. just needs to be boxed up now. for some reason the sparks are sputtery in the video
videos here:
Tom540, Fri Nov 30 2007, 05:08PM
Already did. just needs to be boxed up now. for some reason the sparks are sputtery in the video
videos here:
Re: Mini SSTC
Bauerb2, Fri Nov 30 2007, 08:48PM
the sparks are so quick it happens when the camera shutter is 'closed' and it fades in and out. that sounds awesome btw, nicely done. What setup are you using to start the oscillation before the feedback circuit kicks on?
-Andrew
Bauerb2, Fri Nov 30 2007, 08:48PM
the sparks are so quick it happens when the camera shutter is 'closed' and it fades in and out. that sounds awesome btw, nicely done. What setup are you using to start the oscillation before the feedback circuit kicks on?
-Andrew
Re: Mini SSTC
Tom540, Sat Dec 01 2007, 07:13AM
The oscillation starts on its own. The interrupter takes care of all that.
I use this circuit with a half bridge of IRFP450's----> R2 and R1 values are diffrent. R2 is 47K and R1 is 1meg
]1196493129_487_FT34939_screamer_logic_rev_b.pdf[/ file]
Tom540, Sat Dec 01 2007, 07:13AM
Bauerb2 wrote ...
the sparks are so quick it happens when the camera shutter is 'closed' and it fades in and out. that sounds awesome btw, nicely done. What setup are you using to start the oscillation before the feedback circuit kicks on?
-Andrew
the sparks are so quick it happens when the camera shutter is 'closed' and it fades in and out. that sounds awesome btw, nicely done. What setup are you using to start the oscillation before the feedback circuit kicks on?
-Andrew
The oscillation starts on its own. The interrupter takes care of all that.
I use this circuit with a half bridge of IRFP450's----> R2 and R1 values are diffrent. R2 is 47K and R1 is 1meg
]1196493129_487_FT34939_screamer_logic_rev_b.pdf[/ file]
Re: Mini SSTC
Tom540, Wed Dec 26 2007, 05:50PM
Well I finished this over the holiday. Here is the youtube vid.
Tom540, Wed Dec 26 2007, 05:50PM
Well I finished this over the holiday. Here is the youtube vid.
Re: Mini SSTC
Bauerb2, Thu Dec 27 2007, 08:13AM
very nice results. i have also moved on with my own coil i mentioned above.
youtube vide here once i install an interupter things should get fun.
great results tom.
happy holidays.
Bauerb2, Thu Dec 27 2007, 08:13AM
very nice results. i have also moved on with my own coil i mentioned above.
youtube vide here
once i install an interupter things should get fun.great results tom.
happy holidays.
Re: Mini SSTC
Tom540, Thu Dec 27 2007, 03:02PM
Thanks,
Your sparks look good and they're really straight. You should get good length with an interrupter on there.
Tom540, Thu Dec 27 2007, 03:02PM
Thanks,
Your sparks look good and they're really straight. You should get good length with an interrupter on there.
Re: Mini SSTC
Zum Beispiel, Thu Dec 27 2007, 05:49PM
Just because you can't feel it doesn't mean it's not doing damage. Especially with a CW SSTC where there is a lot of power 
Zum Beispiel, Thu Dec 27 2007, 05:49PM
Bauerb2 wrote ...
youtube vide here
Looking good, but please, please, please use a chicken stick instead of your hand! youtube vide here
Just because you can't feel it doesn't mean it's not doing damage. Especially with a CW SSTC where there is a lot of power Re: Mini SSTC
Bauerb2, Thu Dec 27 2007, 09:51PM
yes, i know it's bad. i stated in the video description i did not want to do it, and i know it's not good for my body, but just for some kicks and giggles i did it anyway... only for a few seconds. i am perfectly aware of how much power is actually present.
at least i didn't do this
Bauerb2, Thu Dec 27 2007, 09:51PM
yes, i know it's bad. i stated in the video description i did not want to do it, and i know it's not good for my body, but just for some kicks and giggles i did it anyway... only for a few seconds. i am perfectly aware of how much power is actually present.
at least i didn't do this
Re: Mini SSTC
quicksilver, Sun Apr 06 2008, 04:02PM
I actually have a tough time watching things like that. Some people have a unique fascination with watching disaster-type things or accidents (this was NO accident obviously) but I had to turn that clip off. It's like watching someone ride a motorcycle foolishly: waiting for the spill to occur.
quicksilver, Sun Apr 06 2008, 04:02PM
I actually have a tough time watching things like that. Some people have a unique fascination with watching disaster-type things or accidents (this was NO accident obviously) but I had to turn that clip off. It's like watching someone ride a motorcycle foolishly: waiting for the spill to occur.
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