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Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
dex wrote ...
Okay,how to construct a table top SGTC which doesn't give streamer jolts ? Except reducing top load size to minimum I don't know of any guidelines.Can I hear any tips from experienced coilers?Some small SGTCs (streamer lenght 5"-10") do bite while others simply don't.
Its a question of the current in a ringup, if you look closer at the different topologies it will make sense.
SGTC and DRSSTC dumps a capacitors energy into the primary circuit with short and high peak values whereas VTTC and SSTC works with a much lower peak currents for longer times.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Hey guys
This has been discussed several times before, the story in it's simplest goes as follows:
Humans can't feel the HF AC component of Tesla coil current, even up to amps in CW which I've tested on myself. What makes DRSSTC's and SGTC's hurt is the high current DC component which flows from the topload charged at high voltage, producing a shock not unlike a VDG would do. From this one could conclude that coils which have large toploads and produce high peak voltages - like SGTC's or DRSSTC's - will tend to produce significant shocks, while coils that have little or no topload and produce lower output voltages - such as CW, QCW or VTTC's - will tend to produce little shock.
If you want to make a less shocking SGTC, make one without topload!
Registered Member #2292
Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795
My experience with pain and Tesla coils has been some what different. From what I have found BPS plays a very large role in the pain.
I noticed this with my QCW, when running large say 4 foot sparks I can get hit with this and only feel a small pinch, I assumed this was in part from the sudden rise in temp at that point. However if you take the same QCW and bring the BPS up to sat 30Hz and make the sparks much smaller (maybe only a couple inches long) they suddenly start to hurt like S!@#
With this case the peak energy is lower with the more painful sparks, but the pain is much higher.
I'm not drawing any conclusions here. Just my observation.
Registered Member #4074
Joined: Mon Aug 29 2011, 06:58AM
Location: Australia
Posts: 335
Marko wrote ...
Hey guys
This has been discussed several times before, the story in it's simplest goes as follows:
Humans can't feel the HF AC component of Tesla coil current, even up to amps in CW which I've tested on myself. What makes DRSSTC's and SGTC's hurt is the high current DC component which flows from the topload charged at high voltage, producing a shock not unlike a VDG would do. From this one could conclude that coils which have large toploads and produce high peak voltages - like SGTC's or DRSSTC's - will tend to produce significant shocks, while coils that have little or no topload and produce lower output voltages - such as CW, QCW or VTTC's - will tend to produce little shock.
If you want to make a less shocking SGTC, make one without topload!
Marko
I can vouch for this theory. I have been running my small SGTC at roughly 200VA both with and without a topload. Without a topload (and after fiddling with the tuning) I managed to get 60mm+ streamers, which sent a minor "pins and needles" sensation through your hand, but was not incredibly painful.
With the addition of a 120mm smooth stainless ball (and some re-tuning, obviously) I managed to get roughly 280mm streamers to the air. These streamers were obscenely painful to interact with, to the point of involuntarily dropping the metal stick I was using to conduct them. The most painful moment was definitely when the streamer first makes contact, dumping the topload's charge to ground.
Registered Member #2566
Joined: Wed Dec 23 2009, 05:52PM
Location:
Posts: 147
Goodchild wrote ...
My experience with pain and Tesla coils has been some what different. From what I have found BPS plays a very large role in the pain.
I noticed this with my QCW, when running large say 4 foot sparks I can get hit with this and only feel a small pinch, I assumed this was in part from the sudden rise in temp at that point. However if you take the same QCW and bring the BPS up to sat 30Hz and make the sparks much smaller (maybe only a couple inches long) they suddenly start to hurt like S!@#
With this case the peak energy is lower with the more painful sparks, but the pain is much higher.
I'm not drawing any conclusions here. Just my observation.
Interesting observation! Do you think that currents of the received discharges had different waveshapes in the the second case? I just remembered reading about someone's experience with SGTC and break rates. With small BPS and shorter sparks there were unpleasant shocks felt , but with high BPS and longer sparks shocks were less upleasant (despite higher power level input).
XravenorX wrote ...
I can vouch for this theory. I have been running my small SGTC at roughly 200VA both with and without a topload. Without a topload (and after fiddling with the tuning) I managed to get 60mm+ streamers, which sent a minor "pins and needles" sensation through your hand, but was not incredibly painful.
With the addition of a 120mm smooth stainless ball (and some re-tuning, obviously) I managed to get roughly 280mm streamers to the air.
Amazing increase of streamer lenght when you added topload. Are you sure the power inputs were the same in both cases and resonances established?
Registered Member #4074
Joined: Mon Aug 29 2011, 06:58AM
Location: Australia
Posts: 335
I don't think I achieved resonance without the topload, I simply tuned the primary for a higher frequency (got to the last tap), without changing the MMC or coil and roughly 6cm was the best I could get. I wasn't really trying to achieve anything, just testing it's performance without the topload. Interestingly, I placed a circular valve handle onto the secondary which I use to hold the stainless sphere in place and when powered up (still putting out only 60mm streamers) the increased metallic surface area would give more distinct shocks than just the wire from the secondary.
I used the same ballasting in both cases, however I don't think the power transferred to the output would be the same.
This has reminded me to make a new video of the coil running with it's shiny new sphere. The streamers to the air are very fluid-like, occasionally you see little streamer "tornado's" off the top of the sphere.
Registered Member #7267
Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407
I zapped myself once on accident with my mini sstc. I was testing the strength and size of the E field at lowest power input. I turned the power on my variac up to about 25 or 30ish VAC (if i remember correctly) until there was just the smallest amount of visible corona on the breakout point, probably half inch spark or less. I held a large 48" black light tube and started to walk toward the coil until the tube lit up and the closer i got the brighter it got etc... And not thinking responsibly I got my hand too close to the toroid, maybe inch or two away, and a small spark jumped off the toroid and hit my hand. OUCH! Thats the only time I've ever been zapped from a tesla coil so I dont know how it would compare to increased power input, and i dont remember exactly but the little sstc was interrupted at something like a 50-70ish % duty cycle, but WOW even at 30ish VAC input it was very very uncomfortable. It hit me right in my pinky finger and I felt it all the way to my neck. I think I was more startled by it by anything. Also glad i somehow didnt drop the blacklight or squeeze so hard and shatter it in my hand.. Within 30 mintutes of being zapped I had a little nosebleed which really worried me! I have no idea if it was related to being zapped or just because it was cold and dry, or bit of both probably. That experience inspired me to do some googling on what can happen if you touch the spark and any long term side effects and so on.. What i came across is just as mentioned by a few people already, that our nerve receptors respond only slightly or not at all to the high frequencies of a TC, which makes the feeling of being zapped only slightly painful, and that most of the time people are more startled and shocked by what happened so fast that they tend to think it was very painful when in fact the pain was very minor but more of an uncomfortable feeling, and in some cases no pain at all. Well I dont know about anyone else but I sure as heck felt some pain! And because our nerve receptors dont always respond, doesnt mean that we dont suffer any nerve damage. Some long-time coilers who have been zapped many times also show signs of nerve damage later in life such as severe shaky hands from being struck there many times. I never came across anything related to nosebleeds, and unfortunately no reports of becoming a mind reader, growing extra limbs, or being able to contact E.T. All the information out there goes without saying, be careful, be responsible, wear protective gear whenever possible, and never under estimate the power of electricity, and the power of nature.. especially when we play with it for our own amusement.
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Touch the QCW or VTTC sparks
and I felt it all the way to my neck. I think I was more startled by it by anything. Also glad i somehow didnt drop the blacklight or squeeze so hard and shatter it in my hand.. Within 30 mintutes of being zapped I had a little nosebleed which really worried me! I have no idea if it was related to being zapped or just because it was cold and dry, or bit of both probably. That experience inspired me to do some googling on what can happen if you touch the spark and any long term side effects and so on.. What i came across is just as mentioned by a few people already, that our nerve receptors respond only slightly or not at all to the high frequencies of a TC, which makes the feeling of being zapped only slightly painful, and that most of the time people are more startled and shocked by what happened so fast that they tend to think it was very painful when in fact the pain was very minor but more of an uncomfortable feeling, and in some cases no pain at all. Well I dont know about anyone else but I sure as heck felt some pain! And because our nerve receptors dont always respond, doesnt mean that we dont suffer any nerve damage. Some long-time coilers who have been zapped many times also show signs of nerve damage later in life such as severe shaky hands from being struck there many times. I never came across anything related to nosebleeds, and unfortunately no reports of becoming a mind reader, growing extra limbs, or being able to contact E.T. 
All the information out there goes without saying, be careful, be responsible, wear protective gear whenever possible, and never under estimate the power of electricity, and the power of nature.. especially when we play with it for our own amusement.