Hello, I am new to Tesla Coils and I am in process of designing one using a flyback transformer. I am curious whether I can have a duel resonance between the primary and secondary since the transformer is already wound and I have no control over the inductance. Also is it possible for it to look like the 'classical' tesla coil with a slender middle that goes to a toroid top load? Most of the designs that I have seen using a flyback only have small arcs from a pointed electrode.
Re: Flyback Transformer
Posted by Bert Hickman on 12/30/2009, 6:08 pm, in reply to "Flyback Transformer " Message modified by board administrator 12/30/2009, 6:58 pm
--Previous Message-- : Hello, I am new to Tesla Coils and I am in process of designing one using a : flyback transformer. I am curious whether I can have a duel resonance : between the primary and secondary since the transformer is already wound : and I have no control over the inductance. Also is it possible for it to : look like the 'classical' tesla coil with a slender middle that goes to a : toroid top load? Most of the designs that I have seen using a flyback only : have small arcs from a pointed electrode. :
Hi Josh,
The complex geometry of the secondary winding is not optimum for getting the sharply defined resonant frequency that's desirable for a Tesla Coil. Various sections of the secondary "Pi" winding will combine with various parasitic turn-to-turn capacitances to create various combinations of LC circuits inside the winding. So, instead of getting a single (and optimal) resonant frequency, you'll get a variety of suboptimal resonant frequencies. These separate resonant frequencies only excite subsections of the winding, but not the entire winding (as in a Tesla Coil).
Although you can tune the primary so that it is tuned to one of these suboptimal frequencies, the output will be disappointing when compared to a classic Tesla Coil. You also risk internal arcing as some sections of the winding can become overstressed. Once the winding insulation system fails, the winding is destroyed and must be rewound or the transformer replaced. Flybacks are good for low to moderate output power applications. There are many circuits on the Internet that will drive flybacks to deliver tens or even hundreds of watts of output power. You may wish to search the forum section on the 4hv site: <a href="https://www.4hv.org">http://www.4hv.org</a>
If you search for "flyback driver" on the 4hv site, you can also read numerous discussions about flyback transformers, driver circuits, and results obtained from a variety of experimenters. You may also wish to read the HV Wiki to read about Flyback Transformers:
My goal is to have a SSTC to act as a plasma speaker. Based on your reply and additional research into the flyback design, I found that it will give me a better audio sample and the design is somewhat easier than the air-core transformer design but I feel as though I am cheating myself and I am not getting the full Tesla Coil design experience. I am in the process of switching my design to using an air-core transformer using a sphere top load. What supply voltage do I need in order to operate the coil? I have seen many sites that use a 12Vdc supply to power their SSTCs while others use high voltage transformers (NST in particular). I am looking to produce sparks of 30cm and I feel that using a 12Vdc supply will not give me enough power to achieve this.
--Previous Message-- : --Previous Message-- : Hello, I am new to Tesla Coils and I am in process of designing one using : a : flyback transformer. I am curious whether I can have a duel resonance : between the primary and secondary since the transformer is already wound : and I have no control over the inductance. Also is it possible for it to : look like the 'classical' tesla coil with a slender middle that goes to a : toroid top load? Most of the designs that I have seen using a flyback only : have small arcs from a pointed electrode. : : : Hi Josh, : : The complex geometry of the secondary winding is not optimum for getting : the sharply defined resonant frequency that's desirable for a Tesla Coil. : Various sections of the secondary "Pi" winding will combine with : various parasitic turn-to-turn capacitances to create various combinations : of LC circuits inside the winding. So, instead of getting a single (and : optimal) resonant frequency, you'll get a variety of suboptimal resonant : frequencies. These separate resonant frequencies only excite subsections : of the winding, but not the entire winding (as in a Tesla Coil). : : Although you can tune the primary so that it is tuned to one of these : suboptimal frequencies, the output will be disappointing when compared to : a classic Tesla Coil. You also risk internal arcing as some sections of : the winding can become overstressed. Once the winding insulation system : fails, the winding is destroyed and must be rewound or the transformer : replaced. Flybacks are good for low to moderate output power applications. : There are many circuits on the Internet that will drive flybacks to : deliver tens or even hundreds of watts of output power. You may wish to : search the forum section on the 4hv site: <a : href="https://www.4hv.org">http://www.4hv.org</a> : : If you search for "flyback driver" on the 4hv site, you can also : read numerous discussions about flyback transformers, driver circuits, and : results obtained from a variety of experimenters. You may also wish to : read the HV Wiki to read about Flyback Transformers: : : <a : href="http://wiki.4hv.org/index.php/Flyback">http://wiki.4hv.org/index.php/Flyback</a> : : Good luck and best wishes, : : Bert :
--Previous Message-- : Hey Bert, : : My goal is to have a SSTC to act as a plasma speaker. Based on your reply : and additional research into the flyback design, I found that it will give : me a better audio sample and the design is somewhat easier than the : air-core transformer design but I feel as though I am cheating myself and : I am not getting the full Tesla Coil design experience. I am in the : process of switching my design to using an air-core transformer using a : sphere top load. What supply voltage do I need in order to operate the : coil? I have seen many sites that use a 12Vdc supply to power their SSTCs : while others use high voltage transformers (NST in particular). I am : looking to produce sparks of 30cm and I feel that using a 12Vdc supply : will not give me enough power to achieve this. :
Hi Josh,
Most solid state coils operate from relatively low DC supply voltages - from tens to to hundreds of volts. A few special systems use costly high voltage power transistors (such as Greg Leyh's new solid state coils). These may operate with DC supply voltages as high as 1-3 kV.
All Tesla Coils using NST's either use spark gap switching or a newer solid state "equivalent" using a stack of Sidac IGBT Spark Gap (SISG) solid state switching modules. (Look up SISG in the Pupman archives at www.pupman.com for more information). NST-powered coils are not easily modulated for audio.
Tesla Coil spark length is a function of design/construction efficiency and input power. A well-designed Tesla Coil can easily deliver at least 30 cm (~12" sparks with an input power of 90 watts. The input power could be supplied by a 12V power supply capable of supplying 7.5A, or a 90 volt supply delivering 1A... either will work as long as the SSTC circuit is designed to work at the desired voltage.
If your focus is to make a coil that you can use to drive a relatively high fidelity plasma "speaker", and if you don't have much prior electronics design experience, you may want to check out the Plasmasonic Tesla Coils and kits from Dan McCauley at Eastern Voltage Research. The best audio fidelity tends to occur with coils operating at high frequency (1 MHz+) and short output sparks (actually more like an almost silent flame-like corona) that's only 1/2" - 2" long. This severely limits low frequency performance. Systems that generate longer sparks often use DRSSTC's or higher power SSTC's. While you can get much louder sound from these larger systems, they tend to have poorer audio fidelity due to spark-generated artifacts (hissing, crackling). Also, audio modulated DRSSTC's are limited to hundreds of Hz to a few kHz by the nature of their operation. For some ideas for both types of systems, see Dan's site:
--Previous Message-- : --Previous Message-- : Hey Bert, : : My goal is to have a SSTC to act as a plasma speaker. Based on your reply : and additional research into the flyback design, I found that it will give : me a better audio sample and the design is somewhat easier than the : air-core transformer design but I feel as though I am cheating myself and : I am not getting the full Tesla Coil design experience. I am in the : process of switching my design to using an air-core transformer using a : sphere top load. What supply voltage do I need in order to operate the : coil? I have seen many sites that use a 12Vdc supply to power their SSTCs : while others use high voltage transformers (NST in particular). I am : looking to produce sparks of 30cm and I feel that using a 12Vdc supply : will not give me enough power to achieve this. : : : Hi Josh, : : Most solid state coils operate from relatively low DC supply voltages - : from tens to to hundreds of volts. A few special systems use costly high : voltage power transistors (such as Greg Leyh's new solid state coils). : These may operate with DC supply voltages as high as 1-3 kV. : : All Tesla Coils using NST's either use spark gap switching or a newer : solid state "equivalent" using a stack of Sidac IGBT Spark Gap : (SISG) solid state switching modules. (Look up SISG in the Pupman archives : at www.pupman.com for more information). NST-powered coils are not easily : modulated for audio. : : Tesla Coil spark length is a function of design/construction efficiency : and input power. A well-designed Tesla Coil can easily deliver at least 30 : cm (~12" sparks with an input power of 90 watts. The input power : could be supplied by a 12V power supply capable of supplying 7.5A, or a 90 : volt supply delivering 1A... either will work as long as the SSTC circuit : is designed to work at the desired voltage. : : If your focus is to make a coil that you can use to drive a relatively : high fidelity plasma "speaker", and if you don't have much prior : electronics design experience, you may want to check out the Plasmasonic : Tesla Coils and kits from Dan McCauley at Eastern Voltage Research. The : best audio fidelity tends to occur with coils operating at high frequency : (1 MHz+) and short output sparks (actually more like an almost silent : flame-like corona) that's only 1/2" - 2" long. This severely : limits low frequency performance. Systems that generate longer sparks : often use DRSSTC's or higher power SSTC's. While you can get much louder : sound from these larger systems, they tend to have poorer audio fidelity : due to spark-generated artifacts (hissing, crackling). Also, audio : modulated DRSSTC's are limited to hundreds of Hz to a few kHz by the : nature of their operation. : For some ideas for both types of systems, see Dan's site: : : http://www.easternvoltageresearch.com/index.htm : : Good luck, : : Bert :
Hey Bert,
I have started designing the transformer for my Tesla coil, and I just wanted to run some things by you before I start construction. I am going for a DRSSTC, so I started designing my secondary in which I found the resonant frequency and then I tuned the primary accordingly.
Secondary
Diameter of secondary - 5inches # of turns - 950 wire diameter - 0.0126inches (28AWG) L(Using the inductance formula for a Helical Coil) = 21.382mH self capacitance of coil - 9.47pF
Capacitance of topload (sphere) - 27.8pF Resonant Frequency - 178.285kHz
L(using the inductance formula for Flat Spiral Coil) - 9.92uH C(based on resonant frequency and inductance of primary) - 80nF
*The schematic of the XFMR is shown here [img][/img]
I have the following gain vs freq and impedance vs freq plots shown below [img][/img]
I am having problems simulating what the output voltage and current as well as the input current. I have looked around the web for some way to calculate these values but cannot find a clear cut way.
Also, I am going to have two sets of switching MOSFETS connected in a half bridge configuration at the input to the primary but I am wondering at which voltage should I be pulsing at?