WARNING!: Working with electricity is dangerous, all information found on my site is for educational purpose and I accept no responsibility for others actions using the information found on this site.
Read this document about safety! http://www.pupman.com/safety.htm
Introduction
This driver is among the simplest, with just six components it will be able of delivering high voltage with a strong enough current for various experiments.
There is also a push-pull version of this driver, more on that can be found following this link: http://wiki.4hv.org/index.php/Flyback_transformer
Considerations
The transistor used in this circuit should not have a voltage rating higher than 250V, this might in some cases cause problems.
At voltages higher than 12VDC input, the components will dissipate a lot of heat and the 2n3055 transistor is most likely to burn as it is weak.
MOSFETs are not suitable in this driver.
The frequency of operation in this circuit is determined by the capacitor across the transistors emitter and collector, experiment with the value of this capacitor to find the best performance, this capacitor have to be a good film or foil type (MKP/MKT)
Specifications
The driver is supplied with 12 to 17 VDC from a ATX psu.
Schematic
Construction
3rd may 2008
The driver is built on a piece of veroboard with multiply resistors to obtain the needed wattage rating, this is far from optimal as the load sharing between them is horrible.
The 2n3055 transistor is mounted on a 30 x 10 cm aluminium profile, this is just about enough to keep it alive doing long runs.
4th may 2008
I experimented with voltages between 12 to 17 VDC, there is no incredible performance with higher voltage compared to the amount of heating the higher voltage generates.
Different capacitors were tried, ranging from 10 nF to 300 nF, 220 nF was found to work the best for my flyback transformer.
8 primary windings and 4 feedback windings gave the best results.
Sparks
7th may 2008
18 to 20 mm sparks were achieved
Keeping the electrodes just far enough apart for no spark to jump, a beautiful corona breakout is visible.
With the output coupled through a home made salt water capacitor it was possible to have loud and very bright sparks.
Conclusion
This is the simplest way into working with high voltage, there is no dangerous supply voltages and at worst this will give you a shock or small burns.
It is cheap and simple, but inefficient and unstable.
As strange as it sounds this design is more flexible that it appears superficially. I worked with several transistors and found that a MJE13009 and similar along with much higher filter cap (50v 4000uf) ; higher wattage resistors will bring this to a workable level. not as efficient as the ZVS but not too poor either. The small TO-220 transistor must be efficiently heat-sinked – yet is does not appear to warm up at
5 amps and 18v. I pushed it higher for short periods and it survived and gave surprising performance.
The real problem with this design (aside from it basically being less efficient than the Mazzelli) is that the transistor should really never be a 3055 & the resistors should always be higher wattage than 2 and 5 watts.
(IMO) The Mazelli drivers that occasionally fail are generally due to people not using heat sinks or poorly made one as well.
What purpose does the small capacitor across the protection diode serve? I have mine set up with the diode but without the capacitor and it works fine.
Thanks.
Hi Alex
The diode and capacitors protects the transistor from high voltage transients that will eventually kill your transistor. The circuits works fine without, but it might die faster than if it had protection.
Kind regards
Mads
Thanks, I meant I have the diode in place and know it is to protect the transistor but what is the small capacitor for? isn’t the diode enough on its own to protect the transistor.
I have the diode but not the capacitor.
Thanks
Alex.
The capacitor will absorb most of the high voltage transients occuring doing switching of the load.
Thanks, just what I wanted to know ( :
Hello, I have made a similar driver to the one shown above but with MJ15003 transistor and a P600M diode, schematic from (By Dr Kilovolt) http://4hv.org/e107_plugins/forum/forum_viewtopic.php?37658
the 25V capacitor doesn’t seem to charge and therefore I get not HV OUT. i then tested the transistor with a different circuit, it worked fine….any help?
thanks v. much
PS. you can checkout the video of the circuit in action in first chat by Dr Kilvolt