Wednesday, October 22, 2014

The Quad Flyback Driver --200KV from color TV flybacks!

Ok, Here it is, I will post still pics later.  This is a 200kv DC generator that uses 4 color TV flyback transformers in series.  There are NO voltage multiplication circuits here.  It is powered by my homemade CD-707 lab supply using a 1200W mosfet, IFXB100N50.   It uses a lot of power and I am pushing the limits of flyback design here.  I used to think 2 flybacks were a problem!  Four of them was more then a challenge. Put in oil, and with enough insulation and testing, this circuit runs incredibly well.  It is important that the driver can be tuned, and all primary windings are done in the same direction.  Also, very large wire must be used--HV TV wire--even in oil, 200kv will arc through almost anything.  I burned out a lot of wire before I found one that can handle it.  It runs on about 22volts at 7.8amps (about 170W).  Care must be taken not to overdrive the flybacks. A long in-oil capacitor bank prevents punching too much power through the integral flyback diodes and helps collect peak voltages.   The voltage can arc over 7 inches!  It might be possible to do more, but after a certain point the voltage on one side will probably blow through the flyback's insulation even in oil.  So using more flybacks in this way may not work long, even in oil.  To my knowledge I am the first person/lab to ever put 4 flybacks directly in series secondary connection on YouTube.

The diodes on each end must be protected since the newer color TV flybacks typically have 4 fast HV diodes in them, some more some less.  They are arranged between separated windings to prevent arcing inside the flyback itself.  Not just one diode as is often assumed. The early TV sets only had one thermionic diode tube for CRT HV system. Since the use of solid state diodes, most flybacks have at least 4 and as many as 8 or more in them.  However, on the ground and hot sides, the last diodes have to handle a lot of power when in a chain like this.  Keeping this circuit from overloading or damaging those diodes is possible but you don't want to overdrive them with too much current. Flyback failure can happen very quickly and without warning.  Once a flyback fails--there is no fixing it.  This can be from internal arcing, melted windings or diode failure.  Under some conditions a DC flyback can even change to AC--usually if it's over powered without a load.  This is rare however, I have only seen it happen once.  Many people want to remove the diodes to get an AC output, this is practically impossible since these modern DC flybacks are made of very tough materials and cannot simply be melted away or cut apart. Even very strong acids are ineffective.  Best if you want an AC flyback, buy one or wind one yourself.  There is a video on my YouTube channel "mostlymacros" describing this.  I wound up to 20kv high current AC flybacks myself. There are some companies still making them as well for various devices and they are easy to order last I checked.. Also a good resonant frequency must be found to get peak voltages out of this kind of system.  This can be done with a PWM, a 555 timer will also work fine. I have many more pics will post later (a lot of disks to burn!).   I also have other projects not yet posted, including an ion drive working model. Be sure to see my latest project below, the VTTC1000.

A Power Beam Tube Tesla coil---First look

 I know it's been a long time since I've posted anything.  That does not mean I have not been doing anything!  This time, after my successful YouTube post of the 200kv Quad Flyback driver powered by my CD-707 (Not yet posted here but can be seen on my YouTube "mostlymacros" channel), I designed a Tesla coil around a large power beam tube.  The top tip is a crossbow bolt on a coffee can as my capacitor.  Features of my oscillator design include a stabilization coil, plate tune and (~I/E) control.

 I kept the plate voltage, provided by a high current/voltage supply I built--to about 1000 volts for these tests as I did not want to damage the camera I was using.  The coil can create sprites as high as about 5 inches or more.  Making it capable of over 120,000 volts with full arc load across secondary.
Tesla coils produce very powerful EM fields.  This one operates at about 300khz (300kc) and operates as high as 1500 volts at about 1amp.  I have yet to get a complete reading however since I must build a meter capable of handling the RF produced as well as the high voltages used.  Newer digital meters have pathetically low voltage levels.  I have only one cat. III meter/scope as can be seen in the YouTube Video--and it's too expensive to risk here!

 Here is my video of the project, click here to view.  Coil is not at full power yet and not complete, I will create another video when it is and upload. 
I hand wound this coil entirely myself, as well as designed the circuits that drive it. You will not find the schematic for this online until I put it up there.  However, there are quite a few VTTC/SSTC schematics online, almost none of which I have tested as I often do my own schematics.  I designed it around a large power beam tube that was probably used for the bigger color TV sets back in the 1960s-70s.   I also came up with an idea for isolation of primary from secondary issues using a large plastic beaker.  Consequentially--I am able to run the coil with far more power and even replace or swap out the HV secondary!  Really useful for testing.  My schematic for this circuit is available on request (email me if interested). I only have a hand drawn version for now in my notebook. I will eventually draw it on CAD software, as I have done other projects on here.  Be sure and watch the YouTube video.  I know it turned out unexpectedly dark--sorry about that--next time I need to use the better camera!  It looked great on my camera in playback. I usually use a relatively inexpensive camera for most of these videos/pics since I don't want to fry my high end one.

I don't like to get my good cameras too close to projects like this!  Any kind of Tesla coil produces very powerful EM/RF fields and can produce several 1000 volts in devices near by so watch things like remote controls, cameras, laptops and memory cards. A metallic and thus somewhat shielded cameras is best. It is not complete yet, When I get the diodes for it's power supply (coming in the mail)-- it will be a self-powered unit that plugs right into any wall outlet.  It can run on 120volts but requires a lot of power, as much as 6 amps in high settings on the 120volt side of things.  About half what a regular microwave oven needs or so.  Since it is an oscillator working with the feedback principle it produces a large amount of tuned RF at about 300khz, so you don't want to hook any long wires to VTTC/SSTC projects as they may create serious radio interference on nav. beakons and or other radio devices.  Some filtration of the AC 120 volt side and/or HV AC side can help keep this RFI to a minimum.  Thanks for checking out my site--Please subscribe if interested--I have been busy and will try to post more often.  I have a backlog of cards to upload, about a half dozen videos and 100s of pics.  So keep comming back!  Thanks--G.Beasley KF7DFP