Miniature Vacuum Tube Tesla Coil
I discovered I could make a very simple source of very
strong RF energy at around 30MHz that is capable of lighting neon bulbs and
fluorescent tubes, all from a short distance. The really cool thing about it, is
that it uses subminiature "pencil" tubes, and a camera flash for the
B+ supply. You don't need many turns on the secondary, just a few to step the
voltage up slightly and provide proper feedback to the grid.
You can start out by winding your secondary coil, I used 24AWG wire for my secondary, and a "D" battery as the coil form. Wind about 30 or more turns in a nice smooth row with no overlapping turns. After you have it all wound up on the battery, put a layer of electrical tape over the whole thing to hold it together, then CAREFULLY slip it off of the battery. You may want to reinforce it further by winding more tape on the outside of it, but its your choice.
Click on images to enlarge
Click here for the schematic
You will need:
Now hook up your filament supply, and allow it to warm up. Once the filament is hot, disconnect the wire from the camera flash going to B+ and charge the camera flash. Now, you should have a neon bulb on the output, just connect one of it's wires to the output. Take the wire from the camera flash, and quickly press it onto the B+ input, the neon bulb should strike, if it does, congratulations you have just made a Mini VTTC.
Watch for heating of the tube, if you run it long,
the tube will heat up, which is not a good thing.
**May be needed if Grid #2 starts to heat up.
***Will draw more power with better performance, you
will need a more powerful B+ supply.
I will sell 5784WB pentodes for 9$ each, email me at electrontube @ sbcglobal.net