| SINGLE TUBE DRIVER FOR FLYBACKS (WITH PL500 TUBE) |
| Starting from a thread from .HV.org forum (thanx Philcogrump) I was inspired to realise myself a tube driver for my hobbyst play with plasma globes. I built a little setup using my old double PL500 VTTC as a starting point, with only one tube, fed from mains, in CW mode (full AC wave rectifyed). It works very well, with beautiful hot streamers inside the light bulbs. The sparks in free air are not too long (max 1 cm-- maibe more with higher voltages input, I used only 220 vac), but with yellow hot arcs. Anyway the principal advantage is the possibility of long runs without the necessity of massive heatsinks and kickback risks of solid state drivers. Working in CW mode, the driver put a lot of power in the flyback. |
| STREAMERS IN LIGHT BULBS (I used a 300 W light lamp) |
| The weak points of my setup - the input voltage is only 220 vac full wave rectifyed. I suppose that the spark output from the flyback would be longer for higher voltages input (600-700 VDC). In the old tube TVs the flyback run at 400-600 poulsed DC input (300 V rectifyed mains + 300 V from the recuperation cap). - the nominal fillament voltage of the PL500 is 27 V at 0.3 A. My fillament transformer give 27.3 V, but it drops at 24.9 V under load, this is bad. The xfrm is encapsulated, so I couldn't add some more extraturns. - the connections are too long, this is bad. - the primary cap is not addapted for resonance (I just used some caps I had around). |
|
 |
 |
| For pics I used a digital camera. |
| NEXT STEP I doubled the input voltage (220 v / 220 v @ 300 watts transformer in serie with my variac). The results are great: streamers in the light bulbs without touching the glass wall, bigger arcs. The schema is almost identical with the exception of Rg2 which was upgraded at 4.1 kohms @ 5 watts. |
| PICTURES |