phenol
0
- Joined
- Oct 30, 2007
- Messages
- 533
- Points
- 18
So i got this 60W tube, a 1200mm long bong. It's too long to take a complete shot of it without gluing the camera on the ceiling, so i took 2 shots instead. It needs 22mA of current to produce 60W. Pic 1 shows the business end of the tube, a multimeter registering the tube current (slightly <5mA here), the faint discharge in the bore and a pathetic approximation of a cooling system. It works fine for short (1min or so) bursts at 5-6mA.
Pic2 shows the anode end and a 'power supply'. The ball of wires and components is a pwm push-pull driver with 2 very good mosfets (they run fine at 5-6A @ 25V w/o any reasonable heatsinking) torturing a small TV flyback transformer with rewound bifilar primary. The HF HV AC from it goes to a TV CRT cascade (voltage multiplier). The output of the cascade, the heavy grey wire, goes to the anote of the co2 tube thru a ballast resistor.
Those flybacks and cascades are only designed to deliver a couple of milliamps. Im really pushing it beyond its limits, but i'll continue doing so until i get a real power supply from china or until it ruptures. I will try putting two cascades in parallel for fun.
As it is now, i can only draw 5.5-6mA max, nowhere near 22mA for 60W.
Even with just 5mA in the tube, it was able to produce a white hot spot on a piece of floor tile /pic 3/. The actual spot is smaller than it appears. From the burn marks on wood, it seems like TEM00 at this power.
Something happened that brought my dormant safety instinct back to life...while i was melting a piece of glass some 60cm from the exit aperture, i saw that the water hose on the OC is smoking. While the glass IS opaque to deep IR, it appears that, when molten, and maybe not only then, it creates specular reflections powerful enough to burn stuff. There is a clear burn mark on the hose.
i'll post more burning pictures once i find a way to pump more current into the tube.
Pic2 shows the anode end and a 'power supply'. The ball of wires and components is a pwm push-pull driver with 2 very good mosfets (they run fine at 5-6A @ 25V w/o any reasonable heatsinking) torturing a small TV flyback transformer with rewound bifilar primary. The HF HV AC from it goes to a TV CRT cascade (voltage multiplier). The output of the cascade, the heavy grey wire, goes to the anote of the co2 tube thru a ballast resistor.
Those flybacks and cascades are only designed to deliver a couple of milliamps. Im really pushing it beyond its limits, but i'll continue doing so until i get a real power supply from china or until it ruptures. I will try putting two cascades in parallel for fun.
As it is now, i can only draw 5.5-6mA max, nowhere near 22mA for 60W.
Even with just 5mA in the tube, it was able to produce a white hot spot on a piece of floor tile /pic 3/. The actual spot is smaller than it appears. From the burn marks on wood, it seems like TEM00 at this power.
Something happened that brought my dormant safety instinct back to life...while i was melting a piece of glass some 60cm from the exit aperture, i saw that the water hose on the OC is smoking. While the glass IS opaque to deep IR, it appears that, when molten, and maybe not only then, it creates specular reflections powerful enough to burn stuff. There is a clear burn mark on the hose.
i'll post more burning pictures once i find a way to pump more current into the tube.