Science/Engineering/Technical forums

Hi Chrismb
neither nor, at least for beginning, I don't want to extract any power, just being happy if the device turns with high speed without suppling pressed air.
There are a lot of videos about diy turbo charger turbines on Youtube, but they all use very large combustion chambers. I should like ...

Hi,
after building a very small but working pulse jet
http://www.youtube.com/watch?v=FX6hDPiWGDg
I want to try a gasturbine with a car turbo charger, but I don't have much experience with this kind of machines. Has anyone here advices what mistakes can be made. I want to make the machine as small ...

Hi,
I'm afraid the limiting resolution comes from the construction of the tube. The source is not the cathode but the crossover of the electronbeam just in front of the negativ biased wehnelt grid. The single lense is half the way between the crossover and the sample, so the demagnifiaction can't ...

Hi,
some more images from the vidicon-microscope.
A picture of a tick which was unlucky to cross our garden table and a operational amplfier. The first one is colored with 'Photo Shop' for nicer viewing
and the second allows to estimate the resolution which is arround 10 µm.
Thomas

Sorry, in my last post I set the wrong links
Field emission microscope
Field ion microscope

Hi,
I used ballongas because of it light weight. Because the vidicon is mounted vertical, I supose the helium readly fills the tube, preventing the air from reached the uppermost cathode. Other clean and cheap gases like nitrogen or argon are to heavy. People from Linde corporation ( the biggest ...

Hi John,
my experiment is nice for demonstration but I'm not shure if its good enough for professional work. The resolution will be mostly 10 µm, not to compare with the real worlds SEMs having arround 2 to 10 nm.
Another drawback is the vidicons cathode made from sensible barium layers which are ...

Hi Doug
You're right. For looking the cathode You have to change the voltages. For example for the DG 7-74 ( 3 ARP 1)
Uf 6,3 V > 2 V
Ug1 ~ -50 V > 0V
Ua1 500 V > 1500V
Ua2 1000 V > 1500V
Ug3 ~100V > 0V
Because there is no negative bias at the wehnelt g1 You have to reduce the heater voltage to ...

Hi,
I made some experiments with old crt, picture- and vidicontubes. With the crt or picture tubes you can make magnified images of the cathode layer. With vidicon or plumbicon tubes you can build a simpe scanning electron microscope for low magnification (~ 50..100). Sorry the pages are in german ...

Hi Johnf,
thanks a lot for the advice. So the motor ist driven by squarewaves rather than sinus.I will try to built this circuit. Maybe it will be difficult to get the 3-phase bridge driver ir2130 but I think it can be replaced by 3 single phase drivers. Perhaps if I had this information one year ...