Search found 49 matches

by Cai Arcos
Thu Feb 13, 2020 10:49 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Help with HV adjustable power supplies for radiation detectors.
Replies: 24
Views: 3225

Re: Help with HV adjustable power supplies for radiation detectors.

John: In the end, I actually recreated one of the schematics posted in the attached posts and buffered the feedback. Probably due to the very limited slew rate of the LM324, no oscillations happened, an it fact the noise is now under control. Adding the speed capacitor actually reduces a little bit ...
by Cai Arcos
Sun Feb 09, 2020 11:35 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Help with HV adjustable power supplies for radiation detectors.
Replies: 24
Views: 3225

Re: Help with HV adjustable power supplies for radiation detectors.

John: I problem I've noticed when using Rc and Cc: after leaving the circuit for around 2 or 3 minutes, the noise increases dramatically. I post the noise measurement with different values of Rc and Cc used and the result. It seems as this is the phenomena I was first describing. It seems as if the ...
by Cai Arcos
Sun Feb 09, 2020 11:14 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Help with HV adjustable power supplies for radiation detectors.
Replies: 24
Views: 3225

Re: Help with HV adjustable power supplies for radiation detectors.

Rich: I had found two posts regarding CCFL inverters: https://fusor.net/board/viewtopic.php?f=13&t=12097&p=78757&hilit=CCFL#p78757 https://fusor.net/board/viewtopic.php?f=11&t=4775&p=31184&hilit=CCFL#p31184 In Doug Coulter's Forums there is also extensive discussion on noise and such: the problem is...
by Cai Arcos
Sun Feb 09, 2020 11:00 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Help with HV adjustable power supplies for radiation detectors.
Replies: 24
Views: 3225

Re: Help with HV adjustable power supplies for radiation detectors.

John: I wrote this late at night and made an important mistake. The Rc and Cc components don't introduce oscillation. I thought so because I tested the whole circuit when using the zener diode (the source of noise). I have now included them back and the circuit works the same way (it didn't oscillat...
by Cai Arcos
Sat Feb 08, 2020 9:51 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Help with HV adjustable power supplies for radiation detectors.
Replies: 24
Views: 3225

Help with HV adjustable power supplies for radiation detectors.

Hi: I'm in the process of building a variable (0-600V), relatively silent (400mV peak to peak noise maximum) and able to sustain it's output voltage under a 1Mega omh load power supply for work in development of radiation detectors. The schematic I post have achieved that, with a noise of around 360...
by Cai Arcos
Thu Jan 16, 2020 4:58 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Development of HV smps
Replies: 3
Views: 961

Re: Development of HV smps

At least for me, buying it simply takes away the fun of it (although HV PSUs are way more interesting to me than the fusor, so that might not be shared by more here). I'm aware that flybacks, even those from old TVs, are not able to supply the required current. Have you tried however to measure the ...
by Cai Arcos
Thu Jan 09, 2020 2:15 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Magnetically assisted ionization
Replies: 14
Views: 2003

Re: Magnetically assisted ionization

That's interesting. It should be expected that at higher energies the effect is reduced due to the smaller gyration radius for the same magnetic field. However, in the original post Joe is working with 70kV, while Jon is using 40kV. How can its effect be more noticeable in the first case? Am I missi...
by Cai Arcos
Thu Jan 09, 2020 8:23 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Magnetically assisted ionization
Replies: 14
Views: 2003

Re: Magnetically assisted ionization

Hi:
Joe Gayo actually used an axial magnetic field in his superb work:

viewtopic.php?f=6&t=12826&p=83473#p83473
by Cai Arcos
Sun Dec 15, 2019 9:49 am
Forum: FAQs: Vacuum Technology
Topic: FAQ - Paschen, gas, vacuum, electrostatics, break down, etc., etc.
Replies: 7
Views: 1079

Re: FAQ - Paschen, gas, vacuum, electrostatics, break down, etc., etc.

Hi: In the article of Wikipedia regarding smoke detectors, it is stated that: In 1939 Swiss physicist Ernst Meili devised an ionization chamber device capable of detecting combustible gases in mines.[8] He also invented a cold cathode tube that could amplify the small signal generated by the detecti...
by Cai Arcos
Sat Dec 14, 2019 7:47 pm
Forum: FAQs: Vacuum Technology
Topic: FAQ - Paschen, gas, vacuum, electrostatics, break down, etc., etc.
Replies: 7
Views: 1079

Re: FAQ - Paschen, gas, vacuum, electrostatics, break down, etc., etc.

Richard: What an interesting device indeed! I have a little fascination with the measurement of small currents using vacuum tubes, and because of that have read a lot of papers regarding the so called "electrometer tubes", as well as others that discussed the use of common receiver tubes like the Ty...