Search found 1221 matches

by John Futter
Mon Mar 30, 2020 9:16 pm
Forum: Vacuum Technology (& FAQs)
Topic: Leak in vacuum system (diffusion pump?)
Replies: 12
Views: 973

Re: Leak in vacuum system (diffusion pump?)

could have been off a SEM
As you are not going to use the cold trap (the bit directly above your diff stack) take it off
they are notorious for springing leaks due to the excessive thermal cycling they undergo
by John Futter
Mon Mar 30, 2020 9:09 am
Forum: Vacuum Technology (& FAQs)
Topic: Leak in vacuum system (diffusion pump?)
Replies: 12
Views: 973

Re: Leak in vacuum system (diffusion pump?)

you need to divide and conquer ie you need to shift your conflat 2.75 blank to the end of your flexible hose that is just before your pirani you need to shift the pirani to the other side of this is this alright then reconnect if not suspect all joints beforehand and so the story unfolds far too man...
by John Futter
Fri Mar 27, 2020 6:35 am
Forum: Images du Jour
Topic: Nathan Marshall - Fusor Progress
Replies: 41
Views: 3447

Re: Nathan Marshall - Fusor Progress

Nathan
nice setup
not sure you require the fancy banyard alpert gauge head but good find
your demo pics are first class
by John Futter
Mon Mar 23, 2020 12:49 am
Forum: Interesting Links
Topic: "Nuclear Physics Lab" Website
Replies: 4
Views: 482

Re: "Nuclear Physics Lab" Website

Yes again http not https
my isp is blocking all insecure sites until the COVID 19 emergency is over due to low lifes exploiting vulnerable people with miracle cures etc
by John Futter
Mon Mar 23, 2020 12:44 am
Forum: Vacuum Technology (& FAQs)
Topic: March issue of the bell jar - HV supply article
Replies: 5
Views: 664

Re: March issue of the bell jar - HV supply article

Its a pity the bell jar is not https as this is what happens Your Internet access is blockedFirewall or antivirus software may have blocked the connection. Try: Checking the connection Checking firewall and antivirus configurations Running Windows Network Diagnostics ERR_NETWORK_ACCESS_DENIED this i...
by John Futter
Sun Mar 22, 2020 5:49 pm
Forum: Interesting Links
Topic: "Nuclear Physics Lab" Website
Replies: 4
Views: 482

Re: "Nuclear Physics Lab" Website

I tried it but

site cannot be reached message popped up
by John Futter
Wed Mar 18, 2020 5:39 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: HF switcher supply construction and voltage multiplication
Replies: 25
Views: 2874

Re: HF switcher supply construction and voltage multiplication

again no base or C,E protection
probably more silicon sacrifice to the gods of high voltage
by John Futter
Tue Mar 17, 2020 5:58 am
Forum: Announcements and Site Administration Topics
Topic: Coronavirus pandemic
Replies: 100
Views: 8886

Re: Coronavirus pandemic

Alcohol concentration has to be greater than 60 % to be effective
do not scrimp on the alcohol pays to go a little greater in strength

now for some humour
aussie_catch.jpg
loo_paper_shortage.jpg
by John Futter
Sat Mar 07, 2020 10:03 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Vacuum Chamber Construction
Replies: 82
Views: 27128

Re: Vacuum Chamber Construction

Nicolas I would srongly suggest you do a pressure test on your chamber first. Ie blank off everthing and feed shop air at 15psi (no more)into your chamber through your gas feed line Use 50:50 detergent and water and go round every weld and vacuum joint with a small paint brush dipped in the detergen...
by John Futter
Fri Mar 06, 2020 1:27 am
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: HF switcher supply construction and voltage multiplication
Replies: 25
Views: 2874

Re: HF switcher supply construction and voltage multiplication

Victor is on the right track I see that you have not provided any protection for the transistor bases or collectors. Any transformer with a large ratio will have relatively high leakage inductance which will cause reflected high voltage artifacts into the primary this via capacitive coupling so ther...