Search found 1039 matches

by Rich Feldman
Thu Nov 12, 2020 6:47 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Grounding - neutral wire or grounding pin
Replies: 7
Views: 1257

Re: Grounding - neutral wire or grounding pin

There are two safety reasons why the grounding pin of every receptacle needs an intentional metallic path to the transformer secondary winding, and a locally driven earth ground rod or water pipe connection is insufficient. In NEC land, for new work; details depend on authority having jurisdiction. ...
by Rich Feldman
Tue Oct 20, 2020 2:09 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Heavy Water Usage (D2O)
Replies: 4
Views: 768

Re: Heavy Water Usage (D2O)

Very good. Do they put it up in 90 ml bottles, or in standard 100 ml bottles with more ullage? How careful are you all about handling D2O as a hygroscopic substance? I would guess that if the bottle sat for 10 minutes with cap off, the amount of normal H2O picked up is unlikely to exceed the amount ...
by Rich Feldman
Wed Oct 07, 2020 5:29 pm
Forum: Images du Jour
Topic: Looks old, works new
Replies: 0
Views: 715

Looks old, works new

Saw something the other day, reminiscent of vintage electronics restorations where ancient capacitors have been eviscerated & stuffed with modern ones. On the grounds of a local history museum, next to the water tank house and windmill, is a well pump with 1.5 HP electric motor. 20201004_173222.jpg ...
by Rich Feldman
Wed Sep 30, 2020 7:11 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: DEMO-FUSOR, How much can it take?
Replies: 4
Views: 925

Re: DEMO-FUSOR, How much can it take?

Hey Keelan, You asked whether your bell jar can withstand vacuum of 30 microns inside. By what factor is the stress greater than that on same jar with vacuum of 30 torrs inside? Assume the external pressure is 760 torrs in both cases. Not counting the risk of spot heating by electrified particle bea...
by Rich Feldman
Tue Sep 22, 2020 11:39 pm
Forum: Interesting Links
Topic: 3-D Model of a Stellarator Plasma
Replies: 7
Views: 932

Re: 3-D Model of a Stellarator Plasma

Natural gas prices are at historic lows because of fracking, and misguided federal approach to "energy independent USA". That means we are depleting our fixed reserves faster than ever. Short sighted, kind of like cutting taxes so USA is borrowing money from China faster than ever. My city council i...
by Rich Feldman
Sun Sep 20, 2020 10:28 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Diy high voltage probe
Replies: 5
Views: 895

Re: Diy high voltage probe

Nice work there; thanks for demonstrating by doing. It's OK to talk about using parts above their ratings. This is no worse than using MWO diodes to rectify a NST output, when operating PRV can be more than 21 kV. Electrical component abuse is a popular theme on Tesla coil forums. All are cases wher...
by Rich Feldman
Mon Sep 14, 2020 8:28 pm
Forum: Interesting Links
Topic: Possible Life in the upper atmosphere of Venus
Replies: 1
Views: 517

Re: Possible Life in the upper atmosphere of Venus

So Venus atmosphere balloon probe joins the throng of applicants competing for space probe funding. Other missions include the big metallic asteroid, Titan lake floater, Enceladus and Europa, etc. One that got approved, as discussed here a year or so ago, is the Titan lander / quadcopter that can fl...
by Rich Feldman
Sun Sep 13, 2020 7:37 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Restarting Efforts on Demo Fusor II
Replies: 25
Views: 2933

Re: Restarting Efforts on Demo Fusor II

Kuri is the same brand as my spiral hose. John's a practiced expert with vacuum stuff, and I'm lately just a pretender. Have never set up any diffusion or turbo pump with a backing pump. Need to clear a path to a work space for vacuum gear, not touched (except for opportunistic acquisitions) in abou...
by Rich Feldman
Sun Sep 13, 2020 7:03 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Restarting Efforts on Demo Fusor II
Replies: 25
Views: 2933

Re: Restarting Efforts on Demo Fusor II

Very cool, Ed. Back to vacuum gear and foreline connections, I finally dug out the vacuum hoses here. The ID of spiral-reinforced hose is 1/2 inch, and of thick rubber hose is a little less than 3/8 inch. Too small for the need you mentioned, but they are free to anyone who wants to pay the postage....
by Rich Feldman
Sun Sep 13, 2020 6:30 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: RF superimposed on HVDC
Replies: 3
Views: 739

Re: RF superimposed on HVDC

You need to start by specifying details like the RF impedance of the HV load, HV power source, and RF signal source. The series capacitor on RF-input branch obviously needs to hold off some kV, and will conduct glitches from HV arcs and sparks back to the RF signal source. The traditional inductor o...