Search found 693 matches

by Andrew Seltzman
Sat Aug 11, 2018 12:14 am
Forum: The Trading Post
Topic: 10x CHEAP TURBOS w/ controller (Pfeiffer TMH 261) on ebay ~$50
Replies: 9
Views: 491

Re: 10x CHEAP TURBOS w/ controller (Pfeiffer TMH 261) on ebay ~$50

$300-360 for the first 3, which for a turbo with a built in controller and a 30 day right of return actually IS a really good deal. If it dosen't work you can return it, which is more then you typically get with even more expensive turbos.
by Andrew Seltzman
Thu Aug 09, 2018 2:12 pm
Forum: The Trading Post
Topic: 10x CHEAP TURBOS w/ controller (Pfeiffer TMH 261) on ebay ~$50
Replies: 9
Views: 491

10x CHEAP TURBOS w/ controller (Pfeiffer TMH 261) on ebay ~$50

There are about 10 Pfeiffer TMH 261 Turbomolecular Vacuum Pumps with controllers on ebay ending within a few days, the bidding is at ~$30-$50 on them so far. Due to the large quantity the ending bids might be low (for a turbo). Now is the time if you want one. https://www.ebay.com/sch/m.html?_odkw=p...
by Andrew Seltzman
Sun Jul 08, 2018 10:18 pm
Forum: The Trading Post
Topic: Re: Andrew Seltzman's for sale list updated (3/8/2018)
Replies: 4
Views: 5300

Re: Andrew Seltzman's for sale list updated (7/8/2018)

New hardware on ebay:
https://www.ebay.com/sch/rtftechnologie ... 7675.l2562
Send me an email at andrewseltzman <at> gmail.com (for a better deal/combined shipping) if you are interested in any of the items.
by Andrew Seltzman
Sun Jul 08, 2018 9:50 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Mark3 operation 3e-4 torr / quad ion source @ -40kV, 1mA-9mA
Replies: 132
Views: 32429

Re: Mark3 operation and upgrades

A recent upgrade to the mark 3 has replaced the 6 way conflat cube with an 8 way kimball physics vacuum hexagon. The hexagon is considerably smaller and more compact, and has 2 more ports then the cube. The hexagon is connected to the core with a brazed ceramic isolator with copper conflat o-rings, ...
by Andrew Seltzman
Thu Jul 05, 2018 11:12 pm
Forum: Books & References
Topic: Answer keys w/ explanation?
Replies: 19
Views: 1487

Re: Answer keys w/ explanation?

This is the rutherford scattering problem: http://hyperphysics.phy-astr.gsu.edu/hbase/Nuclear/elescat.html It means assume the atom is free space except for the nucleus which is solid sphere. Calculate the radius of the nucleii and thus the area each nucleii is blocking. Find how thick a foil is req...
by Andrew Seltzman
Thu Jun 07, 2018 12:37 pm
Forum: The Trading Post
Topic: MKS 901p vacuum gauges
Replies: 7
Views: 1571

Re: MKS 901p vacuum gauges

Teraterm is a good terminal program, use a USB-serial adapter if you don't have a port. The DB15HD is just a VGA style connector, they are really easy to get.
by Andrew Seltzman
Sat Jun 02, 2018 1:08 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.56MA
Replies: 155
Views: 26071

Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.56MA

I don't see an attached plot, could you upload the plot and the text output printed to the matlab terminal?

It sounds like one of the interlocks is tripped, do you have the proper pins jumpered on the 15pin connector?

The java applet is really old and dosen't work on current OS.
by Andrew Seltzman
Wed May 23, 2018 9:49 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: TIG welding tubing and flanges with an automated fixture
Replies: 8
Views: 2208

Re: TIG welding tubing and flanges with an automated fixture

The chuck is capable of continuous rotation, the wire on the jaw connects to the chuck body so weld current dosen't flow through the jaw ways or scroll. The current then flows down the drawbar (a 1/4-20 bolt) which is insulated from the gearbox so current doesn't flow through the worm gear or bearin...
by Andrew Seltzman
Wed May 23, 2018 12:43 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: TIG welding tubing and flanges with an automated fixture
Replies: 8
Views: 2208

TIG welding tubing and flanges with an automated fixture

I have recently built a welding lathe for automated tube welding for an upgrade to my fusor. The lathe holds a TIG torch at a fixed distance from the tube or flange and rotates the part at a constant speed. A current path is provided through the chuck drawbar which is insulated from the gearbox. The...