Search found 158 matches

by Peter Schmelcher
Fri May 18, 2018 9:17 pm
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: lab electromagnet from scratch
Replies: 58
Views: 18687

Re: lab electromagnet from scratch

I believe you should split the electromagnetic, half around the top and half around the bottom. This should change the magnetic circuit potential in the support arms to zero opposite the air gap, the reduced coil diameter requires less wire so you will get more amp turns from your spool. My fading m...
by Peter Schmelcher
Fri May 04, 2018 8:41 am
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.56MA
Replies: 155
Views: 29119

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

Using Andrews connector autopsy as a starting point I printed a Claymount style HV connector in PLA. It’s a work in progress but basically you cast silicone between a PLA shell and the HV cable to eliminate any air voids between the cable and the shell. The HV connector plug has a 0.5degree taper so...
by Peter Schmelcher
Sat Apr 21, 2018 9:11 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Detector noise problem
Replies: 13
Views: 2758

Re: Detector noise problem

Try disconnecting the HV tube bias supply and cap or short the connection.
by Peter Schmelcher
Fri Apr 20, 2018 6:41 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Detector noise problem
Replies: 13
Views: 2758

Re: Detector noise problem

Looking for EMI is a witch hunt and your coupling could be M or E field or simply conducted. If it were me I would float the preamp with a 9V battery and only connect the scope to begin the hunt. If I could float the scope on batteries I would and also position it on a plastic shelf. Then start intr...
by Peter Schmelcher
Mon Dec 04, 2017 6:44 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Vacuum Pressure controller (Edwards) or cheaper pressure controller
Replies: 4
Views: 688

Re: Vacuum Pressure controller (Edwards) or cheaper pressure controller

I would recommend a full pressure range inverted magnetron like an MPG401. This gauge is re branded and sold by several vacuum outfits, I do not know who the original manufacturer is, no markings on the internal circuit boards provide a hint. I got my Inficon MPG401 some time ago for $100 and it was...
by Peter Schmelcher
Wed Nov 22, 2017 7:10 pm
Forum: Images du Jour
Topic: Fusor progress, Finn Hammer
Replies: 25
Views: 4124

Re: Fusor progress, Finn Hammer

Finn I tested the same tube without any moderator (at sea level) some time ago and decided on proportional operation by using a 1000 volt tube bias. One drawback you can see in the scope capture is that the neutron pulse output amplitude is smaller so shielding the electronics becomes more important...
by Peter Schmelcher
Sun Oct 01, 2017 12:49 am
Forum: Vacuum Technology (& FAQs)
Topic: My Turbo and Homemade Driver
Replies: 16
Views: 2462

Re: My Turbo and Homemade Driver

Niels attached are some pics of a tph 055 that might provide some useful insights for your repair. Mine was missing the other bottom parts when I got it. BTW the tph magnetic bearing also has a 6x13mm ball bearing for takeoff and landing. I investigated high speed ball bearings some time ago. The on...
by Peter Schmelcher
Tue Apr 11, 2017 6:54 pm
Forum: Vacuum Technology (& FAQs)
Topic: Leak Troubles
Replies: 32
Views: 4431

Re: Leak Troubles

If your gauge works fine at higher pressures and then stops as the pressure drops you might have a magnetic field strength problem. If you adjust the magnet position and center it over the cell it might operate to a lower pressure. It is also possible heat has demagnetized the magnet. The voltage be...
by Peter Schmelcher
Fri Mar 31, 2017 5:19 pm
Forum: Vacuum Technology (& FAQs)
Topic: Leak Troubles
Replies: 32
Views: 4431

Re: Leak Troubles

Tom have you tested your penning gauge electrical feedthroughs as they can leak, mine did and on a nearby part I had a cracked weld. Wrap nearby or all fittings with plastic wrap and/or tape. This helps reduce dust off overspray when hunting for multiple leaks and if possible bag your gauge in secti...
by Peter Schmelcher
Thu Mar 23, 2017 5:56 pm
Forum: New User Chat Area
Topic: Small "bump" or defect on VCR Swagelok fitting?
Replies: 3
Views: 739

Re: Small "bump" or defect on VCR Swagelok fitting?

I have one VCR face that has a big dimple on my MFC output fitting. I just stacked two washers. Don’t over tighten, do a leak test and tighten some more if necessary. Also if you use non standard thickness washers, measure the connector thread and calculate how many turns the washer thickness is and...