Search found 124 matches

by AllenWallace
Sat Aug 27, 2011 12:51 am
Forum: Vacuum Technology (& FAQs)
Topic: Turbo pump spin down and venting
Replies: 11
Views: 6014

Turbo pump spin down and venting

<t>I have see several references that you should not let a turbo pump spin down without venting first. They say to vent during the spin down. Why should this be the case? Are they worried that a decompression might stress the blades? and why should this stress be any different stationary vs spinning...
by AllenWallace
Sun Aug 07, 2011 2:37 am
Forum: FAQs: High Voltage
Topic: FAQ: Neon transformer wiring diagram - demo fusor
Replies: 21
Views: 29233

Re: FAQ: Neon transformer wiring diagram - demo fusor

<t>Richard,<br/> <br/> I know that you are trying to keep the schematic simple and theoretical but perhaps we might add a diode across the voltage meter. If the 100M resistor arcs over, then the diode will protect the panel meter which is typically exposed to the the operator. <br/> <br/> Its possib...
by AllenWallace
Wed Jan 12, 2011 4:57 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: I Need Some Help With Grounding.
Replies: 14
Views: 4952

Re: I Need Some Help With Grounding.

<t>I'd also connect the chamber wall to the pump frame. This creates a ground loop, but this is not a problem because you are not using sensitive electronics and you are not carrying any current in your grounds. <br/> <br/> I'm not sure why you feel the need for a grounding rod, except that if you a...
by AllenWallace
Thu Jan 06, 2011 3:47 am
Forum: Vacuum Technology (& FAQs)
Topic: Re: Purchased welch 1402- no one can tell me if it works.
Replies: 2
Views: 1090

Re: Purchased welch 1402- no one can tell me if it works.

<t>James,<br/> <br/> Is this company local to the Idaho Falls area?<br/> <br/> In any case, how to measure high vacuum without a proper TC or similar gauge?<br/> <br/> Water boils at about 17 torr. This is way too high for fusor work, but if you wet the underside of a large rubber stopper (the kind ...
by AllenWallace
Fri Dec 24, 2010 3:46 am
Forum: Vacuum Technology (& FAQs)
Topic: Vacuum pump oil: where can it be found.
Replies: 8
Views: 3523

Re: Vacuum pump oil: where can it be found.

I found vacuum pump oil at my local farmers supply for about $20/Gal. Apparently cow milking machines use a vacuum pump. I used this as flushing oil and then used a 'proper' oil for the final oil in my Welch 1402.
by AllenWallace
Thu Aug 19, 2010 3:42 am
Forum: Vacuum Technology (& FAQs)
Topic: What is this? A oil trap? baffle?
Replies: 4
Views: 2446

What is this? A oil trap? baffle?

I got a Huntington CT-103 vacuum device. It was positioned between an oil diffusion pump and the rough pump. Can anyone tell me what this is? I'm assuming it prevents back streaming of oil from the rough pump.
by AllenWallace
Thu Aug 19, 2010 3:28 am
Forum: Vacuum Technology (& FAQs)
Topic: Varian 524 Clod Cathode Gauge?
Replies: 1
Views: 2577

Varian 524 Clod Cathode Gauge?

<t>I recently pulled a Varian 524-2 cold cathode gauge and controller from an old scanning electron microscope. A bit of web research suggests that the Varian 524 and 525 are similar. One PDF document suggests that you drive the tube with 2 KV and that the sensitivity is 2 amperes per Torr, from E-2...
by AllenWallace
Tue Apr 13, 2010 3:31 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: ICP coil first test
Replies: 43
Views: 12989

Re: ICP coil first test

A quick google search shows that to keep below the FCC radiation limit you should keep 9 feet away from a 14 Mhz dipole transmitting 1 KW.
by AllenWallace
Wed Feb 17, 2010 5:19 am
Forum: Vacuum Technology (& FAQs)
Topic: what is this vacuum pump?
Replies: 2
Views: 1620

Re: what is this vacuum pump?

I also think it's a Pfeiffer turbo pump. It may be a boat anchor unless you get a controller with it.
by AllenWallace
Tue Feb 02, 2010 2:52 am
Forum: Vacuum Technology (& FAQs)
Topic: Turbo pump paranoia
Replies: 9
Views: 2968

Re: Turbo pump paranoia

<t>Chris,<br/> <br/> When my son was working on is fusor, we saw a bugle jet electron beam travel down the vacuum piping to the Turbo Pump - and then the pump spun down never to start up again.<br/> <br/> You should consider a metal screen to cover the pump from debris and hopefully prevent errant e...