Search found 84 matches

by Bruce Meagher
Wed Jan 17, 2018 10:46 pm
Forum: New User Chat Area
Topic: Serial communication
Replies: 14
Views: 447

Re: Serial communication

Like Finn mentioned above, with an oscilloscope and the known working PC connection you could quickly debug this issue. It can be challenging in high school to get access to even the most basic test equipment. If you haven’t done so already, I’d highly recommend finding a mentor with access to this ...
by Bruce Meagher
Tue Jan 16, 2018 1:48 am
Forum: Images du Jour
Topic: Arc polarity for fusing wire?
Replies: 6
Views: 271

Re: Arc polarity for fusing wire?

I tried this on my tig welder. A little alligator clip to attached the wire to the tungsten tip, and then a little zap. Tried both electrode positive and negative and both came out soft but I had argon flowing into the cup. I'd imagine your timer method should produce nice consistent sized balls. IM...
by Bruce Meagher
Mon Jan 15, 2018 5:36 am
Forum: New User Chat Area
Topic: Serial communication
Replies: 14
Views: 447

Re: Serial communication

I believe Pablo has a custom built cable where a separate 9-30V power supply is spliced in (see the Y in his custom cable) to power the 901p on pins 3 and 4. Pablo, what pins did you connected on your custom DB-9 to DB-15 cable, and are the shells connected? A little diagram would clear up any confu...
by Bruce Meagher
Sun Jan 14, 2018 7:32 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: A Bunch of Failures
Replies: 46
Views: 1262

Re: A Bunch of Failures

The small added volume doesn’t matter. In fact, an excellent exercise is to calculate approximately how long it should take to pump down to 100 mtorr (assuming no leaks and no outgassing). (hint: for your test system with the E2M5 the number should be less than 15 second). You’re not reaching this l...
by Bruce Meagher
Sun Jan 14, 2018 3:11 pm
Forum: New User Chat Area
Topic: Serial communication
Replies: 14
Views: 447

Re: Serial communication

As Jerry mentions your Arduino serial read is most likely timing out (default is 1 second), and that’s why you are not displaying a pressure value on the LCD. There's nothing wrong with your code that's causing a problem, but a simple check if the string is of zero length and displaying an error wou...
by Bruce Meagher
Sat Jan 13, 2018 9:33 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: A Bunch of Failures
Replies: 46
Views: 1262

Re: A Bunch of Failures

When you ballast the pump you only crack open the cap a turn or so. You don’t actually physically remove the cap. You appear the have 7 connections between the pump and your gauge that are possible leak sources. Is the male 1/4” NTP just above your KF-25 adapter wrapped with teflon tape (it doesn’t ...
by Bruce Meagher
Fri Jan 12, 2018 4:46 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: A Bunch of Failures
Replies: 46
Views: 1262

Re: A Bunch of Failures

Try running with gas ballast open for 15 mins and then closed for an hour. Then repeat once and report for findings. Also include a pic of your test setup. Make sure you’re in a well ventilated area to protect your little lungs.
by Bruce Meagher
Tue Jan 09, 2018 7:37 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: A Bunch of Failures
Replies: 46
Views: 1262

Re: A Bunch of Failures

I’d worry more about the vapor pressure of the cheap oil and the implications of using it in your newly purchased pump.
by Bruce Meagher
Sun Jan 07, 2018 7:47 pm
Forum: Vacuum Technology (& FAQs)
Topic: Severe Outgassing Problems
Replies: 7
Views: 232

Re: Severe Outgassing Problems

Erik, As Jerry and Richard mentioned for a fusor this level of outgassing isn’t an issue. However, I’m kinda like you in that I want to understand what’s happening and why. Here are a couple things you might consider. When plasma cleaning you need to be pumping, not valved off like you mention above...
by Bruce Meagher
Thu Jan 04, 2018 3:23 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Ludlum 12 Ratemeter Issues
Replies: 10
Views: 370

Re: Ludlum 12 Ratemeter Issues

I’ve had many problems with Ludlum's battery compartment causing faulty or flakey power to the electronics on their old meters. When in doubt check the power at the the board with a DMM. The most common problems I’ve seen are oxidized terminals (top and bottom) and faulty springs. It might not be th...