Search found 980 matches

by Rich Feldman
Wed Apr 08, 2020 3:32 am
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Peculiar High Voltage Transformer
Replies: 3
Views: 149

Re: Peculiar High Voltage Transformer

Welcome! Standard advice 1: don't abuse HV transformers (other than NST) by drawing arcs in air, if you intend to use them for more than arc play. Especially if you are not proficient with ballasting. Consider big x-ray transformers, like those used by chiropractors instead of dentists. Operating po...
by Rich Feldman
Mon Apr 06, 2020 7:49 pm
Forum: Announcements and Site Administration Topics
Topic: Coronavirus pandemic
Replies: 57
Views: 2930

Re: Coronavirus pandemic

Plain numerology continues to show easing of the expansion rate. Light at end of tunnel ? They say Germany is getting there. cdc2.jpg Of course one must consider the trustworthiness of numbers out of any place where government science output is politically filtered. Planning for disease epidemics ha...
by Rich Feldman
Mon Apr 06, 2020 5:07 pm
Forum: Announcements and Site Administration Topics
Topic: Coronavirus pandemic
Replies: 57
Views: 2930

Re: Coronavirus pandemic

Yes, sewing machines are busy. My sister found some extra work for hers. IMG_7432.jpg I cleaned out a corner of garage that had been untouched for a few years. Found a household radiation-dosimeters kit for which I had a use right away. rad1.jpg rad2.jpg Looks like us Dicks have a common interest. W...
by Rich Feldman
Sun Apr 05, 2020 7:05 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Simple Cold Trap for PEM Cell Deuterium
Replies: 3
Views: 115

Re: Simple Cold Trap for PEM Cell Deuterium

Wow! Is the neutron yield up 50% or a factor of two? You mentioned same power input. Have you ruled out changes in the plasma pressure? Have you tried measuring the water content of gas coming from PEM cell? I bet electronic humidity sensors would work. Or make a dew-point checker. How 'bout a small...
by Rich Feldman
Thu Apr 02, 2020 10:11 pm
Forum: Announcements and Site Administration Topics
Topic: Coronavirus pandemic
Replies: 57
Views: 2930

Re: Coronavirus pandemic

Aha! What if we are entangled? I came to put up more numbers, with references, instead of anecdotes or philosophy or humor. The log-chart option has returned to JHU interactive map page, and is now joined by ability to make it USA-specific. This snip is for USA only, which needs no help plowing thro...
by Rich Feldman
Sat Mar 28, 2020 11:33 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Keithley picoammeter manuals?
Replies: 5
Views: 431

Re: Keithley picoammeter manuals?

While sheltering at home, with weekend immune system, took the opportunity to fire up the other picoammeter without benefit of a manual. Same current reference: 9V battery and 5000 megohm resistor, which indicated as + or - a little less than 2 nA on the model 480. k26000_2.jpg With no current, the ...
by Rich Feldman
Sat Mar 28, 2020 5:18 pm
Forum: Announcements and Site Administration Topics
Topic: Coronavirus pandemic
Replies: 57
Views: 2930

Re: Coronavirus pandemic

[edit Saturday morning] Suppose Covid-19 wins this horse race when its death count (in USA) surpasses the upper estimate for regular flu deaths (62K). At the rate we are going, that will happen when the number of reported Covid infections reaches 4 or 5 million. But of those 62K deaths chalked up to...
by Rich Feldman
Fri Mar 27, 2020 11:31 pm
Forum: Announcements and Site Administration Topics
Topic: Coronavirus pandemic
Replies: 57
Views: 2930

Re: Coronavirus pandemic

The JHU coronavirus map lost its logarithmic chart option. Then I found USA-oriented data at CDC website, https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/cases-in-us.html and drew my own chart. The times-10 interval isn't 2 weeks, as we saw in global chart, it's a little less than 10 days. :...
by Rich Feldman
Thu Mar 26, 2020 5:19 pm
Forum: Images du Jour
Topic: Reverse engineering a big old smoke detector
Replies: 8
Views: 748

Re: Reverse engineering a big old smoke detector

The slope of linear section, with reverse bias, matches a resistance of almost 200 gigaohms. Even higher in the presence of smoke, or as the voltage approaches saturation. We have seen, here and in Richard's electrometer device thread, that neon-filled trigger tubes can switch whole milliamps accord...
by Rich Feldman
Wed Mar 25, 2020 6:29 pm
Forum: Images du Jour
Topic: Reverse engineering a big old smoke detector
Replies: 8
Views: 748

Re: Reverse engineering a big old smoke detector

Got some ion chamber current measurements this morning. Both chambers in series, without disconnecting the untriggered cold cathode tube. Black wire from edge of picture connects power supply chassis to a grounding conductor. 20200325_110836.jpg . The shape matches what's shown in textbook. We see s...