Search found 977 matches

by Rich Feldman
Tue Sep 18, 2018 4:29 pm
Forum: The Trading Post
Topic: Stuff for sale at Halted Supply in San Jose, California
Replies: 3
Views: 129

Re: Stuff for sale at Halted Supply in San Jose, California

Oh that's sad news, Ian, but does not come as a big surprise.
A recent bolt from the blue was announcement that whole Orchard Supply Hardware chain is closing.
by Rich Feldman
Tue Sep 11, 2018 11:32 pm
Forum: Images du Jour
Topic: My first plasma
Replies: 12
Views: 982

Re: My first plasma

What if the chamber were lined with a non-structural metal screen that you can see through? For example, fine woven wire cloth like that in fuel filters. Or perforated sheet metal like in microwave oven doors. If the holes are small enough, and/or optical transparency low enough, ion beams and e-bea...
by Rich Feldman
Mon Sep 10, 2018 2:58 am
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Neon sign transformer power: a new look
Replies: 7
Views: 1391

Re: Neon sign transformer power: a new look

Yes, my tiny LED panel meters are from ebay for $2 or $3 each. Could have got some about the same for $7 at the flea market. The voltmeters are all 0 to +30 with three wires; negative power and negative V_in share a wire. The ammeters (in various ranges) have built-in shunts and four wires (two thin...
by Rich Feldman
Sun Sep 09, 2018 11:08 pm
Forum: Images du Jour
Topic: Sharing hamfest booty images
Replies: 27
Views: 5241

Re: Sharing hamfest booty images

Yes yes & yes. I was picky about the free meters, and at least one looked like it had radium paint. Haven't tried lighting up the funny little diode. The valve does have those face-seal connectors, including a metal dent protector under one of the plastic dust caps. The rectifier says JAN-249? (prob...
by Rich Feldman
Sun Sep 09, 2018 5:30 am
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Neon sign transformer power: a new look
Replies: 7
Views: 1391

Re: Neon sign transformer power: a new look

Here's a preview of a 100 mA AC/DC digital panel meter, put together much more quickly than the kilovoltmeter in OP. I hope it can serve on the high side of multi-kV circuits, like NST's and color TV sets, when put in a compact enclosure with an anti-corona shape. Other high side metering options in...
by Rich Feldman
Sun Sep 09, 2018 4:55 am
Forum: Images du Jour
Topic: Sharing hamfest booty images
Replies: 27
Views: 5241

Re: Sharing hamfest booty images

The electronics flea market in Sunnyvale (formerly Cupertino), CA ended its 2018 season today. Alas, demands of my day job left no time to pack up for selling. Double alas, I went anyway, and fell into binge mode. Brought home many things that are small and inexpensive, or small and free. Here are a...
by Rich Feldman
Thu Aug 30, 2018 2:14 am
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Neon sign transformer power: a new look
Replies: 7
Views: 1391

Re: Neon sign transformer power: a new look

Yes, what John said. Sorry about posting a chart without labeling the curves. This little transformer is responsible for first set of data from my lab. The device, and the method, are described a couple of posts ago. DSCN0803.JPG Core laminations have no joints on the outside perimeter. Looks like t...
by Rich Feldman
Mon Aug 27, 2018 11:48 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Neon sign transformer power: a new look
Replies: 7
Views: 1391

Re: Neon sign transformer power: a new look

Just got clear on something that should've been obvious, and on which I speculated in prev. post. The simple linear model of "AC voltage source with series inductance" yields an I-V curve that's one quadrant of a circle. That's because the voltage drop due to leakage inductance is in quadrature with...
by Rich Feldman
Mon Aug 27, 2018 5:56 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Neon sign transformer power: a new look
Replies: 7
Views: 1391

Re: Neon sign transformer power: a new look

Just found another 15-year-old thread about NST characteristics, on this very forum. It contains lots of information and some arguing. http://www.fusor.net/board/viewtopic.php?t=4315 It even includes John DeArmond, "Neon John", whom I remember from pre-Internet Usenet days (1993-1994). I've still no...
by Rich Feldman
Fri Aug 24, 2018 10:34 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Neon sign transformer power: a new look
Replies: 7
Views: 1391

Neon sign transformer power: a new look

This is to re-open the topic of power output from neon sign transformers. The most detail I've seen previously is Richard's old paper, neons.doc, linked in a HV FAQ thread called "#8 FAQ - Neon transformers - the facts". http://www.fusor.net/board/viewtopic.php?f=29&t=10333 One rule of thumb, from t...