On Fri, 5 Oct 2012 07:43:56 -0700 (PDT), George Herold <gherold@teachspin.com> wrote:>Say does Don Klipstein still lurk here? He may have some info on turn- >on failure. >http://donklipstein.com/ >George H.Thanks. He has a section on why and how bulbs burn out at: <http://donklipstein.com/bulb1.html#how> -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Using mobile phone as an internet radio
Started by ●October 2, 2012
Reply by ●October 5, 20122012-10-05
Reply by ●October 5, 20122012-10-05
On 10/05/2012 06:20 AM, Roderick Stewart wrote:> In article<de99517e-e5e1-4f9d-91e0- > 412ab3171a05@o8g2000yqm.googlegroups.com>, George Herold wrote: >> And that�s it. Repeated on and off means that the thin region has a >> higher average temperature than the thick part of the filament. It >> evaporates faster and fails sooner. > > Won't a thin region of a lamp filament have a higher temperature than > the rest of it all the time, not just when the lamp is turning on? > > Rod. > -- >Thin spots will evaporate faster at all times, sure. The main question as to whether George's mechanism explains the alleged effect is whether, in a newish bulb, the inrush makes the hotspots exceed 2800K or whatever the normal filament temperature is, before the the inrush current subsides. I'd expect that to be more of a threshold effect, because the resistance of the filament ought to be pretty linear with temperature, whereas the evaporation essentially turns on at around 2500K, so the hot spots would have to be pretty thin already for it to do much. But as I say, I'm far from being a tungsten bulb expert myself. Cheers Phil Hobbs
Reply by ●October 5, 20122012-10-05
On 10/04/2012 07:11 PM, Dave Plowman (News) wrote:> In article<slrnk6ror4.jds.gsm@cable.mendelson.com>, > Geoffrey S. Mendelson<gsm@mendelson.com> wrote: >> Problem with that is my location. Shipping anything from anywhere except >> China is too expensive to make it worth while. A $10 (postage included) >> Samsung feed roller is worth buying, a part that does not fit in an >> envelope and has to go in a USPS box costs 1/2 to 1/3 the cost of a >> cheap Samsung printer. UPS/DHL/FDEDX double or tripple that price. > >> Also to be honest, the loss/theft rate from the US is too high to buy >> from unless it is via PayPal and eBay. > > Couple of years back I needed a new element for my Pace SX80 desolder > iron. Not one to be had in the UK. Got one from Pace US direct at not a > bad price - but they charged 40 gbp for P&P by courier - wouldn't send it > by post. So the delivered price was considerably more than the delivered > price from a UK supplier. If it had been coming from Hong Kong or China, > would have been less than half the price and free postage... > > There's lots of stuff I'd buy from the US if they would sort out their > postal service. I get the impression as much is stolen as delivered. >I've never had a package stolen, as far as I can recall. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●October 5, 20122012-10-05
On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>> Yep. As I understand it (possible wrong), AC filaments break in the >> middle, mostly from vibration flexing. > >I don't think so, because there's no mechanism for that, as I said. The >wire is fully annealed at all times, so there's no possibility of >progressive fatigue failure.Oscillating filament light bulb: <http://www.youtube.com/watch?v=t_DwwNVA-7Q> Whether the earths magnetic field is strong enough to induce such oscillations is questionable. While digging for the apparently mythical lifetime test data on incandescent light bulbs, I've found numerous theories on why filaments fail. Tungsten evaporation, causing hot spots, is the most common. One suggested that thermal cycling hardens the tungsten and makes it brittle. Another suggested that the inrush current causes a mechanical shock if it hits at the 60Hz peak, instead of at the zero crossing. Yet another speculates that the temperature differential between the hot filament, and the relatively cold mounting structure may cause cracking. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Reply by ●October 5, 20122012-10-05
George Herold wrote:> > Hmm, sure, maybe... I really have no idea. But I can't remember ever > seeing a bulb fail after being on for a while.It happens quite often in TV studios.
Reply by ●October 5, 20122012-10-05
On Oct 5, 2:51=A0pm, Jeff Liebermann <je...@cruzio.com> wrote:> On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs > > <pcdhSpamMeSensel...@electrooptical.net> wrote: > >> Yep. =A0As I understand it (possible wrong), AC filaments break in the > >> middle, mostly from vibration flexing. > > >I don't think so, because there's no mechanism for that, as I said. =A0T=he> >wire is fully annealed at all times, so there's no possibility of > >progressive fatigue failure. > > Oscillating filament light bulb: > <http://www.youtube.com/watch?v=3Dt_DwwNVA-7Q> > Whether the earths magnetic field is strong enough to induce such > oscillations is questionable. > > While digging for the apparently mythical lifetime test data on > incandescent light bulbs, I've found numerous theories on why > filaments fail.Grin, the internet as a 'fire hose' of information. I went searching for something that contained "Philips tech. rev." and found a reference to the following article, H. Horster, E. Kauer and W. Lechner =97 The Burn-out Mechanism of Incandescent Lamps Philips Technical Review 32,155-164, 1971. It was referenced in "Illuminating Engineering - Page 32 - Google Books" But nothing about turn on failure... sigh. Here is a patent by some of the same guys at Philips... lots of stuff about the filament getting hottest in the middle. http://www.freepatentsonline.com/3868159.html (Actually a decently written patent.) George H. Tungsten evaporation, causing hot spots, is the most> common. =A0One suggested that thermal cycling hardens the tungsten and > makes it brittle. =A0Another suggested that the inrush current causes a > mechanical shock if it hits at the 60Hz peak, instead of at the zero > crossing. =A0Yet another speculates that the temperature differential > between the hot filament, and the relatively cold mounting structure > may cause cracking. > > -- > Jeff Liebermann =A0 =A0 je...@cruzio.com > 150 Felker St #D =A0 =A0http://www.LearnByDestroying.com > Santa Cruz CA 95060http://802.11junk.com > Skype: JeffLiebermann =A0 =A0 AE6KS =A0 =A0831-336-2558G
Reply by ●October 5, 20122012-10-05
Phil Hobbs wrote:> > I've never had a package stolen, as far as I can recall.Me, either. It's probably that their postal system won't come to reasonable terms with the US postal system.
Reply by ●October 5, 20122012-10-05
Jeff Liebermann wrote:> > On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > > >> Yep. As I understand it (possible wrong), AC filaments break in the > >> middle, mostly from vibration flexing. > > > >I don't think so, because there's no mechanism for that, as I said. The > >wire is fully annealed at all times, so there's no possibility of > >progressive fatigue failure. > > Oscillating filament light bulb: > <http://www.youtube.com/watch?v=t_DwwNVA-7Q> > Whether the earths magnetic field is strong enough to induce such > oscillations is questionable. > > While digging for the apparently mythical lifetime test data on > incandescent light bulbs, I've found numerous theories on why > filaments fail. Tungsten evaporation, causing hot spots, is the most > common. One suggested that thermal cycling hardens the tungsten and > makes it brittle. Another suggested that the inrush current causes a > mechanical shock if it hits at the 60Hz peak, instead of at the zero > crossing. Yet another speculates that the temperature differential > between the hot filament, and the relatively cold mounting structure > may cause cracking. > > --All of those except the hot spot mechanism assume that the tungsten work-hardens in the bulb and then fails from fatigue. However, that isn't the case, because the annealing temperature of tungsten is about 1300 C, so the tungsten in a light bulb filament is always fully annealed. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●October 5, 20122012-10-05
George Herold wrote:> > On Oct 5, 2:51 pm, Jeff Liebermann <je...@cruzio.com> wrote: > > On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs > > > > <pcdhSpamMeSensel...@electrooptical.net> wrote: > > >> Yep. As I understand it (possible wrong), AC filaments break in the > > >> middle, mostly from vibration flexing. > > > > >I don't think so, because there's no mechanism for that, as I said. The > > >wire is fully annealed at all times, so there's no possibility of > > >progressive fatigue failure. > > > > Oscillating filament light bulb: > > <http://www.youtube.com/watch?v=t_DwwNVA-7Q> > > Whether the earths magnetic field is strong enough to induce such > > oscillations is questionable. > > > > While digging for the apparently mythical lifetime test data on > > incandescent light bulbs, I've found numerous theories on why > > filaments fail. > > Grin, the internet as a 'fire hose' of information. I went searching > for something that contained "Philips tech. rev." and found a > reference to the following article, > > H. Horster, E. Kauer and W. Lechner � The Burn-out Mechanism of > Incandescent Lamps Philips Technical Review 32,155-164, 1971. > > It was referenced in "Illuminating Engineering - Page 32 - Google > Books" > > But nothing about turn on failure... sigh. > > Here is a patent by some of the same guys at Philips... lots of stuff > about the filament getting hottest in the middle. > > http://www.freepatentsonline.com/3868159.html > (Actually a decently written patent.) > > George H. > > Tungsten evaporation, causing hot spots, is the most > > common. One suggested that thermal cycling hardens the tungsten and > > makes it brittle. Another suggested that the inrush current causes a > > mechanical shock if it hits at the 60Hz peak, instead of at the zero > > crossing. Yet another speculates that the temperature differential > > between the hot filament, and the relatively cold mounting structure > > may cause cracking. > >I can believe that the filament is hottest in the middle. It's furtherst from the support, so whatever conductive heat sinking there is will be less, but more than that, it sees the radiative input from the rest of the filament on both sides instead of just one. Sort of similar to the case of a long solenoid, whose B field at the ends is half what it is in the middle. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●October 5, 20122012-10-05
In article <GcKdnTpQbqR-ofLNnZ2dnUVZ_sqdnZ2d@earthlink.com>, Michael A. Terrell <mike.terrell@earthlink.net> wrote:> Phil Hobbs wrote: > > > > I've never had a package stolen, as far as I can recall.> Me, either. It's probably that their postal system won't come to > reasonable terms with the US postal system.Other countries seem quite happy to use ordinary post to the UK. The US, not. So explain that. -- *Never put off until tomorrow what you can avoid altogether * Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound.
