aluminum heatsink anodizing
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From: John Devereux on 20 Dec 2008 12:51 John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> writes: > On Sat, 20 Dec 2008 10:58:28 +0000, John Devereux > <john(a)devereux.me.uk> wrote: > >>John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> writes: >> [...] >>> What's amazing is that you can tool up a die and buy a truckload of >>> custom extrusion for nearly the price of the aluminum, which may be a >>> fifth the price you'd pay for a similar stock extrusion from a >>> "heatsink" company. >>> >>> Ditto sheet metal. We can do a custom chassis, exactly the way we want >>> it, with all the pems and spacers and connector holes and vents in >>> place, and have it fabbed for less than buying an unfinished >>> "standard" chassis. >> >>Do you mean for the external case, or an internal subassembly? >> > > An entire rackmount enclosure, which is usually a folded/riveted pan, > a flat front panel, and a top cover with, say, captive 1/4 turn > fasteners. > > >>> Weird. >> >>I have found this in other areas. We had a common "passive" LCD (8 >>digit "triplexed") where we needed the polariser rotated 90 degrees >>from their normal type (don't ask). > > Please tell us all about it! Well OK then... We used to make boards with a soldered-in LCD that all sat behind a metal front panel, with a cutout for the LCD. We decided we wanted a "window" so we bought some nice "anti-reflection" plastic sheet stuff from Farnell. It worked by polarization - it cut down on reflections from the front of the LCD glass but not the back, so enhanced contrast. Or something. We didn't pay too much attention but did notice that if you rotated this anti-reflection window 90 degrees then the screen was totally black when viewed through the display. It was quite an interesting effect. So years went by and we shipped a few hundred like this, eventually we totally redesigned it with more modern electronics and a more "professional" construction, but we still shipped a lot of spare boards to support the old design. Then we started getting complaints that customers couldn't read the displays on the spare boards we were shipping. In fact they looked totally *black* - when viewed through the window - yet the old boards were fine... LCDs have polarizers too, and the manufacturer had rotated them all by 90 degrees, without telling anyone! In fact they told us that it is not controlled at all, it depends how the person loads the machine that cuts them up. To anyone else it would not matter, but we had fitted all our machines with circularly polarised windows! So we had to get them to do a "special", with the polarizer rotated back to its original direction. (And discovered that a "special" is much cheaper than a "standard"). -- John Devereux
From: krw on 20 Dec 2008 13:11 In article <494CB4B5.56CF071(a)hotmail.com>, rabbitsfriendsandrelations(a)hotmail.com says... > > > krw wrote: > > > rabbitsfriendsandrelations(a)hotmail.com says... > > > krw wrote: > > > > rabbitsfriendsandrelations(a)hotmail.com says... > > > > > John Fields wrote: > > > > > > Eeyore <rabbitsfriendsandrelations(a)hotmail.com> wrote: > > > > > > >Phil Allison wrote: > > > > > > >> "Adrian Tuddenham" > > > > > > >> > > > > > > > >> > A point not often appreciated is the possible heat gain when a heatsink > > > > > > >> > is operated in bright sunshine. A surface finish which is a poor > > > > > > >> > radiator/absorber of radiant heat will work better in those > > > > > > >> > circumstances. > > > > > > >> > > > > > > >> ** Only a complete dope would not find some way to shade the heatsink from > > > > > > >> direct sunlight on a hot day. > > > > > > > > > > > > > >There's no shortage of dopes. > > > > > > --- > > > > > > And you're the proof of the pudding. > > > > > > > > > > You're out of your depth. > > > > > > > > That's OK. You're out of your mind. > > > > > > How many of YOUR high power amplifiers are for sale in the shops and on ebay ? We've > > > made tens of thousands of them. > > > > I don't do "high power amplifiers" nor am I silly enough to use sil- > > pads on even high power processors (where we've made millions of > > them). You're out of your mind. > > As I said, I moved to bolting the collector direct to the heatsink when we went past a > certain power level. Because sil-pads *SUCK*, Dumb Donkey. > You don't even have a mind to be out of. You're *way* out of your league in this thread, Dumb Donkey. -- Keith
From: John Devereux on 20 Dec 2008 13:24 Eeyore <rabbitsfriendsandrelations(a)hotmail.com> writes: > John Devereux wrote: > >> "Michael A. Terrell" <mike.terrell(a)earthlink.net> writes: >> > Eeyore wrote: >> >> >> >> How many of YOUR high power amplifiers are for sale in the shops and on ebay ? >> >> We've made tens of thousands of them. >> > >> > >> > Ebay? That surely speaks volumes about quality. Along with the used >> > clothes, worn out tooling, and outright fraud. >> >> Yeah, all those old Tektronix scopes were clearly rubbish too. > > I sadly had to dispose of a couple of 545s. Just too big. My oldest one is a 7704A <http://www.barrytech.com/tektronix/tek7000/tek7704a.jpg> (not that actual one) I fancied getting one of the old valve based ones, thought it might make me like Jim Williams! <http://www.amazon.com/Analog-Circuit-Design-Personalities-Engineers/dp/0750696400> -- John Devereux
From: Michael A. Terrell on 20 Dec 2008 13:51 Eeyore wrote: > > John Devereux wrote: > > > "Michael A. Terrell" <mike.terrell(a)earthlink.net> writes: > > > John Devereux wrote: > > >> "Michael A. Terrell" <mike.terrell(a)earthlink.net> writes: > > >> > John Devereux wrote: > > >> >> > > >> >> Yeah, all those old Tektronix scopes were clearly rubbish too. > > >> > > > >> > A lot on Ebay are. They are dumped by cal labs becasue they aren't > > >> > worth fixing. > > >> > > >> They still fetch good prices because they were fine examples of > > >> quality engineering. (And I don't think you will find many others > > >> around here who would disagree). > > > > > > In most cases they need repaired & certified. A lot of parts are only > > > available from other scrapped units. A junkyard is full of cars that > > > may or may not have been worth buying. > > > > The point - if it was not obvious - is that an appearance many years > > later on ebay does not imply the original design is not of high > > quality. > > You are 100% correct. Terrell has simply lost his mind, sight , hearing probably and any other > useful faculty worth mentioning and only wants to spit bile. You are one to talk. You are second, only to Dimbulb. -- http://improve-usenet.org/index.html aioe.org, Goggle Groups, and Web TV users must request to be white listed, or I will not see your messages. If you have broadband, your ISP may have a NNTP news server included in your account: http://www.usenettools.net/ISP.htm There are two kinds of people on this earth: The crazy, and the insane. The first sign of insanity is denying that you're crazy.
From: Eeyore on 20 Dec 2008 14:13
"Michael A. Terrell" wrote: > Eeyore wrote: > > > > You are 100% correct. Terrell has simply lost his mind, sight , hearing probably and any > other > useful faculty worth mentioning and only wants to spit bile. > > You are one to talk. You are second, only to Dimbulb. I am in excellent health and have a bit of paper saying I have an IQ of 154. You ? Graham |