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oldschool@tubes.com: Aug 31 12:00PM -0400 The old 45 RPM (revolutions per minute) vinyl records were called 45's by everyone who had them.   If we were using a metric system at that time, would they still be called 45 rpm, or would there be some metric numbers used instead?   I was having this discussion with a few people and no one knew the answer..... (Personally, I think they would still be 45 rpm, but I could be wrong).

Taxed and Spent <nospamplease@nonospam.com>: Aug 31 10:07AM -0700 > I was having this discussion with a few people and no one knew the > answer..... > (Personally, I think they would still be 45 rpm, but I could be wrong).   I think they would be 4.5 drpm.

Cursitor Doom <curd@notformail.com>: Aug 31 05:50PM On Thu, 31 Aug 2017 12:00:46 -0400, oldschool wrote:   > by everyone who had them.   > If we were using a metric system at that time, would they still be > called 45 rpm, or would there be some metric numbers used instead?   No difference at all.           -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.

"pfjw@aol.com" <pfjw@aol.com>: Aug 31 10:55AM -0700 Revolutions per minute remain revolutions per minute in the old or new currency. Minutes and revolutions are neither metric nor SAE, nor Whitworth for that matter. all of them would count turns per time period the same.   There are also 45 rpm records of several diameters, to further confuse the issue for you.   But, each one revolves on the platter forty-five (45) turns per minute (60 seconds).   Note that in common use, RCA-base records were called 78s. Even though Edison discs were, most typically, 84s. LPs (33.3) were sometimes called "33s" but mostly LPs.   I suspect that those who were victims of your discussions were not so much uncertain of the answer as unable to formulate said answer in a way you could understand.   Peter Wieck Melrose Park, PA

Taxed and Spent <nospamplease@nonospam.com>: Aug 31 10:59AM -0700 > I suspect that those who were victims of your discussions were not so much uncertain of the answer as unable to formulate said answer in a way you could understand.   > Peter Wieck > Melrose Park, PA   I stand by my answer: 4.5 drpm. Surely you have heard of Decca records!   :)

oldschool@tubes.com: Aug 31 01:15PM -0400 On Thu, 31 Aug 2017 10:59:08 -0700, Taxed and Spent   >I stand by my answer: 4.5 drpm. Surely you have heard of Decca records!   >:)   What does the "d" stand for? Is it "D"ecca?

dplatt@coop.radagast.org (Dave Platt): Aug 31 11:30AM -0700 In article <oo9ih4$ct8$1@dont-email.me>,   >I stand by my answer: 4.5 drpm. Surely you have heard of Decca records!   Owww. May vile vinyl vengeance visit itself upon you. :-)

rickman <gnuarm@gmail.com>: Aug 31 02:33PM -0400 > I was having this discussion with a few people and no one knew the > answer..... > (Personally, I think they would still be 45 rpm, but I could be wrong).   0.75 rps of course! I think I would call them 3/4 rips for short.   --   Rick C   Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998

Adrian Caspersz <email@here.invalid>: Aug 31 07:38PM +0100 > I was having this discussion with a few people and no one knew the > answer..... > (Personally, I think they would still be 45 rpm, but I could be wrong).   0.75 revs per second if you want to be completely non-SI about it?   https://physics.nist.gov/cuu/Units/outside.html   -- Adrian C

Adrian Caspersz <email@here.invalid>: Aug 31 07:40PM +0100 On 31/08/17 19:38, Adrian Caspersz wrote:   > 0.75 revs per second if you want to be completely non-SI about it?   > https://physics.nist.gov/cuu/Units/outside.html   er, non-non-SI ...   -- Adrian C

rickman <gnuarm@gmail.com>: Aug 31 02:42PM -0400 Adrian Caspersz wrote on 8/31/2017 2:38 PM: >> (Personally, I think they would still be 45 rpm, but I could be wrong).   > 0.75 revs per second if you want to be completely non-SI about it?   > https://physics.nist.gov/cuu/Units/outside.html   Depending on your usage of the info it might be 0.75*(2pi) or   4.712388980385 radians per second.   --   Rick C   Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998

Robert Roland <fake@ddress.no>: Aug 31 08:59PM +0200 >If we were using a metric system at that time, would they still be >called 45 rpm, or would there be some metric numbers used instead?   The metric part of the world also measures time in oddball units. I think we are stuck with it. Switching to a new system would be essentially insurmountable.   In the SI unit system, however, the unit for angular velocity is radians per second. 45 RPM is a touch over 4.7 radians per second. -- RoRo

Mark Storkamp <mstorkamp@yahoo.com>: Aug 31 02:55PM -0500 In article <oo9fh3$17a$1@dont-email.me>, > > answer..... > > (Personally, I think they would still be 45 rpm, but I could be wrong).   > I think they would be 4.5 drpm.   The French for a time tried decimal time where there were 10 hours in a day and 100 minutes in an hour. So in decimal minutes, or dm, it would be 64.8 rpdm or 6.48 drpdm.

Trevor Wilson <trevor@SPAMBLOCKrageaudio.com.au>: Sep 01 06:28AM +1000 On 1/09/2017 4:59 AM, Robert Roland wrote:   >> If we were using a metric system at that time, would they still be >> called 45 rpm, or would there be some metric numbers used instead?   > The metric part of the world also measures time in oddball units.   **Huh? You mean 'seconds'? Oddball?   BTW: The "metric part of the world" is 95% of the world. A pitifully insignificant 5% holds out against the inevitable.     I > think we are stuck with it. Switching to a new system would be > essentially insurmountable.   **RPM?     > In the SI unit system, however, the unit for angular velocity is > radians per second. 45 RPM is a touch over 4.7 radians per second.   **Rotating media is so last century. The number of users is utterly insignificant. I am, however, one of them.     -- Trevor Wilson www.rageaudio.com.au

"Percival P. Cassidy" <Nobody@NotMyISP.net>: Aug 31 04:50PM -0400 On 08/31/2017 02:42 PM, rickman wrote:     >> https://physics.nist.gov/cuu/Units/outside.html   > Depending on your usage of the info it might be 0.75*(2pi) or   > 4.712388980385 radians per second.   Radians/sec. was the unit I assumed it would be, but I didn't bother with the calculation   Perce

"Percival P. Cassidy" <Nobody@NotMyISP.net>: Aug 31 04:52PM -0400 > But, each one revolves on the platter forty-five (45) turns per minute (60 seconds).   > Note that in common use, RCA-base records were called 78s. Even though Edison discs were, most typically, 84s. LPs (33.3) were sometimes called "33s" but mostly LPs.   > I suspect that those who were victims of your discussions were not so much uncertain of the answer as unable to formulate said answer in a way you could understand.   Many decades ago, my father bought at an auction a wind-up gramophone with a collection of records, some of which were old Columbia 80-rpm discs.   Perce

dplatt@coop.radagast.org (Dave Platt): Aug 31 02:48PM -0700 In article <f0rb02Fnk97U1@mid.individual.net>,   >> 4.712388980385 radians per second.   >Radians/sec. was the unit I assumed it would be, but I didn't bother >with the calculation   I prefer furlongs per fortnight (measured at the outer edge, of course).   Since records can vary in diameter, this would require having at least one reliable reference standard for the industry to work from. Like the classic metric standards for length and weight, it should be of a stable, noncorroding metal, kept in an inert atmosphere in either Paris or Greenwich.   Gives new meaning to the term "platinum record", doesn't it?

Look165 <look165@numericable.fr>: Sep 01 01:14AM +0200 Go and masturbate.

tabbypurr@gmail.com: Aug 31 05:52PM -0700 On Thursday, 31 August 2017 19:33:44 UTC+1, rickman wrote: > > answer..... > > (Personally, I think they would still be 45 rpm, but I could be wrong).   > 0.75 rps of course! I think I would call them 3/4 rips for short.   Nearly, the second being the standard unit of time. They would be 0.75Hz.     NT

rickman <gnuarm@gmail.com>: Aug 31 09:27PM -0400 Dave Platt wrote on 8/31/2017 5:48 PM: > stable, noncorroding metal, kept in an inert atmosphere in either > Paris or Greenwich.   > Gives new meaning to the term "platinum record", doesn't it?   lol   --   Rick C   Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998

rickman <gnuarm@gmail.com>: Aug 31 09:29PM -0400 Trevor Wilson wrote on 8/31/2017 4:28 PM:   > **Huh? You mean 'seconds'? Oddball?   > BTW: The "metric part of the world" is 95% of the world. A pitifully > insignificant 5% holds out against the inevitable.   You talkin' 'bout US?       --   Rick C   Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998

Ralph Mowery <rmowery28146@earthlink.net>: Aug 31 01:11PM -0400 In article <oo9b8b$hvt$1@dont-email.me>, gnuarm@gmail.com says...   > I've never seen polarized caps that weren't marked. I've never seen > polarized caps that relied solely on the reel orientation to indicate > polarity.     Here is a link to a px of some SMD capacitors. The two on the right have that little tit I mentioned. It could be mistaken by someone like me that has never seen one as just some excess solder when it was made.   https://drive.google.com/drive/folders/0B7wJcih38lRAMl9MRk1sdnA3ajA   There probably are not any that are not marked in some way. I was just guessing at the reel thing.   As mentioned it is a hobby now and upto a short while ago I had not messed with any of the SMD. There have been lots of advances and changes in the components over the years. Just more to learn. I still have trouble with the values of some components being packaged in a small package.   Just hope I am not sounding like some of the other older people on here with the SMDs.

rickman <gnuarm@gmail.com>: Aug 31 01:42PM -0400 Ralph Mowery wrote on 8/31/2017 1:11 PM: > have that little tit I mentioned. It could be mistaken by someone like > me that has never seen one as just some excess solder when it was made.   > https://drive.google.com/drive/folders/0B7wJcih38lRAMl9MRk1sdnA3ajA   Ok, these are un-encapsulated tantalum caps and that pin is a part of the device internal connections. They are the same part as the yellow ones to the left (and maybe the black ones too, but not the round ones which are electrolytic), but without the plastic coating to make them smaller. Yes, the point might look like excess solder, but if you use a part without looking at the data sheet you are screwing up.     > changes in the components over the years. Just more to learn. I still > have trouble with the values of some components being packaged in a > small package.   Trouble? You mean you have trouble accepting the small sizes?     > Just hope I am not sounding like some of the other older people on here > with the SMDs.   Only a little... ;) Wanting to learn new stuff is what is setting you apart. It is hard to go with new ideas when you've been doing the same thing for a long time, especially when the eyesight makes it hard. But it's not impossible. I have essential tremor but I still make stuff from time to time. When it's work I let an assembly house deal with it.   --   Rick C   Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998

Ralph Mowery <rmowery28146@earthlink.net>: Aug 31 04:31PM -0400 In article <oo9hia$9nf$1@dont-email.me>, gnuarm@gmail.com says... > > have trouble with the values of some components being packaged in a > > small package.   > Trouble? You mean you have trouble accepting the small sizes?   Not really trouble, but just have not worked with the SMD enough to learn all the small details. Like learning that they can make a capacitor of over 1 uF the size of fly poop and not big enough to have any markings on them.   The first computers I dealt with had the memory chips that would thake 8 chips to make about 1 K of memory, maybe not even that much. Just the memory board alone for 8 K of memory was larger than several of the smart phones now. Now they over 100 GB of memory in the space of one of those chips. I can accept them, just have not seen enough of them to know they are in use.   I just have to keep up with the times. Like the cars. I remember changing oil from 30 W to 20 W and back when the temperature changed from summer to winter, and change every 3000 miles, or was it less. Then came the 10W 40 types and no change was needed for summer to winter and 5000 or 7500 mile change.. Just bought a new car and the recommendation is 0 w 20 and only change at 10 K miles. They give 2 years free maintence. Going by the book, that is only 2 oil changes the way I drive. Nothing else to be done but look it over.

Jon Elson <jmelson@wustl.edu>: Aug 31 02:24PM -0500 Dave M wrote:   > Anyone have experience in accurately cutting 1/8" thick acrylic Plexiglas > (Perspex) for LED displays?   Real Plexiglas normally cannot be sheared. it can be scored with a special knife and snapped off like glass cutting. It can also be machined with a router or mill. Just be sure the cutter is super sharp and keep the tool moving fast. Cutting slowly leads to heat build up and melting. > filters. > Also thought about hot wire cutting. That's quite possible, relatively > safe (just have to keep fingers off the hot wire). I do NOT think you can hot wire-cut acrylic. It will make a LOT of fumes and cut very slow. Acrylic has a pretty high melting point.   > Also thought about cutting on a drill press or milling machine. Again, a > bit dangerous due to the small size of the work. Clamping would be > tricky. Just rectangles? Why would clamping be tricky? If making a lot, you clamp a sheet by the edges, and rout out the pieces, leaving a little space between parts.   My scheme, if really setting up to make a bunch, would be to set up a fence on the table saw and cut a bunch of strips the length of the Plexi sheets to match one of your dimensions. Then, stacking a bunch of these strips, cut the other dimension. That would make a lot of parts quickly.   If you need highly accurate dimensions, then the mill is the way to go.   Jon

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Ralph Mowery <rmowery28146@earthlink.net>: Aug 31 10:27AM -0400 In article <oo85si$sgh$1@dont-email.me>, gnuarm@gmail.com says...   > I think you just answered your question. If the caps have polarity markings > they are polarized. If they don't have polarity markings, how do you know > you have any installed correctly?   Someone sent a pix with several kinds of the SMD capacitors. A couple of them had a pointed tit on one end. I did not know that,so would have missed that as a polariaty mark. If I had just looked at the capacitor, I probably would have dismissed it as just a blob of material instead of a polarity mark.   Sometimes it helps to know all the small details of the components. I don't know, but guess that some could not have any marking and it could depend on how they are placed in the reel they come in.

rickman <gnuarm@gmail.com>: Aug 31 11:54AM -0400 Ralph Mowery wrote on 8/31/2017 10:27 AM: > missed that as a polariaty mark. If I had just looked at the capacitor, > I probably would have dismissed it as just a blob of material instead of > a polarity mark.   I don't know if that *is* a polarity mark. I'm not sure what you are describing, but I don't recall seeing any SMD polarized capacitors that don't have *clear* markings of polarity. Do you have an image or can you find a similar cap on the Internet?     > Sometimes it helps to know all the small details of the components. I > don't know, but guess that some could not have any marking and it could > depend on how they are placed in the reel they come in.   I've never seen polarized caps that weren't marked. I've never seen polarized caps that relied solely on the reel orientation to indicate polarity.   --   Rick C   Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998

Stephen Wolstenholme <steve@easynn.com>: Aug 31 01:00PM +0100 On Wed, 30 Aug 2017 17:57:06 -0500, "Dave M" <dgminala@mediacombb.net> wrote:   >Any suggestions as to a good, safe approach to cutting the plastic?   Repeatedly score it with a suitable blade and snap it along a hard strait edge. When I was using a lot of perspex I had a strait edge made with a steel rule glued to a wooden board. Occasionally I needed to use two boards clamped in a vice.   Steve   -- http://www.npsnn.com

Chris Jones <lugnut808@spam.yahoo.com>: Aug 31 10:24PM +1000 On 31/08/2017 08:57, Dave M wrote: > bit dangerous due to the small size of the work. Clamping would be tricky.   > Any suggestions as to a good, safe approach to cutting the plastic?   > Dave M   As others have said, use a CO2 laser. About 40 watts or higher should do the job. They cost from about $4000 upwards, and are so useful that many hobbyists and clubs have them. It leaves a nice smooth edge on acrylic. Acrylic is one of the materials that it can cut well and safely. (e.g. Don't ask them to cut PVC, it makes acidic fumes that attack the mechanism of the machine and poison the bystanders.)

gray_wolf <g_wolf@nospam.com>: Aug 31 07:35AM -0500 On 8/30/2017 5:57 PM, Dave M wrote:   > I've thought about using a table saw with a cabinet-grade finishing blade. > That's possible, but somewhat dangerous due to the small size of the > filters.   A triple chip for plastic would be your best bet.

Joseph Gwinn <joegwinn@comcast.net>: Aug 31 09:43AM -0400 On Aug 31, 2017, oldschool@tubes.com wrote > it's still hot and soft, but that did work in the end. (The soldering > iron tip was pretty much trash though, I ssaved it for future plexiglass > holes, but would never try to solder with it).   When drilling plastics like plexiglass, one does it flooded with tap water, to prevent overheating amd melting into a gooey mess. Do not use oil - this will crack most plastics.   Joe Gwinn

Neon John <no@never.com>: Aug 31 10:03AM -0400 On Wed, 30 Aug 2017 17:57:06 -0500, "Dave M" <dgminala@mediacombb.net> wrote:   >Anyone have experience in accurately cutting 1/8" thick acrylic Plexiglas >(Perspex) for LED displays?   Use the score-and-snap method. Purchase a scoring tool from any of the big box stores or many hardware stores. This tool has a backward pointing scoring point and cuts a 90 deg Vee.   Score the plastic along a straightedge to about 1/3 the thickness. That's about 3 passes with the scoring tool.   Position the plastic on a counter or bench with a sharp edge, locate the score over the edge. Place your palm on the plastic and firmly push down. The acrylic will cleanly snap. If you get a ragged break or a chunk of plastic remains on one end, you didn't score deeply enough.   John John DeArmond http://www.neon-john.com http://www.tnduction.com Tellico Plains, Occupied TN See website for email address

"Dave M" <dgminala@mediacombb.net>: Aug 31 09:44AM -0500 Jasen Betts wrote:   > send these guys 1:1 scale SVG with your outlines, they'll cut them > into a sheet.   > they seem to have a "first order free" deal going at the moment.     This looks promising. I'll look into it and see what the costs are (future projects). It's a great concept, sorta like sending Gerber files to a PCB house, and they make the board to my specs.   OK, thanks for all the suggestions. I just got a response from an Ebay seller, saying that if I buy a suitable panel of his Plexiglas, he will cut into pieces of my specifications at no charge!! Can't beat a deal like that. BTW, the seller's Ebay name is seefinestore, based in New York. Don't know if he gave me a one-time deal, or if he will do this for any order, but it solves my immediate problem.   Thanks for the pointer to ponoko, I'll keep it for reference for future projects. Dave M

"pfjw@aol.com" <pfjw@aol.com>: Aug 31 06:40AM -0700 http://www.dvhrc.com/kutztown.html   Can't believe this has been going on since 1992, and getting bigger with each event.   September 15/16, with dealer set-up on the 14th. As usual, I will be at the club table for the clinic, and running Radio Free Kutztown.   Camping is free, admission is free. Probably 200+ dealers in 35,000 s.f. under roof and about 1/3 again as much in the open. Look at the pictures.   Peter Wieck Melrose Park, PA

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"Dave M" <dgminala@mediacombb.net>: Aug 30 05:57PM -0500 Anyone have experience in accurately cutting 1/8" thick acrylic Plexiglas (Perspex) for LED displays?   I need to make filters for some panel meters of my own design, but am having trouble finding off-the-shelf bezels and filters of the sizes I need. Before everyone tells me that there are cheap Chinese panel meters available on the web, I already know about them. My meters are for a unique application and the available digital panel meters can't be modified to fill my needs. The display is the really unique part, and I need to make my own filters for the displays. I need 3 different sizes; 1.25" x 2.5". 2.75" x 5" and 4" x 5".   I've thought about using a table saw with a cabinet-grade finishing blade. That's possible, but somewhat dangerous due to the small size of the filters. Also thought about hot wire cutting. That's quite possible, relatively safe (just have to keep fingers off the hot wire). Might be hard to keep the wire taut enough to make straight cuts, and guiding the plastic through the wire or the wire through the plastic. Also thought about cutting on a drill press or milling machine. Again, a bit dangerous due to the small size of the work. Clamping would be tricky.   Any suggestions as to a good, safe approach to cutting the plastic?   Dave M

dplatt@coop.radagast.org (Dave Platt): Aug 30 04:32PM -0700 In article <sIWdnVPVfP1e3zrEnZ2dnUU7-IfNnZ2d@giganews.com>,   >>I've thought about using a table saw with a cabinet-grade finishing blade. >That's possible, but somewhat dangerous due to the small size of the >filters.   https://www.bobvila.com/articles/how-to-cut-plexiglass/#.WadJJnWGNo8   "For thicker sheets of plexiglass, cut with a power saw—be it a circular saw, saber saw, or table saw. (To cut anything but a straight line, opt for a jigsaw.) No matter which type of saw you choose for the task, it's critically important to use the right blade. There are special blades designed expressly for acrylic, but any metal-cutting blade with carbide tips can do the trick. Before committing to one blade or another, double-check that its teeth are evenly spaced, with no rake, and of uniform height and shape."   For the size you're talking about, I'd think that a table-type sabresaw or jigsaw (with a fence) would be what you'd want.   For a fancier approach - the MightyOhm geiger counter kit can be purchased with a two-piece acrylic case, the upper sheet of which has some custom cut-outs made for the tube and the batteries. Their web page says that it's "laser cut". Maker shops may have suitable laser-cutters for their members to use, and there are service companies which will laser-cut-to-size in your choise of acrylic types.

Randy Day <randy.day@sasktel.netx>: Aug 30 05:36PM -0600 In article <sIWdnVPVfP1e3zrEnZ2dnUU7-IfNnZ2d@giganews.com>, dgminala@mediacombb.net says... > Anyone have experience in accurately cutting 1/8" thick acrylic Plexiglas > (Perspex) for LED displays?   [snip]   Is there a makerspace near you with a laser cutter, or a laser cutting company?   Water jet cutting?

"Dave M" <dgminala@mediacombb.net>: Aug 30 06:55PM -0500 Dave Platt wrote: > laser-cutters for their members to use, and there are service > companies which will laser-cut-to-size in your choise of acrylic > types.   I've contacted four Ebay sellers of Plexiglas panels, asking if they can cut to my dimensions. Although they all advertise that they can cut to custom sizes, all but one of them say that they can't cut that small due to "liability insurance restrictions", whatever that might be. The other quoted an unbelievably high price for a small order of 25 pieces. That's why I'm looking to do it myself.   I looked at the Geiger Counter kit and didn't see any reference to any plexiglas except for a clear panel covering the front of the unit, clearly not what I'm after. At any rate, I'm not going to buy several $100 Geiger Counter kits for which I have no use just to get $15 worth of plastic.   Yes, the finishing blade that I mentioned is a zero-rake blade, so that't not a problem. Just concerned about my fingers when they get close to the blade spinning at 3200 RPM. I'm leaning toward building a hot wire cutter into a frame that will keep the wire taut enough to make a straight cut through the plastic. Maybe mount it alongside the fence on my tablesaw. That should keep everything nice & straight.   Thanks, Dave M

"Dave M" <dgminala@mediacombb.net>: Aug 30 07:30PM -0500 Randy Day wrote:   > Is there a makerspace near you with a laser cutter, > or a laser cutting company?   > Water jet cutting?   Don't know about a makerspace. Never heard of them. Have to see what Google churns up.   Dave M

krw@notreal.com: Aug 30 08:46PM -0400 On Wed, 30 Aug 2017 17:57:06 -0500, "Dave M" <dgminala@mediacombb.net> wrote:     >I've thought about using a table saw with a cabinet-grade finishing blade. >That's possible, but somewhat dangerous due to the small size of the >filters.   That should be no problem on a table saw. Make sure to use a zero clearance insert. Cut into the short-side sized strips with a fence than chop those up with a miter gauge with a stop. Perfectly safe.   >Also thought about cutting on a drill press or milling machine. Again, a >bit dangerous due to the small size of the work. Clamping would be tricky.   >Any suggestions as to a good, safe approach to cutting the plastic?   Your first thought should work just fine as long as you take reasonable care.

tabbypurr@gmail.com: Aug 30 05:53PM -0700 On Thursday, 31 August 2017 00:55:19 UTC+1, Dave M wrote: > > Dave M <dgminala@mediacombb.net> wrote: > >> Anyone have experience in accurately cutting 1/8" thick acrylic > >> Plexiglas (Perspex) for LED displays?   yes but not for LED displays.   > > evenly spaced, with no rake, and of uniform height and shape."   > > For the size you're talking about, I'd think that a table-type > > sabresaw or jigsaw (with a fence) would be what you'd want.   I would rule out any type of saw for a few reasons 1. Such a small piece is impossible to hold effectively unless you're using a low speed handsaw, which is very ill suited to acrylic 2. Power saw speed plus very slow feed are required, and there's no way you'll get good enough control with such a fiddly unsupported piece 3. Anything else will crack it 4. Your fingers will be at too much risk     > "liability insurance restrictions", whatever that might be. The other > quoted an unbelievably high price for a small order of 25 pieces. That's > why I'm looking to do it myself.   It's doable, but the options shrink heavily.   > nice & straight.   > Thanks, > Dave M   Hot wire would do it, and gravity tends to keep it cutting straight. You can sand the edges afterwards to get dimension precise. An easier option is to use an abrasive stone in a dremel, cutting/melting as close as you can to your scribed line, but never over it, then sand it.     NT

John Larkin <jjlarkin@highland_snip_technology.com>: Aug 30 05:56PM -0700 On Wed, 30 Aug 2017 17:57:06 -0500, "Dave M" <dgminala@mediacombb.net> wrote:   >Anyone have experience in accurately cutting 1/8" thick acrylic Plexiglas >(Perspex) for LED displays?   Polycarb is a bit easier to cut. Acrylic melts and gums up blades easier.     --   John Larkin Highland Technology, Inc picosecond timing precision measurement   jlarkin att highlandtechnology dott com http://www.highlandtechnology.com

Martin Riddle <martin_ridd@verizon.net>: Aug 30 09:26PM -0400 On Wed, 30 Aug 2017 17:57:06 -0500, "Dave M" <dgminala@mediacombb.net> wrote:   >bit dangerous due to the small size of the work. Clamping would be tricky.   >Any suggestions as to a good, safe approach to cutting the plastic?   >Dave M   I have scored and snapped Plexiglas. You would need to mount it firmly so that the corners don't break. A small fixture (plywood) to sandwich the piece should work fine.   Cheers

Bob Engelhardt <BobEngelhardt@comcast.net>: Aug 30 09:28PM -0400 I've had a lot of trouble cutting acrylic on a table saw, or drilling. The problem has been chipping on the back side. I haven't tried backing it with a piece of wood - that should help.   What does work very well for giving a nice edge is a router. Not very convenient for cutting into pieces, but nice for cutting shapes to a template, or for finishing edges that have been cut with too much chipping.

mhooker32@gmail.com: Aug 30 06:47PM -0700 On Wednesday, August 30, 2017 at 6:57:16 PM UTC-4, Dave M wrote: > bit dangerous due to the small size of the work. Clamping would be tricky.   > Any suggestions as to a good, safe approach to cutting the plastic?   > Dave M   at my job, we cut plexiglass( USA) on a sheet metal shear. makes a nice cut that requires little sanding to make smooth. 1/8 is thin. any tin shop would have shear that could cut that, even a manual one would work.

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Aug 30 06:50PM -0400 On 08/30/2017 06:57 PM, Dave M wrote: > bit dangerous due to the small size of the work. Clamping would be tricky.   > Any suggestions as to a good, safe approach to cutting the plastic?   > Dave M   Stack them in a vise and mill.   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

Joe Chisolm <jchisolm6@earthlink.net>: Aug 30 10:38PM -0500 On Wed, 30 Aug 2017 17:57:06 -0500, Dave M wrote:   > bit dangerous due to the small size of the work. Clamping would be tricky.   > Any suggestions as to a good, safe approach to cutting the plastic?   > Dave M   Variable speed dremel with a cutoff wheel will work.       -- Chisolm Republic of Texas

oldschool@tubes.com: Aug 31 12:32AM -0400 On Wed, 30 Aug 2017 17:57:06 -0500, "Dave M" <dgminala@mediacombb.net> wrote:   >bit dangerous due to the small size of the work. Clamping would be tricky.   >Any suggestions as to a good, safe approach to cutting the plastic?   >Dave M   When a hardware store cuts plexiglass for a storm door or window, they put the sheet in a glass cutting frame. That is nothing more than a rack with a straight edge and a lever to apply pressure against the part you want cut. Then they use a special cutter made for plexiglass, which is really just a sharp blade. They score it with that cutter from top to bottom. Then they use that lever to apply pressure and SNAP, they make a nice clean cut.   I was in a place where I had to cut some myself. I did not have that special cutter or a rack. I marked it with a sharpie. Then I took a straight piece of aluminum, laid it on my mark, and scored it with a utility knife with a new blade. Once it was scored, I placed the scored line along the edge of a board and applied pressure with my hand. That worked fine.   One thing I learned, never try to drill plexiglass. You will end up with small cracks around the hole. I once wanted to put some hinges onto plexiglass and learned the hard way about the cracks. Then I used a soldering iron and melted holes. It was kind of messy, sicne the melted plastic builds up around the hole and needs to be quickly removed while it's still hot and soft, but that did work in the end. (The soldering iron tip was pretty much trash though, I ssaved it for future plexiglass holes, but would never try to solder with it).

N_Cook <diverse@tcp.co.uk>: Aug 31 07:40AM +0100 On 30/08/2017 23:57, Dave M wrote: > bit dangerous due to the small size of the work. Clamping would be tricky.   > Any suggestions as to a good, safe approach to cutting the plastic?   > Dave M   I would use , don't know what they're called, miniture tenon saw from a craft shop for marketry I believe, blade only about 1 x 2 inches, but large handle, and teeth about the same as a hack-saw size and spacing

Tom Gardner <spamjunk@blueyonder.co.uk>: Aug 31 08:37AM +0100 On 30/08/17 23:57, Dave M wrote: > Also thought about cutting on a drill press or milling machine. Again, a > bit dangerous due to the small size of the work. Clamping would be tricky.   > Any suggestions as to a good, safe approach to cutting the plastic?   Have a look at laser cutting. Bonus: you can cut complex shapes as easily as simple shapes. Caution: not all materials can be cut like that.   Look for a local Hackspace or Makerspace, if you want to learn how to use laser cutters yourself.   Alternatively there are many commercial companies available. Usually you just send them the CAD file and they return the items by post, but obviously you could pick them up from a local company.

"Artemus" <bogus@invalid.org>: Aug 30 07:53PM -0700 "Dave M" <dgminala@mediacombb.net> wrote in message news:sIWdnVPVfP1e3zrEnZ2dnUU7-IfNnZ2d@giganews.com...   > Any suggestions as to a good, safe approach to cutting the plastic?   > Dave M >Make and use a small parts sled to hold the pieces and keep your fingers out of harms way. Do a search for "woodworking small parts sled" for an assortment of photos and plans. Use the tablesaw to just score the plastic. Don't cut all the way through. Snap on the score lines and file off any rough edges. A propane torch will polish the edges to a glass like finish. Practice on a scrap first as it's easy to burn the edge. Art

unk <me@privacy.net>: Aug 31 10:41AM On Wed, 30 Aug 2017 17:57:06 -0500, Dave M wrote:   > Anyone have experience in accurately cutting 1/8" thick acrylic > Plexiglas (Perspex) for LED displays?   Does it have to be perspex? 1/8" polycarbonate (Lexan) cuts with tinsnips, no cracks, nice enough edge if you are covering it with any frame; otherwise pass them a few times over a big file held in the vise.

"pfjw@aol.com" <pfjw@aol.com>: Aug 31 04:11AM -0700 Stuff that thin can be scored with a matt knife and broken on the score. With care, even on a curved score. For curved shapes, make a template in thick cardboard and cut along that. If you need to do this more than once, soak the curved edge in a very thin cyanoacrylate glue, then file it to the final shape. That will resist scoring by the blade.   Today, I have a Dremel Scroll-saw with a fine plastic-blade. Makes life easy. I tend to cut a bit proud of the final shape and use a very fine sanding disc to finish. It gives a nice edge and no flash.   Peter Wieck Melrose Park, PA

Jasen Betts <jasen@xnet.co.nz>: Aug 31 11:13AM > I've thought about using a table saw with a cabinet-grade finishing blade. > That's possible, but somewhat dangerous due to the small size of the > filters.   use a drop saw instead.   -- This email has not been checked by half-arsed antivirus software

Jasen Betts <jasen@xnet.co.nz>: Aug 31 11:27AM > "liability insurance restrictions", whatever that might be. The other > quoted an unbelievably high price for a small order of 25 pieces. That's > why I'm looking to do it myself.     https://www.ponoko.com/laser-cutting/acrylic   send these guys 1:1 scale SVG with your outlines, they'll cut them into a sheet.   they seem to have a "first order free" deal going at the moment.   -- This email has not been checked by half-arsed antivirus software

rickman <gnuarm@gmail.com>: Aug 31 01:17AM -0400 Ralph Mowery wrote on 8/29/2017 5:55 PM:   > Yes, the polarity is very important if the capacitor has one. I have > not installed any of thse backwards to see what happens as of yet. I > have seen the old aluminum and tantalum one blow over the years.   I think you just answered your question. If the caps have polarity markings they are polarized. If they don't have polarity markings, how do you know you have any installed correctly?     > I am not used to seeing capacitors ( other than large AC and speaker > crossover) much over 1 uF.   MLCCs (which are ceramic) can be found above 1 uF. I often use them at 10 uF and I know they are available at higher values. The product of capacitance and voltage determines the size, so in a given size the voltage will drop as the capacitance approaches the max value. There are also different material ceramic caps with widely different tolerances and voltage/temperature responses. X5R is a good general purpose type of ceramic cap.     > shop work,but good enough for hobby,and if it breaks, the replacement is > not that much.   > I am learning a lot about the capacitors with the help here.   While the idea of a cap is pretty simple, the realities can get pretty complex.   --   Rick C   Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998

rickman <gnuarm@gmail.com>: Aug 30 01:44PM -0400 Michael A. Terrell wrote on 8/29/2017 7:12 PM:   > Think again. You have a negative and a positive peak, not just a single > peak. You have to add them together. That is why the original DC cap was > 600V, not 300V.   You are very good at math, but not so good at electronics. You don't need to consider the peak to peak voltage because the cap doesn't see them both at the same time. It sees one peak, then it sees the other peak. The fact that they are opposite polarity doesn't mean you need to add them to consider the capacitor voltage rating.   --   Rick C   Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998

tabbypurr@gmail.com: Aug 30 05:41PM -0700 On Wednesday, 30 August 2017 00:12:17 UTC+1, Michael Terrell wrote:   > Think again. You have a negative and a positive peak, not just a > single peak. You have to add them together. That is why the original DC > cap was 600V, not 300V.   Sorry but that ain't so.     NT

rickman <gnuarm@gmail.com>: Aug 30 01:46PM -0400 Trevor Wilson wrote on 8/30/2017 1:36 AM: >> he's willing to go (unless he throws in a Super "Shammy" if you order now!!).   > **Dunno what I was thinking. I should have offered to pay him to take the > stuff.   Maybe we can offer to pay him to not post here?   --   Rick C   Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998

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"Michael A. Terrell" <mike.terrell@earthlink.net>: Aug 29 07:15PM -0400 Tim R wrote:   >> Best think to do is check with each manufacturer and pick by diameter not pound weight.   > Yes, that's what I'm trying to explain. That kastking is called braid but it's the modern stuff, not the old cheap line.   > It's okay for fishing but you absolutely don't want to put it in a radio at any strength or diameter. It's super slippery, hard to tie a knot that will hold, and it has no abrasion resistance. But it's diameter is tiny so fish don't see it, and it casts very well.   You also want to be close to the original diameter. If it is much larger, it can bind and wear out faster, or just jam on the main tuning shaft. If it is smaller, it won't have enough friction to work properly.     -- Never piss off an Engineer!   They don't get mad.   They don't get even.   They go for over unity! ;-)

Trevor Wilson <trevor@SPAMBLOCKrageaudio.com.au>: Aug 30 03:35PM +1000 On 29/08/2017 5:54 PM, rickman wrote: > from ebay without buying from the most expensive seller and then he gets > mad when people express frustration in trying to help him.   > What is wrong with this guy Oldschool?   **He is one of the most astonishingly stupid people I've run across.   -- Trevor Wilson www.rageaudio.com.au

Trevor Wilson <trevor@SPAMBLOCKrageaudio.com.au>: Aug 30 03:36PM +1000 On 28/08/2017 9:42 PM, John-Del wrote: >> addresses of people who are ham radio operators. Maybe they can provide >> some real help, since it's obvious I wont get it here.   > You should probably take Trevor's offer as "free" seems to be as low as he's willing to go (unless he throws in a Super "Shammy" if you order now!!).   **Dunno what I was thinking. I should have offered to pay him to take the stuff.   -- Trevor Wilson www.rageaudio.com.au

"Michael A. Terrell" <mike.terrell@earthlink.net>: Aug 29 07:12PM -0400 >> 2.828 is the peak to peak factor on a RMS sine wave. That is >> 1.414 volts peak, on each side of zero   > Erm... no. Firstly 275v ac is 389v dc peak, so a 389v dc rating. Secondly the 2 ratings are not comparable, even after conversion to dc. The 600v cap has no fusing and most likely no double layer safety feature, the 275v ac one has both.   Think again. You have a negative and a positive peak, not just a single peak. You have to add them together. That is why the original DC cap was 600V, not 300V.     -- Never piss off an Engineer!   They don't get mad.   They don't get even.   They go for over unity! ;-)

Ralph Mowery <rmowery28146@earthlink.net>: Aug 29 08:02PM -0400 In article <_oydnUQN6YdVaTjEnZ2dnUU7-cnNnZ2d@earthlink.com>, mike.terrell@earthlink.net says...   > Think again. You have a negative and a positive peak, not just a > single peak. You have to add them together. That is why the original DC > cap was 600V, not 300V.     While there is a positive and negative peak, the capacitor only charges to the peak and not p to p. The charge reverses at each half cycle.

tabbypurr@gmail.com: Aug 29 05:46PM -0700 On Wednesday, 30 August 2017 00:12:17 UTC+1, Michael Terrell wrote:   > Think again. You have a negative and a positive peak, not just a > single peak. You have to add them together. That is why the original DC > cap was 600V, not 300V.   275v ac = 389v peak, which can be withstood by a 389v rated capacitor. The reason they used 600v was to improve safety & reliability. However time showed that it wasn't good enough. X & Y caps are much better attempts to address the failure/safety issues.     NT

"Ian Field" <gangprobing.alien1@virginmedia.com>: Aug 29 10:23PM +0100 "Ralph Mowery" <rmowery28146@earthlink.net> wrote in message news:MPG.340e4bcbb44ddece989997@news.east.earthlink.net... > they are probably the same material, so the larger ones won't be > ploarized either. I did notice the voltage on them is only 10 volts > instead of 25 and 50 like the others.   The lower voltage ratings are probably tantalum, polarity is *VERY* important.   Don't be fooled by large capacitance values - I've seen a brochure for MLCC capacitors up to 180uF.   SMD tantalum caps are usually encapsulated (after a fashion) and usually have markings.   SMD ceramics are rarely encapsulated and rarely have any markings. Sometimes I've encountered MELF round glass encapsulated MLCC caps on high end equipment.

Ralph Mowery <rmowery28146@earthlink.net>: Aug 29 05:55PM -0400 In article <kXkpB.728842$YV4.539839@fx18.am4>, gangprobing.alien1 @virginmedia.com says...   > SMD ceramics are rarely encapsulated and rarely have any markings. Sometimes > I've encountered MELF round glass encapsulated MLCC caps on high end > equipment.   Yes, the polarity is very important if the capacitor has one. I have not installed any of thse backwards to see what happens as of yet. I have seen the old aluminum and tantalum one blow over the years.   I am not used to seeing capacitors ( other than large AC and speaker crossover) much over 1 uF.   I can see why they don't mark most of the SMD, just no room but with micro printing there may be a way but it would cost. Even buying them from Digikey and Mouser they are very inexpensive compaired to the old point to point components.   As mentioned, been working with components for over 50 years,but just started with the SMD in the last year. Could not justify the items it took to do that for just a hobby. Now they have came down a lot. Like the China hot air rework station for about $ 60 and a $ 200 microscope. The hot air station is probably no where near good enough for regular shop work,but good enough for hobby,and if it breaks, the replacement is not that much.   I am learning a lot about the capacitors with the help here.

tabbypurr@gmail.com: Aug 29 05:44PM -0700 On Tuesday, 29 August 2017 22:55:42 UTC+1, Ralph Mowery wrote: > shop work,but good enough for hobby,and if it breaks, the replacement is > not that much.   > I am learning a lot about the capacitors with the help here.   I've seen SMDs where one end is a bit pointed to indicate polarity.   If there's really nothing to indicate polarity it's most likely nonpolar. Hook one up & see, not that hard.     NT

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Ralph Mowery <rmowery28146@earthlink.net>: Aug 24 06:07PM -0400 In article <f08qkkFllqgU2@mid.individual.net>, trevor@SPAMBLOCKrageaudio.com.au says... > whole spool of the stuff. Stop nickel and diming the thing. Either buy > the right stuff to do the job or accept my offer. BTW: My dial cord is > made in Taiwan, not China.   He is really tight. This might even be the same cord.   $ 5.62 for 10 meters including that high price of about a buck and a half for shipping.   http://www.ebay.com/itm/DIAL-CORD-0-8-mm-synthetic-cord-10-metres-to- suit-radios/222592615826?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao% 3D2%26asc%3D41376%26meid%3Dca3db13179c64681aa64f94629564bb7%26pid% 3D100005%26rk%3D5%26rkt%3D6%26sd%3D391772693645 &_trksid=p2047675.c100005.m1851   eBay item number:22259261582

John-Del <ohger1s@gmail.com>: Aug 29 06:52AM -0700 On Tuesday, August 29, 2017 at 8:42:33 AM UTC-4, Tim R wrote:   > > Best think to do is check with each manufacturer and pick by diameter not pound weight.   > Yes, that's what I'm trying to explain. That kastking is called braid but it's the modern stuff, not the old cheap line.   > It's okay for fishing but you absolutely don't want to put it in a radio at any strength or diameter. It's super slippery, hard to tie a knot that will hold, and it has no abrasion resistance. But it's diameter is tiny so fish don't see it, and it casts very well.       So the "Tuf-LINE" would be the better choice? Taking a second look at the Kastking link I see it's braided but not listed as Dacron. Maybe that's the determiner. Again, I didn't want to do oldfart's homework for him..

"pfjw@aol.com" <pfjw@aol.com>: Aug 29 07:48AM -0700 I happen to like this stuff. Takes knots very well, a bit fat (more contact area), does not abrade, and stretch is minimal.   https://images-na.ssl-images-amazon.com/images/I/51002pXn%2ByL._SL500_.jpg   But, would I suggest it to someone for other than generic purposes, or flying kits? Not hardly. Would I have purchased it without seeing a sample first? Not hardly. Do I own a vernier caliper? Yes, I do. Along with various other measuring sticks.   Peter Wieck Melrose Park, PA

Rheilly Phoull <rheilly@bigslong.com>: Aug 26 09:06AM +0800 > and each time it has started normally. > Cheers, > Eric   I would guess that the connector was moving a little each start until it finally came out. The last few times it would make up with the previous start. Generally contactors either buzz - vibrate or close, no in between.

etpm@whidbey.com: Aug 25 04:52PM -0700 It looks like the problem wasn't caps after all. Or the time delay relay. While poking around inside the electrics enclosure and putting number labels on wires so that I could remove the contactor I found a female spade connector just hanging behind the contactor coil spade terminal. It's really hard to see the coil connections because it is buried pretty deep and a lot of wires are in the way. So I pushed the spade connector back on and it just slipped on real easy. Too easy. I pulled it back off and wormed the wire through the others and could see that the female connector was open too much. Maybe years of vibration loosened it. So I closed the connector some with pliers and when I tried pushing it on again it was quite tight. After putting the rest of the wiring back in order I tried starting the RPC (Rotary Phase Converter) and it started normally, which is essentially instantly. Now I have another question. Since the spade connector was loose could this have caused a high resistance connection which in turn caused the contactor to barely pull in which then made for another high resistance connection between the starting caps and the motor? I know that at least some types of relays have a higher pull in current than the holding current. So that once they pull in less current is required to keep the contacts closed. In other words a curve of the current required is shaped like a hill, with the holding current past the crest a little. But I think that maybe contactors for motors may work differently because they have so much more travel in the solenoid after the spring loaded contacts first make contact, unlike "regular" low current relays. And since the current required to pull in the contactor remains the same even a slight decrease in current would cause the contactor to drop out. And maybe a low current situation could cause the contacts to make only a light, high resistance, contact. Anyway, thanks for reading all these posts and thanks for the advice given. While writing this post I have started the RPC 6 times and each time it has started normally. Cheers, Eric

dplatt@coop.radagast.org (Dave Platt): Aug 25 01:08PM -0700 >750Gb and no remaining unpartitioned space.   >A 2Tb drive works just fine - I'd even settle for that from the 3Tb >one..........   I suspect that what you're running into is the 2.2-terabyte limit in the standard PC Master Boot Record. This would correspond to 32 bits worth of sectors (4 hexabillion) at 512 bytes each.   Probably, when your partition table is being built, the software you're using is trying to read the hard drive size via the PC BIOS, and the sector count is wrapping around past 4 billion. The program ends up with (3 terabytes - 2.2 terabytes) worth of sectors, and so you only get 750 GB.   I'm not an expert in the PC BIOS, but I suspect that the "read drive sector count" call returns a 32-bit result, and the BIOS isn't smart enough to clip (rather than wrap) at 2.2 terabytes. If that's the case, no matter what program you use, you'll hit the same behavior.   There's probably a fix, although it won't be trivial. What you would need to do is let the software partition the drive. If you want more than one partition, delete the single 750-gig existing one and create the smaller ones you want at first, and then create a final partition which uses up the remainder of the 750 GB space.   Then go in with a sector-level disk editing program, and edit the partition table by hand. Take a look at   https://en.wikipedia.org/wiki/Master_boot_record   You'd want to edit the "number of sectors in partition" value at offset 12 (0x0C) for the last (or only) partition and set it to "0xFFFFFFFF" (or slightly less than that) and store this entry. This would expand that partition to 2.2 terabytes.   Save the MBR, reboot, and I think you'd find that you have more space available.   HOWEVER: depending on how your PC accesses the drive, you could find that Bad Things happen when it tries to write beyond the 2.2-terabyte boundary - reads and writes might wrap around to the beginning of the disk. For that reason, it would probably be safest to limit the total size of the partitions you create to slightly less than 2.2 terabytes, so that all of the subsequent I/O operations are compatible with a 32-bit sector-offset API.

dplatt@coop.radagast.org (Dave Platt): Aug 25 02:34PM -0700 In article <2A%nB.616461$JP7.13240@fx09.am4>, >Pretty sure something nasty would happen if I tried for more than 2.2Gb >partition - but I can't even get that.   >I was thinking more along the lines of 2x 1.5Tb partitions.   That _may_ be workable, but you're probably going to have to do more math, and become more familiar with the PC Master Boot Record and how to hack it.   Setting up the MBR to work in LBA (logical block address) mode, rather than C/H/S, would probably make things easier.   Again, it's going to depend a lot on your PC and its device drivers. If it's capable of accessing the drive in LBA48 mode (with a 48-bit logical block address) you may get away with it. If not, you may be stuck with 2.2 terabytes at most.

"Ian Field" <gangprobing.alien1@virginmedia.com>: Aug 25 07:09PM +0100 What's the best I can do?   All the partition managers tried so far, offer a single partition just under 750Gb and no remaining unpartitioned space.   A 2Tb drive works just fine - I'd even settle for that from the 3Tb one..........   Thanks for any help.

"Ian Field" <gangprobing.alien1@virginmedia.com>: Aug 25 09:15PM +0100 "Dave Platt" <dplatt@coop.radagast.org> wrote in message news:4nc67e-hp.ln1@coop.radagast.org... > size of the partitions you create to slightly less than 2.2 terabytes, > so that all of the subsequent I/O operations are compatible with a > 32-bit sector-offset API.   Pretty sure something nasty would happen if I tried for more than 2.2Gb partition - but I can't even get that.   I was thinking more along the lines of 2x 1.5Tb partitions.

Mike Tomlinson <mike@jasper.org.uk>: Aug 25 11:32PM +0100 En el artículo <WJZnB.462838$a64.200548@fx16.am4>, Ian Field <gangprobi   >A 2Tb drive works just fine - I'd even settle for that from the 3Tb >one..........   >Thanks for any help.   This is the wrong group for a start.   3TB requires a GPT partition table, which XP32 doesn't support.   Either use a 2TB drive with MBR partition table (that XP does support), or upgrade to a later version of Windows (7 onwards supports GPT).   -- (\_/) (='.'=) "Between two evils, I always pick (")_(") the one I never tried before." - Mae West

etpm@whidbey.com: Aug 28 12:59PM -0700 >Best test is to buy a cap that is close to the required value to use as a test.   >If it works, buy the right cap and be happy you had an inexpensive repair of an expensive machine.   >m   As it turns out it was a loose connection buried deep in the electrics box. One of the spade connectors on the coil in the contactor was loose. NOT easy to find. Even though the wiring in the phase converter is neat there are a lot of wires and many of these wires hide the contactor coil connections. Fortunately not the ten caps connected in parallel that are used for starting the thing were at fault. Eric

etpm@whidbey.com: Aug 25 11:34AM -0700 Well, this morning the phase converter won't start at all. There is a button that can be pressed that energizes the contactor that connects the 10 starting caps to the motor. This button bypasses the time delay relay that energizes the contactor. Pressing the button has no effect at all, the motor just hums. I don't know yet if the contactor is pulling in or not because I cannot see into the electrics enclosure while throwing the breaker that turns on the phase converter. Even though I can press the bypass button while throwing the breaker I cannot see the contactor. I'll have to get another set of eyes to look inside while I turn the converter on. Getting on subject, I have a DVM that has a capacitance measuring function. Measuring half a dozen known good oil filled caps the readings on the meter match very closely, within one MFD, the value printed on the caps. If I measure the caps in the phase converter and they measure close to the value printed on the case does this mean the caps are probably good? Is there another test I can perform with the meter? And since there are 10 starting caps connected in parallel could just one or two bad caps cause the starting problem? Thanks, Eric

etpm@whidbey.com: Aug 25 03:15PM -0700 >> Eric   >AIUI you could have cap(s) leaking or a faulty switch contacts. Soldering a wire to short the starting switch could tell you which. Obviously don't power the motor for >5 seconds like that.   >NT Soldering a wire across switch contacts won't work easily because the switch is a contactor. What I'm gonna do is get someone to look at the contactor when I turn on the breaker to see if it pulling in. If it is pulling in then I'll remove it and check the contacts. Then replace them if need be. If the contactor doesn't pull in then I'll need to find out if the coil is bad or if it isn't getting power. I will still need to check the caps if the contactor is working properly. Eric

etpm@whidbey.com: Aug 25 11:03AM -0700 <SNIP>   >There is an electronic device that's got its innards potted. It senses >the starting current and when the current drops to the set level it >drops out the contactor that connects the starting caps. <SNIP>   >spinning the rotor, albiet slowly? >Thanks, >Eric     Whoops! I was wrong about the starting device. I just assumed it was some sort of potential relay like I had seen in other motors. It's a bad thing to assume sometimes. In reality the starting device in an adjustable delay solid state relay. The on time, once energized, is from .25 to 5 seconds. It resets when power is removed. Supossedly good for 100,00,000 operations. But the original timer failed after only approximately 600 operations. Eric

etpm@whidbey.com: Aug 25 09:26AM -0700 On Fri, 25 Aug 2017 09:25:37 +0800, Rheilly Phoull >> Eric   >After 15 years I reckon I would just get another cap and see if that >fixed it. What sort of device takes out the cap, centifugal ? There is an electronic device that's got its innards potted. It senses the starting current and when the current drops to the set level it drops out the contactor that connects the starting caps. There 10 starting caps connected in parallel so I don't think it's such a good idea to replace them all just in case that's the problem. They are all stuck in place with some pretty good double sided foam tape so removing them would be a hassle too. I cannot see how many mfd the caps are rated for but I can see on one cap that they are made for a phase converter. I just remembered that years ago the device mentioned above failed. When I tried to start the converter it would just hum. There is a button inside that I can press that bypasses the starting device and energizes the contactor coil. When the starting device failed the first time I was told by the phase converter maker to press this button and see if it starts OK. It did which is how I diagnosed the problem. The company that made the converter has gone out of business so I can't call them for advice. But I'm gonna try the button thing again and if it starts fine then I guess I know the problem. What I don't understand is why the converter sometimes starts to spin up slowly and at other times just sits there and hums loudly. And then starts just fine on the next attempt. Could it be that when it starts to spin up slowly that the rotor was in just the right position that the balancing caps in the converter provide enough phase shift to start spinning the rotor, albiet slowly? Thanks, Eric

etpm@whidbey.com: Aug 25 12:07PM -0700 >spot? It's hard for me to see how a cap would need two tries >to do it's job right.   >George H. Yeah, I'm starting to think the contactor contacts are the problem. Just so you know, a Rotary Phase Converter (RPC) is just a 3 phase AC induction motor that is run from single phase power. Once the motor is spinning it generates power in the third winding, AKA leg, that would normally be connected to a three phase supply. They are started the way many single phase motors are started. A typical type of single phase induction motor has a starting winding that is powered only while the motor is starting. This winding is shifted in phase about 90 degrees from the main winding. Both physically as well as electrically. The electrical phase shifting can be done using resistance, capacitance, or a combination of the two. There are other schemes as well but the capacitance method is common on motors that need lots of torque when starting, like a motor on an air compressor. A simple RPC can be made using just a 3 phase motor. A rope can be wrapped around the motor shaft and then pulled fast to get the motor spinning. Once it is spinning single phase power is supplied and the motor will spin up to operating speed if the shaft was spinning fast enough from the rope pull. Another motor can be used to spin up the RPC motor as well. This motor is then either disconnected mechanically or just turned off once the RPC motor is running. Capacitors can also be used to supply phase shifted current just like a single phase motor. Again, once the motor is up to speed the starting capacitance is disconnected. Even though the RPCs described above will supply 3 phase power the generated power will not be perfectly in phase with the other two phases. And depending on the load the phase shift will vary as will the voltage. So more sophisticated RPCs will use capacitors across the windings to balance the power so that the phases are very close to 120 degrees apart and the voltage in the generated leg is close to the voltage supplied to the motor by the single phase line. That's my simple explanation of RPCs. Eric

etpm@whidbey.com: Aug 24 03:31PM -0700 I run my machine shop off af a rotary phase converter. It has starting caps that are switched out of circuit after the motor is started. Lately the device sometimes has a hard time starting. I switch it on and the motor may not come up to speed practically instantly, the way it is supposed to. If this happens I turn off the breaker, wait a minute, and then try again. It always starts fine on the second attempt. Except this morning it took three tries for the thing to start. The motor did actually spin up some this morning on the first try but it was really slow starting so I shut the breaker off. I suspect starting caps but wonder why the second attempt always worked until today. And then today it started fine on the third attempt. The phase converter has been started almost daily for at least fifteen years using the same breaker in the main breaker panel. I thought that maybe the breaker might be making a bad contact on one leg of the single phase 250 volt input. Or maybe a contactor inside the converter is not making good contact. Or maybe, and I think most likely, the starting cap(s) is(are) the problem. I just wonder why, if the thing doesn't start spinning right away on the first try it does on the second or third. This weekend I'll have time to look inside the phase converter and I would like to know if there is a way to diagnose the starting caps. The contactor contacts I know how to check. And I could buy a new breaker. But I would like to not just buy stuff until the thing works properly. Advice? Thanks, Eric

Ralph Mowery <rmowery28146@earthlink.net>: Aug 24 07:32PM -0400 In article <5ujupclqvbqv63fcgrqa0smbbib74g9p5k@4ax.com>, etpm@whidbey.com says... > Advice? > Thanks, > Eric   There are many ways to check the capacitors. You can find capacitor "meters" and testers from about $ 15 up. You may be able to find a shop that works on air conditioners and take the capacitors to them and have them checked. Usually they will have a voltmeter device that just hooks across the capacitor. Takes longer to find the meter than to check the capacitor.

Rheilly Phoull <rheilly@bigslong.com>: Aug 25 09:25AM +0800 > Advice? > Thanks, > Eric   After 15 years I reckon I would just get another cap and see if that fixed it. What sort of device takes out the cap, centifugal ?

rickman <gnuarm@gmail.com>: Aug 24 03:46PM -0400 Dave Platt wrote on 8/24/2017 2:32 PM: > in some equipment you're refurbishing, I'd suggest going right to a > suitable "Y" cap. The additional cost is modest and the labor to > install is the same.   Ok, so there is a failure mode where the cap won't draw enough current to blow the fuse, but can locally heat up enough to smoke and burn. Isn't that true for other parts in the device?   What is the purpose of this cap anyway? I assume noise filtering. Wouldn't that be just as effective on the secondary of the transformer?   --   Rick C   Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998

rickman <gnuarm@gmail.com>: Aug 24 02:37PM -0400 >> across the power line shorts? If you use a fuse any concern about a fire is >> eliminated. Then why would you need the X cap?   > Y is for shock risk, X is for fire risk only.   Ok, I stand corrected. But the question remains. Fuse and X cap is like wearing a belt and suspenders.   --   Rick C   Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998

dplatt@coop.radagast.org (Dave Platt): Aug 24 11:32AM -0700 >problem as in a shock hazard. Why would there be a shock hazard if a cap >across the power line shorts? If you use a fuse any concern about a fire is >eliminated. Then why would you need the X cap?   You can't count on a fuse to eliminate all of the risk of a fire.   Some types of cap can fail with a "near short circuit" - they get leaky enough to start drawing a good fraction of an ampere, but aren't a dead-short. Imagine what happens if such a cap is "protected" by a 1-ampere fuse, but is drawing 100 mA at 120 volts... that's more than 10 watts, heating up the capacitor. If the cap doesn't either short itself well enough to blow the fuse, or go "open", it can definitely heat up enough to smoke and burn.   I've seen this happen... a non-X/Y-rated film cap was used "across the line", and it overheated and nearly started a fire.   "X" and "Y" caps are intended to be at least somewhat self-healing... if they develop a pinhole and start to short, the localized heating burns away the metallized film in the area of the short, and it opens. If I recall correctly they're also required to use an insulating resin which is at least somewhat flame-resistant.   If you're going to the trouble of replacing an across-the-line cap in some equipment you're refurbishing, I'd suggest going right to a suitable "Y" cap. The additional cost is modest and the labor to install is the same.

tabbypurr@gmail.com: Aug 29 06:22AM -0700 On Tuesday, 29 August 2017 11:02:29 UTC+1, Michael Terrell wrote: > to a 777VDC capacitor.   > 2.828 is the peak to peak factor on a RMS sine wave. That is 1.414 > volts peak, on each side of zero   Erm... no. Firstly 275v ac is 389v dc peak, so a 389v dc rating. Secondly the 2 ratings are not comparable, even after conversion to dc. The 600v cap has no fusing and most likely no double layer safety feature, the 275v ac one has both.     NT

Dimitrij Klingbeil <nospam@no-address.com>: Aug 25 12:45AM +0200 >> is like wearing a belt and suspenders.   > You need belt & suspenders since both fail. Just don't put the pics > online. :)   Besides, using an X2 capacitor does call for an additional means of protection. Capacitors rated for being connected across the line "X" come in different sub-categories: "X1" and "X2".   "X1" capacitors are rated for a 4 kV transient overvoltage and they are often found where no other means of protection (fuse) is installed in the equipment "upstream" of the capacitor (that is directly across the power line).   "X2" capacitors are only rated for a 2.5 kV transient overvoltage and the circuits they are installed in need to be fused as an additional means of protection (additional besides the dielectric in the cap).   Both X1 (rated to 4 kV pulse) and X2 (rated to 2.5 kV pulse), when used within their specifications and unless their safety certifications are fake, tend to be better protected than "plain" 600 V type capacitors.   The voltage ratings indicate the maximum AC line voltage that the X or Y capacitors may safely be connected to (not their peak pulse ratings).   So, it's correct (and would be required in a repair) to replace the old 600 V capacitor with a 250 V safety rated "X" capacitor (assuming the nominal mains voltage in your country is not higher than 250 V), but if the capacitor is an "X2" (rather than "X1") type, the device also needs to be fused "upstream" (on the mains side) of the X capacitor.   Regards Dimitrij

Cursitor Doom <curd@notformail.com>: Aug 22 11:03PM On Mon, 21 Aug 2017 16:12:18 -0700, tabbypurr wrote:   > Abuse does not remedy the absence of fact or logic.   Actually for Antifa, its acolytes and apologists, it most assuredly does!       -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.

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