- Calibrated dial knob repair - 2 Updates
- WD-40 to clean electric contacts? - 5 Updates
- What differentiates good audio xmfrs from bad ones? - 7 Updates
| Jeff Liebermann <jeffl@cruzio.com>: Jan 22 10:54PM -0800 >However, grinding out that center will be tricky and time consuming, >since the new knob needs to be centered very precisely. This recently posted video might give you some ideas on what can be done: Cloning Vintage Knobs <https://www.youtube.com/watch?v=aNBHtlhlHF4> (10:45) I'm really impressed with his results. The list of materials in the video description section. If you want to go cheap, try Automotive Bondo and some mold release (or just some grease). Drivel: The Kidney stones are finally gone after six weeks and three laser lithotripsy surgeries. Not much pain and no complexications. I win. -- 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 |
| John-Del <ohger1s@gmail.com>: Jan 23 07:59AM -0800 On Wednesday, January 23, 2019 at 1:54:34 AM UTC-5, Jeff Liebermann wrote: > laser lithotripsy surgeries. Not much pain and no complexications. I > win. > -- Wow, sorry to hear you were afflicted with those bastards. I've had them several times and had one lithotripsy as did my wife (we're fertile I guess). I passed a 6mm stone about three months ago. Glad you're feeling better; drink more water and don't drink tea! |
| John Robertson <spam@flippers.com>: Jan 22 10:43AM -0800 >>> Find me one of those CAS numbers that is not a 100% volatile compound. >> How hot do you have to get it for this to happen? > How do you mean? Volatile at normal (room) temperatures. You may test this for yourself using a paper-towel. Anywhere from a few minutes to a few hours, depending on immediate conditions. I would think that spraying it on a clear sheet of glass would show up any residue better than paper towel... > Of course it takes longer in cool weather and so forth. > Peter Wieck > Melrose Park, PA John :-#)# |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Jan 22 12:33PM -0800 On Tuesday, January 22, 2019 at 1:43:49 PM UTC-5, John Robertson wrote: > I would think that spraying it on a clear sheet of glass would show up > any residue better than paper towel... Yes, and no. There are at least six (6) fractions in WD-40. The most persistent of which is a dewaxed light mineral spirit. That will take the longest to evaporate. A paper towel has the virtue of wicking all the fractions, thereby speeding the process. 64742-65-0 is the CAS number. And, if followed, it is named "Adriatic Spindle Oil". Trace it further, it is a non-staining, non-gumming material used for high-speed spindle lubrication. Trace it further, and where I have used it directly in my past, it is used in testing turbine seals at very high speed (10,000 - 50,000 rpm). That material would be the clear quill (100% single-fraction, undiluted). The material is injected constantly into the seal, and not recirculated. If none passed the seal, the seal passed (pun intended). The seal face is graphite, and self-lubricating, the spindle oil being a "visible air", air being used for static testing. As it is thinner than any turbine oil, it is very good for dynamic testing. In any case, we kept the containers sealed tightly as the stuff would evaporate otherwise, and was not at all cheap in the quantities used. Peter Wieck Melrose Park, PA |
| dplatt@coop.radagast.org (Dave Platt): Jan 22 04:51PM -0800 In article <a08e4efa-735a-4141-8d6a-505307d0ef91@googlegroups.com>, pfjw@aol.com <peterwieck33@gmail.com> wrote: X-Newsreader: trn 4.0-test77 (Sep 1, 2010) >evaporate. A paper towel has the virtue of wicking all the fractions, thereby speeding the process. >64742-65-0 is the CAS number. And, if followed, it is named >"Adriatic Spindle Oil". For what it's worth, I was curious about the "LVP aliphatic hydrocarbon" fraction (since it's a "low vapor pressure" material). This CAS (64742-47-8) turns out to have a vapor pressure of a couple of mm of mercury, and a volatility of 0.18 relative to butyl acetate. According to another site, water has a relative volatility of 0.3 on this scale, mineral spirits 0.1. So, this fraction of WD-40 evaporates faster than mineral spirits but slower than water. Hence, "volatile", but not highly volatile (naptha is 1.4, acetone is 5.6). For 64742-65-0, there seem to be a number of differently-named products which fall into this category. For most of them the MSDS says that the evaporation rate is "unavailable" or "n/a". The only actual number I found is for a product which contains more than 90% of this oil, and it lists the relative evaporation rate as <.01. So, volatile in principle, but pretty slowly - less than a tenth the rate of mineral spirits, less than 3% that of water. In practice I'd guess that this means "hours to days" rather than "minutes". Maybe about like lamp-oil kerosene? Whether any of these fractions contain some small amount of long-chain residuals that will hang around for weeks or months... I do not know. Due to the fact that these CAS numbers often cover a fairly broad range of products, and due to the fact that petroleum distillation usually doesn't produce anything like a chemically-pure product, one would probably have to test an individual batch of WD-40 to know for certain how it would behave under various conditions of evaporation. |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Jan 23 05:19AM -0800 On Tuesday, January 22, 2019 at 7:51:54 PM UTC-5, Dave Platt wrote: > would probably have to test an individual batch of WD-40 to know for > certain how it would behave under various conditions of evaporation. >Snippage< All pretty much true - but understanding the mechanics of evaporation does help. Aliphatic Hydrocarbon 64742-47-8 45%-50% Petroleum Base Oil <25% 64742-58-1 64742-53-6 64742-56-9 64742-65-0 NOTE: Five (5) Fractions making that <25%. And these are chain molecules, not ring molecule. Makes a difference. LVP Aliphatic Hydrocarbon 64742-47-8 12%-18% Surfactant Proprietary <2% Non-Hazardous Ingredients Mixture <10% Now the science: We have a solution of high and low volatility materials. For simplicity, lets stick with a simple solution of two miscible hydrocarbons, one LVP, one as volatile as say - V&PM Naptha. 1. The Naptha in your solution will evaporate at a constant rate. 2. The evaporation rate of the LVP will vary depending on the concentration of the mixture, but will always be higher than the evaporation rate of pure LVP, causing the Naptha/LVP mixture to evaporate faster. 3. The Naptha concentration will decrease with time, and there will always be a solution of pure LVP as the Naptha will completely evaporate first. Now, consider WD40 is a mixture of many compounds, and although more complicated a system than just two compounds, as a system, it is (and will remain) 100% volatile in a relatively shorter period of time than any one compound in the system. If the highest concentration also happens to be the most volatile fraction, that will materially affect overall evaporation speed. The general branch of science on this is called "Mixed Solvent Evaporation". Peter Wieck Melrose Park, PA |
| Cursitor Doom <curd@notformail.com>: Jan 23 03:19PM > The general branch of science on this is called "Mixed Solvent > Evaporation". I think this is why proprietary release agents stink when compared to home brew mixtures of thin oils and volatile solvents. Always make a fresh batch just prior to use. Makes all the difference. -- 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. |
| makolber@yahoo.com: Jan 22 09:39AM -0800 On Thursday, January 17, 2019 at 4:19:56 PM UTC-5, Phil Allison wrote: > The source impedance of a pentode or beam tube output stage is pretty high, triodes are somewhat better. > Only those amplifiers with large NFB ratios avoid the issue. > ..... Phil yep good point... so it is very possible for a tube amp to have a bit less transformer saturation distortion when loaded compared to unloaded. i.e. the distortion can go DOWN when loaded. m |
| Look165 <look165@numericable.fr>: Jan 22 07:13PM +0100 NO ! Saturation is a value coming from the magnetic core, yes. But H (magnetic strength) is directly proportional to the current, not to the voltage, at constant frequency. The load is very important. This leeds the core to the satruration point if too high. A free transformer (without load) rarely comes to saturation. Eddy's current (we call it Foucault's current in France) are proportional to I^^2, like copper losses. |
| Phil Allison <pallison49@gmail.com>: Jan 22 01:06PM -0800 Look165 wrote: > Saturation is a value coming from the magnetic core, yes. > But H (magnetic strength) is directly proportional to the current, not > to the voltage, at constant frequency. ** WRONG !!! The applied AC voltage and frequency are what matter. > The load is very important. > This leeds the core to the satruration point if too high. ** TOTAL BOLLOCKS !!! > A free transformer (without load) rarely comes to saturation. ** Try using an unloaded 120V supply transformer on 240V and see what happens. Others here have it right cos they know that they are talking about - you don't. Piss off you bloody idiot. .... Phil |
| Fox's Mercantile <jdangus@att.net>: Jan 22 03:43PM -0600 Or, you know, you COULD just look this shit up and learn how it works. <https://www.ieee.li/pdf/introduction_to_power_electronics/chapter_12.pdf> -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| makolber@yahoo.com: Jan 22 01:57PM -0800 it is about current, the so called magnetizing current that flows even with no load. the additional current that flows in the primary when the secondary is loaded IS CANCELED by the current in the secondary. So it is all about the current that flows only due to the primary inductance and not due to the load current. Yours is a common mis-conception. I'm glad to help you learn. m On Tuesday, January 22, 2019 at 1:13:17 PM UTC-5, Look165 wrote: |
| whit3rd <whit3rd@gmail.com>: Jan 22 02:49PM -0800 On Tuesday, January 22, 2019 at 10:13:17 AM UTC-8, Look165 wrote: > Saturation is a value coming from the magnetic core, yes. > But H (magnetic strength) is directly proportional to the current... > A free transformer (without load) rarely comes to saturation. NO, that's exactly backwards: a 'free' transformer with negligible secondary current DOES near-saturate. The primary current and secondary current are in the opposite direction, so load (secondary) current CANCELS the magnetization caused by the drive (primary) current. A lot of secondary current (high load current) removes the risk of saturation. |
| Phil Allison <pallison49@gmail.com>: Jan 22 03:22PM -0800 whit3rd wrote: > the magnetization caused by the drive (primary) current. > A lot of secondary current (high load current) removes the > risk of saturation. ** While adding load current does not directly alter the magnetising current in the primary, it does reduce the effective AC supply voltage seen by the primary. This is due simply to the resistance of the primary winding - current flow produces a voltage drop which must be subtracted from the external supply voltage to accurately model what is going on. Eg, say the primary current due to load is 1 amp and the winding has 5 ohms resistance - then the effective voltage is 5 volts LESS than the AC supply. .... Phil .... Phil |
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