Amclaussen

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Amclaussen

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  • 06.30.2017
  • Happy 150th Canada: The Companies
  • Not very important, but for the record add "Sombra Labs" in Ottawa, manufacturers of probably the finest ever 72 MHz model airplane Radio Control receivers... (now displaced by 2.4 GHz spread spectrum technology).
  • 08.16.2017
  • Whipping a cheap LED PSU into usable shape
  • On "Chinese quality". A model airplane store owner went to Hong-Kong looking for low prices. They showed him a large 3 X 3 ft display with TEN, yes 10 engines with 10 different prices for (almost) the same model engine, a 0.40 CI. He was puzzled by so many prices for seemingly the same engine. They gave him a succinct explanation: Top engine $125 USD, top quality ball bearings, run tested at factory, best surface finish, nicest anodized color on cylinder head. 2nd: $105, same but not run tested. 3rd: $95, same as before but less polished finish. 4th: $80, back plate is plastic, not metal. 5th: $70, "natural color, not anodized head, "std quality" ball bearings. 6th: bronze bushing instead of ball bearings, but nicely colored anodized head, different color from top quality engine. 7th: same but no anodizing… Perhaps lower priced ones are rejects or poor running ones! Chinese were not lying, nor incapable of producing very good quality products. The problem is other: It lies on the BUYER or IMPORTER trying to re-sell the mediocre quality levels to rise earnings. I have found many products from (supposedly) "American" brands, with quality issues. Even when the computer I'm writing on is 95% made with Chinese components, assembled in a Chinese factory by Chinese workers, it works OK. Most products can be made in China with good quality, EXCEPT for some things like precision bearings, precision measuring devices and the like. Saddest thing is that previously highly regarded "American" brands, now are Chinese enterprises that "bought" the American name, like my recently bought carpentry Router, a 2 1/2 HP variable speed from "Milwaukee". Bearings got noisy after less than two hours of moderate and careful use. "Soft-start" feature is more a delayed-action switch than a proper one. Does it work? Yes, but I will be guessing when will it start to develop play in the bearings or fail to vary the speed smoothly. Amclaussen
  • 08.16.2017
  • Whipping a cheap LED PSU into usable shape
  • If the rectifier is overheating, trying to "heat-sinking" it to the electrical box is not a good idea, a better one would be to replace the rectifier with a larger current capacity one. Plastic encapsulated rectifiers have poor heat conduction from die to case, and I know no heat sink for cylindrical rectifiers that could allow for an aluminum heat sink that is electrically insulated but heat conducting.
  • 09.06.2017
  • Beware the TO-220
  • The thinner tab is a no-no. When building high powered amplifiers back in the 70's, we preferred the old TO-3 because thanks to its TWO screws, it could be installed VERY FIRMLY to the heat sink, while the TO-220s were only partly in contact with their heat sinks because of a lack of flatness, and the fact that the single screw always deform the tab sufficiently to reduce the physical contact and thus impairing the heat transfer. And I don't care whatever the damn manufacturer says about "the same dissipation" ! Amclaussen.
  • 05.26.2017
  • Microsoft’s hardware support burden
  • Another example of how Microsoft stinks! I would be happy if Mr Bill Gates would be a little less cynical (as He pretends to be a "Phylantropist") and actually did something to cure the never ending problems of its company creations.
  • 08.03.2017
  • Dead meters expose battery terminal design issues
  • Probably 99% of the battery contacts are made from nickel plated flexible metal, as it is cheap enouh and it is considered "good enough", which is debatable. When wetted by the Potassium Hydroxide of the so called "Dry" cells, the terminal plating will suffer a tremendous corrosion rate, that will attack and pit the surface, rendering it's surface non-conductive. Even my HP-41CV calculator with gold plated flexible circuit battery teminals got dissolved by the alkaline electrolyte. Most plastics used in electronic devices will withstand the alkaline attack, but I know no metal that can withstand that kind of attack. We need a good metalurgist urgently!
  • 08.03.2017
  • Dead meters expose battery terminal design issues
  • Happy to see an engineer using Cramolin products that I have long recommended. My pair of small bottles (akin to nail polish bottles) have served me well for 29 years; labeled as "Cramolin Red Contact Cleaner and Deoxidizer” and “Cramolin Blue, Contact Preservative”, were sold by Monster Cable at Hi-Fi stores to clean contacts of Moving coil Phono cartrs in turntables, are so concentrated that a very small drop is enough, old articles recommended dissolving cleaner with liquid Freon (used to clean tape recorder heads) or Isopropanol (not as effective) to treat contacts or inject into noisy audio pots, VERY effective! On DMMs, I had little money to buy them. My first one was a Keithley hand held, failed miserably in less than a year of careful use. Was so expensive to fix that I left it at the service shop, where they had 30-40 of the same, all damaged... a really bad design! Then I got an inexpensive ($129) but versatile one at (YES, believe me) Radio-Shack in ’95, that is still accurate. It has an RS-232 output and can measure capacitance, frequency, logic and transistor measurements. Later in 2001, I bought a second one, again at another Radio Shack store at the unveliebable discounted price of $29.95!. Both were custom made for RS by METEX of Korea, and have proved to be reliable, durable and versatile, with a tremendous performance/price ratio. Sometimes you are just lucky, I don't know, but those two DMMs are two of my best purchases. In regards to repairing heavily corroded battery terminals, my old Hewlett-Packard HP-41CV calculator suffered TERRIBLE corrosion thanks to size "N" alkaline cells leaking courtesy of Duracell... The gold plated flexible circuit that serves as the battery terminals was actually dissolved more than just corroded. Gold plating did nothing to stop the electrolyte from taking it away. So I cut some thin copper sheet, tinned it with silver bearing solder, and adhered it to the calculator to repair the contacts.
  • 08.03.2017
  • Dead meters expose battery terminal design issues
  • Not so. Author is right in saying that alkaline "Dry" cells are NOT so dry, and will leak sooner or later. And it is NOT acid, but KOH, or Potassium Hydroxide, which is highly alkaline and thus corrosive. A better design would place the cells OUTSIDE the interior, so that there is a barrier placed between the cells and the rest of the circuit, as the article suggests. In my probably more than 50 years of using battery powered devices, I've suffered the effects of quite a few batt leaks. While quality of the cell is SOMEWHAT related to the absence of leaks, ALL brands will leak sooner or later. The only remedy I've found in some devices (like my two METEX DMMs) is to place the 9V cell inside a small polyethylene bag, and seal it with some silicone plus tying the bag where the connector leads go to the board; but for AA or similar cells that need to touch the terminals, I've no remedy yet.
  • 10.20.2011
  • Simple reverse-polarity-protection circuit has no voltage drop
  • I keep seeing relay coils being "clamped" with a simple diode to "remove" the spike... It appears that the simple diode is NOT the best protection. When looking at installing some relays into the cooling fan circuit in one of my cars, that happens to have a computer controlling the fuel injection and ignition, which is a delicate device hard to find and replace, I ran across a pair of notes written by TYCO, which explains in detail the pros and cons of the simple diode. One is titled: "The application of relay coil suppression with DC relays" document 13C3311 Printed U.S.A. IH/11-98. The other is titled "Coil Suppression Can Reduce Relay Life", document 13C3264 Printed U.S.A. IH/12-00. Both show the pitfalls and disadvantages of using a simple diode when using relays. It apperars that using a simple diode or single resistor is not the best way, and they suggest to use a combination of a diode with a Zener, to provide a better system.