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  1. hevans1944

    Pulsed signal

    And, please, do not try to start a private conversation with me. This forum is conducted in English, and English is the ONLY language I speak, read and write. And why did you upload redacted images from what appears to be a patent application?
  2. hevans1944

    Pulsed signal

    It is possible to modulate a pulsed microwave transmitter to transmit the voice... cell phones basically do this using time division multiplexing of digitized audio "packets." Support infrastructure then allows the cell phone to call (connect) to one or more other cell phones, almost anywhere in...
  3. hevans1944

    CO2 laser tube lifespan - time used vs age of tube?

    AFAIK, there are only two gas lasers available for sale to the general public: CO2 and HeNe. Both contain "laser gas" mixtures that include helium, probably for some esoteric quantum mechanical reason. Helium cannot be contained by any known substances because it is inert and can "slip past" the...
  4. hevans1944

    Stage Line 500W amp repair project

    Back in the day (mid 20th century) there were two pieces of audio test equipment that were very useful: an audio signal injector and an audio signal tracer. You can build either one of these for your own personal use using inexpensive parts. A 555 timer chip makes a nice audio signal injector...
  5. hevans1944

    Stage Line 500W amp repair project

    IMHO, both instruments are not only useful, but also essential for any serious electronics hobby work involving audio. Almost everyone gets their "feet wet" with audio circuits when beginning to learn electronics. Even if it's just a "crystal radio set" with a ceramic ear-piece, pulling in a...
  6. hevans1944

    Rest in Peace, Kris

    Aw, geez guys... I still have the parts we tried to use on @TenderTendon's Flashlight Project, all except for that damned fancy LED controller. You know, the one that changed modes when the current through it was briefly interrupted... I had intended to purchase one just to see how brief of an...
  7. hevans1944

    Convert Hoverboard to RC remote control

    Hmm. This thread is more than a year old, and the OP (@Peterino) only stuck around for four days, last seen lurking here on April 23, 2019 after joining this forum on April 19, 2019. That looks like a drive-by poster to me, one who moves on when they don't get the "quick solution" they need or...
  8. hevans1944

    Need some help finding direction for a new project

    Hmmm. I wonder what $5000 per bin buys these days? That sort of cost reminds me of the 1960s. This is a DIY site you are posting on, so why not try a few experiments to see if you can produce acceptable results and get the cost down to, say, $50 per bin? Strain gauges are inexpensive (in many...
  9. hevans1944

    Need some help finding direction for a new project

    An alternative, and usual, method to determine the amount of silo content is to weigh the grain silo. Ideally, this would be accomplished with load cells inserted under the supporting legs during silo construction, but clearly this accommodation was not made before the silos were installed. All...
  10. hevans1944

    Crystal clock and USB operation

    @Rajinder: Visit this page for information on how to implement a USB 2.0 interface. PICs might have been suitable for the original USB 1.0 standard (1.5 Mbps low-speed and 12 Mbps high-speed), but any PIC is waaay too slow for USB 2, much less USB 3, data transfer rates. You need a USB...
  11. hevans1944

    Far-field antenna polarization...

    What?! No digression into circular polarization?
  12. hevans1944

    Welding Problem: SPOT WELDERS (AMPS, WATTS, VOLTS)

    It is also important that the "welding" electrode be made of pure, OFHC (oxygen-free, high-conductivity) copper that conducts electricity readily and absorbs heat. You do not want the welding electrode to become part of the weld! And, as @Minder stated, adequate pressure must be maintained...
  13. hevans1944

    Welding Problem: SPOT WELDERS (AMPS, WATTS, VOLTS)

    Hello, @powerspy1010. Welding is not a skill that you can learn by reading about it, or even by viewing any number of videos. It requires a LOT of hand-eye coordination and a LOT of hands-on practice doing actual welding to become proficient. Unless you are a robot. Robots excel at repetitive...
  14. hevans1944

    Analog frequency meter

    Pretty spiffy IC you linked to, @WHONOES, although the spec sheet does say the frequency-to-voltage conversion (in which the OP is interested) takes longer than the voltage-to-frequency conversions, but the accuracy is impressive either way. Something "new-to-me" I should learn to play with...
  15. hevans1944

    Analog frequency meter

    @colum: Jeff, does your location of Midhudson mean Mid-Hudson, this area of New York State? Is your avatar a photo from a model railroad, HO gauge perhaps? Just curious. BTW, I like the old resonant vane frequency meters, but modern electronics makes it pretty easy to get a wider frequency...
  16. hevans1944

    COVID-19

    We know so little about the novel corona virus responsible for the COVID19 pandemic... what organs in the body does it infect? How long does it persist after antibodies are created to repel the invasion? Does getting infected provide any sort of future immunity to survivors? If an effective...
  17. hevans1944

    I cant measure voltage on 100 picofarad capacitors on multimeter

    @Martaine2005: Sure, go ahead and use it. Put it into practice and you will either become wise or seriously injured or dead. So far, I've been lucky and have acquired more wise than I deserve and only minor (non-serious) educational injuries.:D Live and learn. Or not.
  18. hevans1944

    I cant measure voltage on 100 picofarad capacitors on multimeter

    RE: Gigaohm resistors. The few that I have encountered, and successfully used as feedback resistors in electrometer circuits using op-amps with field-effect transistor (FET) input stages, were encased in glass envelopes. The glass envelopes are presumably either back-filled with dry nitrogen gas...
  19. hevans1944

    I cant measure voltage on 100 picofarad capacitors on multimeter

    Electrometers have a high enough input impedance to show the voltage discharge from a 100 picofarad capacitor, but why bother since (1) you probably won't be able to get your hands on one and (2) it sounds like you don't know enough electronics theory to appreciate what you would be trying to...
  20. hevans1944

    Where to find a rectifier that meets these requirments?

    @Voltcat: Clearly you have no idea what you are doing, much less what you are asking. I suggest you consult with someone who does this sort of thing and is licensed and insured before you either electrocute yourself or cause an electrical fire you won't have any idea how to extinguish...
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