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  1. hevans1944

    Comparator circuit analysis

    You are so full of nonsense. Diodes do not store either power or energy, except incidentally as a result of a minuscule charge stored on the capacitance of the diode junction when it is reverse biased. The only requirement for electricity to conduct (between two points in space) is a voltage...
  2. hevans1944

    wiring diagram does not match...

    @roughshawd apparently knows NOTHING about threads in this forum... how he responds to them and how he creates them seem to be just random postings without ANY continuity. To understand what he is talking about in this particular instance, you should visit at least three other posts he has made...
  3. hevans1944

    Comparator circuit analysis

    With negative feedback, you would basically be changing the comparator to an operational amplifier that is trying to drive a digital output instead of producing an output that is proportional to the difference in input voltage. How this would affect an LED that is driven by the digital output is...
  4. hevans1944

    Using a Mosfet to limit current to a high power Cree LED, Can't go higher than 400mAh??

    Pay close attention to what @Harald Kapp said in his post #4 above. You MUST be aware of your voltage budget! The voltage drops across the mosfet and the LED versus the battery supply voltage are VERY important considerations. A mosfet usually does not have a sufficiently large Rds(on) to limit...
  5. hevans1944

    Shortage in 3 terminals of mosfet

    The most likely cause is too much current in the mosfets, which will melt the silicon die inside the package and short everything inside together. Why would you want to simulate this effect on a breadboard? Destroying components tells you nothing, other than you have successfully destroyed the...
  6. hevans1944

    Hurricane Ian

    Thanks to everyone for your concern! Wife and I stayed-in-place instead of evacuating. Daughter in Sarasota and her husband are also okay, but I don't know if they evacuated. Our power was off for more than a week, but we had a gasoline-fueled 120 vac motor-generator to run our...
  7. hevans1944

    Circuit Sealant question

    When the only tool you have is a hammer, everything looks like a nail. If it's sticky and can be squeezed from a tube to harden in air into a rubbery-like substance, why not try it? Conformal coatings for PCBs were invented to increase survivability of the circuits they encapsulated, while...
  8. hevans1944

    Circuit Sealant question

    They are both room-temperature vulcanizing (RTV) rubber sealants that use acetic acid and oxygen in the air to perform the chemical conversion from a liquid-in-the-tube to a solid filler for high temperature caulking applications. The 76R has a 600F temperature rating and is red in color. The...
  9. hevans1944

    Can't find a PCB designer to hire for cool position. Is PCB design completely ignored in schools?

    I came across this old thread while looking for something else. It has some interesting links to books on PCB design. The thread also mentions a company that will design PCBs and manufacture them for you. I would give that company a phone call to try to find out where they obtain their PCB...
  10. hevans1944

    Can't find a PCB designer to hire for cool position. Is PCB design completely ignored in schools?

    @JohnRog: I, perhaps mistakenly, believe that most tech startups are under-funded and always strapped for cash, and that most will "burn through" whatever venture capital they were able to scrounge before selling a single product or service at a net profit. Having an initial core of clever...
  11. hevans1944

    Circuit selector

    That would be the LEAST of your potential problems... switching transients. You want to build a precision resistance calibrator that "dials in" and digitally displays resistance from one ohm to 1.9996x10^8 ohms? Good luck with that! I used to work as a technician in an electronics laboratory...
  12. hevans1944

    Can't find a PCB designer to hire for cool position. Is PCB design completely ignored in schools?

    Graduates of what? High school? Tech school? Two-year associates degree? Four-year baccalaureate degree? Some sort of PCB designer apprentice program? Maybe your company is looking in the wrong places. PCB layout is VERY specific to the type of circuitry and components the PCB supports. You...
  13. hevans1944

    what mosfet to use for an induction heater

    As before mentioned, this is the ELECTRONICS HOMEWORK HELP forum. Specific solutions to questions are verboten here! You are welcome to start a NEW thread in a DIFFERENT forum, but please do some research first. Find out how commercial induction heaters are built, their power requirements, and...
  14. hevans1944

    Bench power supply upgrade

    When my two boys and two girls were of the "right" ages to appreciate it, I began putting together a small HO layout. This would have been in the 1970s IIRC. Not a single one of them showed any interest in model railroading, much to my dismay, as I had an entire basement in which to build it...
  15. hevans1944

    Bench power supply upgrade

    Hmmm. I HATE getting old and forgetting how to do simple arithmetic. Five years seems like eternity here in Paradise. And I do sometimes read old threads, posted below threads like this one under the banner Similar threads. Don't often respond with a comment though, unless I forget to look at...
  16. hevans1944

    Bench power supply upgrade

    Ooops! I really HATE getting older and forgetting how to do simple math. March 2017 was three months after we moved into our house in South Venice, FL. That's when my pacemaker/defibrillator started shocking me a
  17. hevans1944

    Bench power supply upgrade

    No, I don't think I missed the point. As I said, ya pays yer money and ya makes yer choices. I prefer not to waste my valuable time trying to use components of unknown origin or quality. It makes troubleshooting much more difficult if you cannot trust that ALL the parts function the way they...
  18. hevans1944

    Bench power supply upgrade

    Too bad, since you purchased from China, that you have no idea what those 30 "devices" really are. Finding out "fer sure" would cost more... much more... than what you would have spent purchasing from a North American distributor the original lot of 10. But, hey, ya pays yer money and ya makes...
  19. hevans1944

    Help

    Never-mind!
  20. hevans1944

    New Format

    Thanks for "preserving" text and text . This may be intrinsic to BB code, though, and having to type the brackets is a PITA. Please add the "special symbols" back ASAP! I DO get by using Microsoft Character Map, but I agree with @Alec_t that the "old way" was better.
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