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  1. hevans1944

    DC to AC converter

    @kellys_eye is saying you may not need it. Most medical electronics equipment runs internally on DC. One reason to build such equipment to operate from low-voltage AC is isolation (via a transformer) from the power line. Since only a step-down transformer is needed to provide an AC voltage that...
  2. hevans1944

    Connecting electrical devices into DC grid - polarity

    I have discovered a remarkable feature of this forum! If you don't care to read the posts of someone, for whatever reason(s), just right-click on their icon to bring up a page with their info. Near the top of the new page there are links to Report, Ignore, and Follow. Click on Ignore and...
  3. hevans1944

    Connecting electrical devices into DC grid - polarity

    @Maris: It appears that you have some misconceptions about how electricity works. Please do your homework and exercise due diligence and research before posting questions in this technical forum. I would recommend that you visit this Google results page for starters.
  4. hevans1944

    PSpice Bipolar Junction Transistors Modeling

    @insyspower: Is there some reason you are cross-posting the identically same message here as well as on stackexchange.com? On the stackexchange website, user laptop2d responded to your message with the comment that you failed to ask a question. You have not yet responded on stackexchange. The...
  5. hevans1944

    Positively charged "holes"?

    ... or flip a light switch or watch a television program or listen the the radio... all these being sufficiently advanced technology indistinguishable from magic and, unlike real magic, requiring no skill to practice.
  6. hevans1944

    Positively charged "holes"?

    I started writing something for you, @darren adcock, but I got pulled away to replace a hardside waterbed heater. Then I read @BobK's and @Ratch's excellent replies. Wow! Very concise and to the point. You DO need to understand some quantum mechanics and the math that goes with it if you want...
  7. hevans1944

    Meaning of balance current: 36/72+-5mA for Battery spec?

    Please post a link to the spec sheet.
  8. hevans1944

    After the Transformer Help

    @dorke directed you to an Instructables page that describes how to build an electrolysis etcher, which is quite different in operation and concept from spark engraving. Much safer, too, in my not-so-humble opinion. However, with that said, spark engraving is much simpler and should be much...
  9. hevans1944

    What is this?

    If I were in your shoes, I would de-solder the inductor and confirm there is continuity between the two wire leads. After you acquire a decent multimeter of course. Most likely the inductor is not damaged, and the fault lies elsewhere, perhaps in a switching transistor. You can then put the...
  10. hevans1944

    Difference between maxload and clamping voltage?

    If your power line ever surges above the clamping voltage, the internal "clamping device" will rapidly lower it's resistance from virtually an "open circuit" across the power line to virtually a "short circuit" across the power line. Depending on the magnitude and duration of the surge, this...
  11. hevans1944

    What is this?

    Why do you want to replace it? There doesn't appear to be anything wrong with it. Did you try to measure the resistance between the two wire leads? It should be quite small, effectively the resistance of the wire used to wind the inductor. To identify the "exact parameters" requires that you...
  12. hevans1944

    What is this?

    It's a ferrite-core inductor covered in blue shrink tubing.
  13. hevans1944

    Why is so expensive to fabricate custom IC

    You would think, with U.S. Government support, i.e., a research and development contract, it would be easy to develop a new semiconductor device. In my former job at UES, Inc. we did just that at the request of the Defense Threat Reduction Agency (the military subsidiary of Homeland Security)...
  14. hevans1944

    Car battery jumpstart gadgets

    Aww... does this mean a moderator is gonna close this thread now?
  15. hevans1944

    Why is so expensive to fabricate custom IC

    For the layman, it's called "economy of scale" as pioneered by Henry Ford in the early part of the 20th Century. It always costs more to make the first of anything. After that, if you can invoke mass production methods of manufacture, the cost per unit manufactured plummets as the fixed costs...
  16. hevans1944

    understanding discrete circuits

    Use it or lose it. I believe most high school graduates here in the United States, immediately after graduation, remember little to nothing of what they studied immediately before graduation... and much less than that ten years after graduation. And I am being generous, assuming they actually...
  17. hevans1944

    Can anyone ID this transformer?

    Amazing find! It is clear from the low-voltage secondary windings that this high-quality transformer was intended to power vacuum tubes in its original incarnation. The 5R4-GYB full-wave duo-diode rectifier was the usual choice for DC rectification, but it required 5 VAC for its filaments...
  18. hevans1944

    Can anyone ID this transformer?

    Steve, do you even have a boat to use these transformers as anchors with?:D
  19. hevans1944

    Car battery jumpstart gadgets

    Yes, but we did get a new member involved in our discussion. There are sooo many people that show up here as just "hit and run" posters, looking for a "cheap and dirty fix" to whatever their problem is. At first I thought @portyforty might be one (he does say he subscribes to, or visits...
  20. hevans1944

    Concurrent operation in real time embedded systems (C)

    Excellent choices for the embedded processing tasks you described. As you are probably aware by now, VxWorks is a Real Time Operating System or RTOS, and of course C or C++ is becoming the language of choice for complex embedded systems. It sounds like your application needs pre-emptive...
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