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  1. hevans1944

    Help

    Not to "jump the shark" too far, but does anyone here know how to make a really cheap CO2 detector?
  2. hevans1944

    Help

    Watch the "modern" version of "War of the Worlds" with Tom Cruise. The "fog horn" sound effects produced by the aliens is awesome. You might be able to reproduce the same effect with a few loudspeakers and a kilowatt or so of intermittent audio power, all driven by a "loop" recorder that will...
  3. hevans1944

    New Format

    Nope. I am using Windows 11 on a Dell Inspiron laptop and its missing a "like" button here too. This was a terrible "upgrade" in my not so humble opinion.
  4. hevans1944

    Buying a Digital Oscilloscope.

    @Steamysteve: I bought a Hantek DSO5202P from Circuit Specialists in Tempe, AZ, USA for less than US$300.00 a few years ago. At current exchange rates, this would be close to ₤250, but be aware that there is currently rampant inflation of the US dollar. So, who knows what it sells for today...
  5. hevans1944

    absolute noob trying to start

    What I meant was, I don't know what the state-of-the-art is in BMS today. Clearly, not even Elon Musk could build a Tesla (or any other practical EV) using hundreds (if not thousands) of individual cells without battery management technology appropriate to the battery chemistry. I am pretty sure...
  6. hevans1944

    absolute noob trying to start

    I may be a little out-of-date on this, but a battery management system (BMS), especially when two or more rechargeable batteries are involved, will more than pay for itself in extending the usable life of a lead-acid (sealed or not) battery. At a minimum, the BMS will keep track of how much...
  7. hevans1944

    Trying to mount monitors Please Help

    Ditto what @Bluejets said in his post #2. More information is BETTER than less information when you are asking strangers for help. Use a program like Microsoft Paint to reduce the size of high-resolution photographic images until they will upload successfully to this site. Placing a ruler next...
  8. hevans1944

    Buzzer Circuit

    Well, yes, it was designed by Robert J. Van de Graaff, and others. And, yes, it was a tandem, a small heavy-ion research accelerator built in the 1950s by High Voltage Engineering Corporation, a company that eventually went out of business and whose designs were absorbed by High Voltage...
  9. hevans1944

    Buzzer Circuit

    Wow! You must be a fast @electronicsLearner77. I have been practicing electrical engineering "stuff" for quite awhile, although at a somewhat reduced pace now that I am "retired" and living in paradise. I wouldn't even consider designing, much less building, a variable frequency drive without a...
  10. hevans1944

    Buzzer Circuit

    I think the Original Poster (OP), @electronicsLearner77, has presented us with an over-engineered "solution" to be "tweaked" and blessed. The DSPIC33FJ32GS606 is a fairly sophisticated digital signal processor. Do you have an evaluation board with which to program and test its functionality...
  11. hevans1944

    The emitter has a higher potential than base ! How?

    Well, except in well-known cases such as electroplating of metals and electrophoresis of organic molecules, electricity is all about energy transfer and that takes place very rapidly through the means of electromagnetic fields. Electrons, holes, and ions respond rather slowly to electromagnetic...
  12. hevans1944

    The emitter has a higher potential than base ! How?

    We have already BEEN THERE hundreds, if not thousands, of times. But, you are right: let's not go there again. Besides, as any seasoned experimenter knows, all semiconductors operate on the FM principal, and if you carelessly let the magic smoke out they quit working: so, leave the smoke and the...
  13. hevans1944

    Grounding a Ham Antenna

    I have NO experience with "small" vertical antennas such as this one, but as @crutschow noted, it "looks like a nice,tall, ungrounded lightning rod." Where I live in southwestern Florida is called the Lightning Capital of the World. I, do love a nice thunderstorm, but I also get somewhat antsy...
  14. hevans1944

    A simple electric fence idea

    Ha! Ha! I never thought about doing that! But I doubt there would have been any smoke... those early induction coils could barely generate enough spark to keep a Ford engine running. I took one to school once, hidden inside a shoe box with a 6 volt screw-terminal lantern battery and a concealed...
  15. hevans1944

    A simple electric fence idea

    You and @Minder are both correct of course. But I, or the DIYer who builds this, SHOULD "feel uncomfortable working on a main's circuit." The Government uses a mains circuit to execute criminals, albeit a bit more thoroughly than the average DIYer hell-bent on winning a Darwin Competition. It's...
  16. hevans1944

    A simple electric fence idea

    I think @crutschow has presented a pretty good DIY "fencer" circuit, but for safety reasons I would use a transformer to isolate the circuit from mains power. Perhaps two filament transformers wired "back-to-back" would serve this purpose, rather than an expensive "purpose-built" isolation...
  17. hevans1944

    how to identify max forward current in an infrared LED with no spec sheet

    Carefully perform the non-destructive test described by @CircuitScoper in post #6. Repeat the test procedure on several other IR LEDs to verify the correlation between test current and junction temperature. Once you are satisfied your results are typical for several LEDs, decide how close to...
  18. hevans1944

    What optical mouse product works on a smooth surface?

    I currently use a logitech (Logi) M185 wireless optical mouse. It performs well on most smooth surfaces, except mirrors, as long as there is a textured pattern embedded in the surface. We have highly polished granite surfaces in the kitchen and in our bathrooms, but I cannot imagine wanting to...
  19. hevans1944

    Help

    @SPUD GUN: As @Audioguru said in his post #2 above, you have failed to mention ANY of the important characteristics of "a low frequency emitter capable of 20hz." Perhaps you could get a used guitar and remove all except the heaviest string, which produces the lowest note. Then tune that string...
  20. hevans1944

    electronic tubes

    Perhaps it would help us to help you if you would describe what you are trying to DO. Years ago, when I was still a teenaged electronics enthusiast with no formal training, just "book learning" in electronics, I acquired a small stash of vacuum photodiodes used in 16mm film sound projectors. I...
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