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  1. hevans1944

    Car battery jumpstart gadgets

    Global warming is occurring. There can be no doubt about that. It is the normal consequence of the ending of the last Ice Age. The controversy arises when attempts are (1) made to identify the cause and (2) if necessary, promulgate an effective and universally acceptable corrective action...
  2. hevans1944

    Concurrent operation in real time embedded systems (C)

    What are the two tasks that you want to run simultaneously? Do you really need simultaneity, or is concurrently more apropos to your situation? As Harald said in his post #2, you need multiple processors or cores to execute two or more tasks simultaneously. One core, programmed to time-share...
  3. hevans1944

    Car battery jumpstart gadgets

    Good enuf for trickle charging though...
  4. hevans1944

    Using a REED SWITCH with uC Question

    Have you read, and do you understand, all 598 pages of the Atmel datasheet for your ATtiny814? What is the purpose of the reed switch? How do you awaken the processor from "sleep mode"? Which sleep mode will you be using? No. If the reed switch is closed, connecting the CR2032 coin-cell to a...
  5. hevans1944

    Car battery jumpstart gadgets

    Sure, it's possible... and right away, too, if you care to spend the money for an appropriate transformer and rectifier. This is basically what the folks pushing electric automobiles want for those who buy into their concept. Just make sure your house and garage have at least 200 A, 240 VAC...
  6. hevans1944

    Car battery jumpstart gadgets

    Two lead-acid batteries in the same car can lead to a GIANT FAIL if the weather turns VERY COLD. This battery chemistry is notorious for failing to deliver sufficient current as the temperature plummets, even if fully charged. So much for smugness under those conditions! IIRC, it does get...
  7. hevans1944

    Car battery jumpstart gadgets

    That's today's prices. In ten years or less it should be down to $50 to $200 or, if purchased in quantity from Asian manufacturers, $5 to $20. By the time it gets down to fifty cents to two bux, which I could afford on my fixed retirement income, internal combustion engines may have gone the way...
  8. hevans1944

    Car battery jumpstart gadgets

    You could probably connect the USB charging port to a small photo-voltaic solar array panel to charge the ultra-capacitors... during the daytime of course.
  9. hevans1944

    Car battery jumpstart gadgets

    What! My Hugh Hefner pose (minus the ubiquitous pipe and bathrobe) is only slightly smug-looking? And the penetrating gaze behind the all-knowing eyes... what's not to be smug about? I thought this was pretty good for a "selfie" taken in my kitchen. I graduated with a BEE degree in 1978. Since...
  10. hevans1944

    National Computer Electronic Flash Unit.

    @Alan Pearce, an electronic flash stores electrical energy in an electrolytic capacitor, discharging that stored energy into the flash lamp when the flash is triggered. Problem is, the liquid part of the electrolyte slowly evaporates, even in the best-sealed, military grade, gotta-work-right-now...
  11. hevans1944

    Car battery jumpstart gadgets

    Well, if you didn't understand @kellys_eye's explanation, maybe you are in the wrong forum. It's called a BATTERY CHARGER. See post #4 above. You IT guys think you have seen it all, so if you haven't seen it yet it probably doesn't exist... riiight? Howsabout a quote from Forrest Gump...
  12. hevans1944

    Outlet with sensor

    Sounds like a "solution" in search of a "problem." There already exist outlets with toggle switches. Just wire it so the outlet of OFF when the switch is OFF:
  13. hevans1944

    Need help with making a circuit for a peltier module

    That simplifies things a lot. You can just run the Peltier "open loop" without any temperature control, choosing a current for heating and another current for cooling. The efficiency of the Peltier is different, depending on which way the heat is flowing, so you will need to determine the two...
  14. hevans1944

    Need help with making a circuit for a peltier module

    You really need to define what you are trying to DO first before seeking a circuit design. A Peltier device moves heat from one surface to the opposite surface, the direction of heat flow depending on the polarity of the current applied to the Peltier device. If you are trying to control the...
  15. hevans1944

    Why isnt my code looping?

    @Rixen didn't post the code he actually compiled and used, just a screen shot of the program running. Don't go assuming there is anything wrong with your compiler or something. Check your code again for syntax and logic errors. Single-step through it if possible and examine whether the variables...
  16. hevans1944

    Resistance of wire seems to go down when part of a circuit?

    No, I was offered a "job" teaching basic electronics at Lowry AFB, Denver, CO after graduating from the full electronics course there in 1964. Turning that offer down was maybe the stupidest decision I had made up to that point in time, but I was anxious (at age 19) to "get into the field" and...
  17. hevans1944

    Brain storming layout for safety lighting circuit. Help.

    @Mig192: You appear to have three separate, but not necessarily unrelated, problems: (1) provide power to a microcontroller; (2) provide capability of sensing, using bit-input ports on the microcontroller, signals from external equipment, said signals being either off (0 V DC) or on (22 V to 28...
  18. hevans1944

    Resistance of wire seems to go down when part of a circuit?

    On measuring low-valued resistances with the ohmmeter function on your digital multi-meter: don't even think about doing this! When resistance values begin to approach one ohm or less, the resistance you are trying to measure becomes less (often much less) than the total resistance in series...
  19. hevans1944

    Resistance of wire seems to go down when part of a circuit?

    Literally "hair thin" in other words. And if you did manage to find some 33 AWG wire, it would likely be "magnet" wire, insulated and difficult to strip the insulation from.
  20. hevans1944

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    This wire appears to be adequate. Missed that one, but I saw images of an alleged Li-Ion battery stuffed with an inert filler instead of a real battery component. Lots of these fake as well as counterfeit batteries out there, all available at very low prices from Asian vendors. If something...
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