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  1. N

    Voltage Dependent switch

    By "sinusoidal envelope" you mean the envelope of the sinusoid, right? So you want the switch to be on while the envelope is high?
  2. N

    Switching Polarity of Electro-magnet.

    Just to add yet another, associated, question: How often do you want to alternate/switch it? Once a day, once a second, thousand times a second? What frequency are you looking for? . Colis, which means Inductive loads, mean spikes and phase shifts between voltage and current. This can cause...
  3. N

    Voltage Dividing Oscillating Voltage

    Your suspicion is correct. If you use a voltage divider, it will also divide the triangle waveform amplitude. Tell us about the input that has to see the 0.1 to 1.1 volt triangle wave. Particularly do you know the impedance? That is, what sort of load will it be? Also, if you need some active...
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    Lady bug robot

    So it seeks light or something? What's the main attribute of a ladybug robot?
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    Mathematics

    I have watched only a few online lectures from Khan academy, but I was singularly unimpressed with the ones I saw. It may have been the accent: I know I aam not tollerant of accents, I may have happened to statistically look at only the worst they have. Not at all a statistically siognificant...
  6. N

    Comedy Thread

    Just in case anyone cares. New Zealand has no snakes, deadly or otherwise.
  7. N

    Comedy Thread

    Sometimes you see things that make you so thankful for your upbringing :)
  8. N

    Does anyone have history with measuring linear distances?

    wheels? http://www.bosch-pt.co.nz/nz/en/measuring-wheels-213946.html Laser distance measurement? http://www.bosch-pt.co.nz/nz/en/laser-measures-131500.html Bosch laser distance measurement - used one of these for indoor data logging. Wow, I posted a link, it puts in the preview. Cool. . Just...
  9. N

    Need Help With 12v Darkness Detector

    Maybe you have done this already, but a few checks might be worthwhile. Some strips for 12v may not run at all on 9volts. Check. Depending on your battery and your LED strip, some may run a battery flat rather quickly. Worth checking.
  10. N

    Crystal sets - How do they work? :) (with real diodes)

    @Bluejets - thanks underground cable? - No, it was legit powered from induced voltage for some time. The line was 33 or 66KV. A Comms, scada shed with nothing else round, but hill country, no cable. . @duke_37, hevans1944, small signal behaviour: yes. Have a new appreciation of the workings of...
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    Crystal sets - How do they work? :) (with real diodes)

    Actually, years ago, I saw a remote comms shed under a line that was powered from a line from the otherwise unearthed metal roof. Cheaper than a transformer. Belonged to the power authority. Stories? Yes I'm not so young.
  12. N

    Crystal sets - How do they work? :) (with real diodes)

    Harvesting, no. Thanks though. It was just looking at an analysis of harvesting needing to get above the diode drops for the voltage multiplier too work that made me think about the venerable crystal set. Comment appreciated.
  13. N

    Crystal sets - How do they work? :) (with real diodes)

    I saw voltage as the problem as if the voltage does not rise on a carrier cycle sufficiently to forward bias the diode we don't get anything out. Granted it was a also a crystal earpiece, so the impedance is high. The "match" was as close to ooen, unloaded as we could get, I guess. Good point...
  14. N

    Crystal sets - How do they work? :) (with real diodes)

    Looking at requirements for energy harvesting recently, I realised that I had not appreciated fully the magic in the traditional crystal set. Perhaps someone can clarify or confirm or deny for me. . In the simplest explanation, a perfect diode, with zero forward voltage, detects, rectifies the...
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    Want to answer a few questions for my technical writing class?

    Well, the substantial truth of it is, that no way are technical people in my organisation trusted to write for the public. Anything I might contribute in that respect is "appropriately adjusted" if destined for the general public. I'd start from what I thought the general public might know of...
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    Want to answer a few questions for my technical writing class?

    What kinds of documents have you written. What do you spend the majority of time writing? Reading? Papers for IEEE & similar, for publication, technical reports, grant applications, contestible funding applications, project logs/lab books, contributions to press releases, progress reports...
  17. N

    Bc 547 vs 2n2222

    It seems in this case all you need to do to turn c-b-e into e-b-c is turn the thing round. :) Got a link to the video? Might be something subtle about it. Many transistors will work upside down, with reduced specs, sometimes you never find out. :)
  18. N

    DSP selection guide

    Arduino Due?
  19. N

    Wanted: Electronic Component Kit for Make: Electronics

    Wow, that's sort of varied. Everything from snapcircuits to robot chassis. What are you going to start with? You may find aliexpress cheaper than amazon for some things. Christmas is coming. Any local equivalent to ebay?
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