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  1. poor mystic

    Windtunnel Airspeed Indicator

    I think that shielding is always important when making measurements with electronics. In fact I think it should be separately earthed so that stray currents from the Arduino can't easily feed into the signal you're trying to measure.
  2. poor mystic

    Ok guys, heres another amp conversion question...

    No electrocution hazard, but there might be an impedance mis-match at the input of the amp, leading to high noise and low volume. Maybe there's be a further noise problem from the old electrolytics in the power supply. I'd put more effort into spelling and grammar, but this is a Windows phone.
  3. poor mystic

    VHF/UHF Receiver noise

    FM is almost noise-free where a carrier is present, but when no carrier is within lock range the PLL will hunt, this creates awful noise in both the bass and treble of the audio output. This applies regardless of the radio band, since the noise is in the demodulation technique rather than in...
  4. poor mystic

    Happy Birthday Davenn!

    It is still today here, Harald :) (ain't it always?)
  5. poor mystic

    Happy Birthday Davenn!

    Yes, today is Dave's birthday. I think we should double-like everything he writes all day. :)
  6. poor mystic

    Two potentiometers on a pulse width modulator

  7. poor mystic

    Transformer Mystery

    :) A signal generator, set to the proper frequency for the transformer under test, can be very useful in safely identifying transformer windings. PS I'm pretty sure the high voltages mentioned on the transformer label are the isolation test voltages. The word "gepruft" on the label means a...
  8. poor mystic

    Comedy Thread

    Electronics Point Forum has stolen a march on Failblog...
  9. poor mystic

    Transformer smoked

    Pick a lamp about the same wattage as the device under test. :)
  10. poor mystic

    Transformer smoked

    A trick I've used when testing audio amplifiers is to put a tungsten filament light bulb in as a fuse. If you have a 24V automotive tungsten filament interior light bulb you could put it in series with the load, and if there's a short in the load the light will glow brightly and the transformer...
  11. poor mystic

    Need one bit of old circuit board

    Opinion: Must be an artist. There is a lot of that stuff around. Where are you in Oz, Oh JeanGenie? I'd swap just about any amount of old circuit board for that HP calculator, and with pleasure! I'm in Cairns. :)
  12. poor mystic

    Transformer smoked

    Hi :) It might be best to measure the resistance of the mist maker, using a multimeter, if you suspect that it might be faulty. Calculating resistance: P=E^2/R, hence R=E^2/P. Then R=(24*24)/P = 576/19 = approx 30Ω However, if the device was working, it's hard to see how it could also be faulty.
  13. poor mystic

    Bike Horn

    Possibly this is one of your device's "intentional failure modes".
  14. poor mystic

    Need help with a power supply/battery circuit

    The load is say 2.5A at 5V , all up - 12.5W. Sorry, no idea. :(
  15. poor mystic

    Material detecting sensor(s) system.

    :) Can you tell us the origin of the materials? Is there to be pre-processing; is is to be in water, or on a conveyor, or or?
  16. poor mystic

    Need some help identifying this one

    I see that this particular component has a maximum reverse voltage of 15kV, and can handle a few hundred mA. Did it come from a microwave oven?
  17. poor mystic

    Need help with a power supply/battery circuit

    How much current is required by your load, and at what voltage please?
  18. poor mystic

    Need some help identifying this one

    :) Wow getting a telephone response from a component manufacturer sounds like a once-in-a-lifetime event to me!
  19. poor mystic

    Need help with a power supply/battery circuit

    Yes, I didn't read properly did I. Bad mystic! Do not pass Go! Is the GPS tracker intended to help you recover your packaged electronics if lost or stolen? Is it practical for that? - the GPS antenna has to see the sky in order to function. OK, so it is practical. How about putting an android...
  20. poor mystic

    Need help with a power supply/battery circuit

    Hi :) I think your post is excellent! I've always liked the gel cell solution. I visualise the following: A moderately large gel cell (lead acid battery) is kept charged by an automatic circuit, which self-regulates and is left plugged in as much as possible. The gel cell provides current for...
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