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  1. BobK

    Home appliance

    Funny, I don't see any microcontroller in your diagram, so I guess any one is as good as any other. Bob
  2. BobK

    Simple 555 synth idea

    No, a pure low pass or high pass filter does not have a resonance. A resonance would be a peak or valley in the response curve, this makes it a band-pass or band-reject filter. Bob
  3. BobK

    Please Guide

    You know, if you would answer ALL the questions, it would help. Bob
  4. BobK

    Improvised immersion

    Because it leads to both! The neutral and ground wires are connected together at the fuse box. Both are connected to the ground, through a large copper stake, as well as to the transformer. The reason for having the seperate ground connection is so that if the neutral wire happens to be...
  5. BobK

    Noob question

    Most likely they are not making contact with the battery terminals when you are not pushing on them with your fingers. Try just connecting the two end of the foil and holding it for several minutes. If nothing gets hot, there is no current flowing. Bob
  6. BobK

    Fundamental questions

    Yes, I can see it now, but it was not there yet when I was writing my response, we were writing at the same time. Bob
  7. BobK

    Simple 555 synth idea

    Active filters can be high-pass, low-pass or bandpass, depending on how they are connnected. A bandpass will have a resonance. Bob
  8. BobK

    Western Electric 1953 box of 1698 point contact transistors

    I'd guess that the crystal radio "industry" has kept the 1N34 in business. Germanium has a distinct advantage over silicon in that application. There are probably other low voltage signal appliations in which it outperfroms silicon as well. Bob
  9. BobK

    regarding capacitors as shorts for ac

    Of course the same thing can be said about a wire. It is never truly a short. Or perhaps short means very low resistance / reactance, rather tha zero, in which case either a wire or a capacitor can be considered a short. Bob
  10. BobK

    Improvised immersion

    AC also needs a complete circuit in order for current to flow. It there were a flow of current in a single wire, where would the electrons go when they hit the end? The point is that there is nowhere to go, then therefore the they would have to pile up. But they can't do that because the...
  11. BobK

    Fundamental questions

    Think of it like counting the cars that are going by on a highway. You could express this as cars per minute. Current is the the same thing, you count the coulombs of charge that go through a point in a circuit and cuirrent is coulombs per second. Direct current has the cars going in the...
  12. BobK

    Simple 555 synth idea

    If you want steeper filters, an active opamp filter is the only way to go. Each stage can do 12 db / octave, and they can be cascaded with no loss. Look up Sallen Key and VCVF filters.
  13. BobK

    Home Made Osciloscope

    You could probably build a scope with a bandwith of about 100Khz using a microcontroller, a few opamps and an LCD display. Getting over 1Mhz would be much more difficult. Bob
  14. BobK

    Improvised immersion

    It works by producing heat when a current is flowing through a reistive element, the razor blades. By the way, current does not flow in wire and out the other, it alternates between the two, which is why we call it alternating current. Bob
  15. BobK

    Mythbusters bridge resonate attempt

    Hey Wingnut, if you plan to knock down any bridges, could you let us know ahead of time so we can avoid them? Maybe even get a cool video, like this one: http://archive.org/details/SF121 Bob
  16. BobK

    Help with voltage regulator circuit, please

    You might try using a low dropout regulator and regulating down to 11V or so. The devices are likely to operate okay at 11V and this would allow your battery to keep powering them down to about 11.5V. You would need a 5A regulator. This one might do...
  17. BobK

    Stepper Motors. Any Experts?

    I am not an expert on alternators, but wouldn't the voltage drop Timescope saw be more due to back EMF when current is flowing in the coils rather than resistive? Bob
  18. BobK

    solar powered clock

    Not sure how that is going to work, unless the motor is driving the clock on a car going east to west, at about 1000MPH (depending on latitude.). Bob
  19. BobK

    Help with voltage regulator circuit, please

    A 12V regulator will not work with 12V in, much less with 11, or 10. A buck boost DC-DC converter can take a voltage lower or higher than 12V and output 12V regulated. Bob
  20. BobK

    Signal Processing

    In a musical instrument, the relative strengths of the harmonics do vary with time, and this contributes to the unique sound of each instrument. Is that what you are trying to determine? If so, you will need a very high sample rate so that you can use a small time window. If I recall...
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