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  1. C

    A "silly" question about a resistor and a led position

    Hey Atrats. I'm no noob at electronics, and I am still confused by what people are saying here. Way too complicated. Here's my two cents: Don't think about electrons (or any charges for that matter). There are two reasons for this. The first is that in circuit diagrams and tutorials current...
  2. C

    Audio Selector

    I assume that the cards' outputs drive an external amplifier, and do not directly drive speakers. If so, then since there is no output from the inactive sound card, why don't you simply mix the outputs of the two cards together with a summing amplifier? A single opamp would do.
  3. C

    Shrinking heat-shrink sleeves

    I've successfully used a lighter flame before, and it was OK except that it tends to leave a black residue on the work and it's too easy to melt or burn stuff.
  4. C

    Pool water level stabelizer

    A sealed reed switch won't be affected at all by corrosion or electrolysis. It's easy to find glass encased ones, and as for the solder contacts outside, a bit of silicon glue will seal them nicely (just be careful when soldering glass reed switches to avoid cracking them open). The...
  5. C

    Pool water level stabelizer

    Electrode corrosion would occur, almost certainly, not due to oxidisation but to electrolysis. To avoid this, the sensing current would have to be A.C., which really complicates matters from a design point of view. My money is still on the reed switch - fix it to the pipe interior, and float a...
  6. C

    Pool water level stabelizer

    Now I think of it, mercury in a swimming pool isn't a good idea. Stick with the reed switch idea, or use a tilt switch with a ball instead. Google has all the answers you wll ever need regarding "tilt switch" and "magnetic reed switch".
  7. C

    Pool water level stabelizer

    A mercury tilt switch is a glass tube in which mecury is free to flow from one end to the other under gravity. At one end are two contacts which the mercury flows over, closing the circuit. This has nothing to do with temerature, and everything to do with position. What's wrong with the...
  8. C

    Pool water level stabelizer

    Or - perhaps even better - use a magnetic reed switch, like those used in alarm systems to detect an open door or window. I imagine you could float a magnet on the water inside the pipe, and place the reed switch in a fixed position above it. These too are sealed and exhibit hysteresis.
  9. C

    Pool water level stabelizer

    What about a mercury tilt switch? It won't corrode since it is encased in glass, and it has inherent hysteresis which would help reduce erratic switching from small waves.
  10. C

    Basic Transistor Circuits questions

    Perhaps your main concern might be noise. That will determine your choice of transistor right off the bat. Then you look at the noise characteristics of the transistor, and find out the collector current at which the transistor exhibits least noise. What about the input impedance of the next...
  11. C

    'potential Difference' questions

    Imagine water flowing through a pipe. It's the difference in pressure between the two ends of the pipe that causes the water to flow. If the pressure at the two ends is equal, there's nothing to push the water. The same principle can be used to explain the movement of electrical charges in a...
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