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About pnemeth

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  • Birthday 03/03/1990

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  1. Though if you're serious about short-wave listening, a DSP filter is pretty much a must, especially for daytime listening. Those are tricky to build.
  2. Some good stuff on
  3. The power supply seems like a nice place to get 6v from a computer. A 7805 with its com pin pulled to ground across a diode will give you ~6v. Parallel port voltages tend to be between 3 and 5 volts, and current output is too low to really be useful.
  4. Actually, the LCD itself is standard, and the interface usually is too. The only difference is they use their own plug. It's still svga/dvi, you just need the pinout and a soldering iron. No, the LCD itself is not standard, but I don't really see how that matters, as nobody is going to want/be able to make thier own LCD controller. And why on earth would a laptop manufacturer ever use svga input to an lcd? That would require changing the origianl siganl from digital to anaglog, only to be changed back to digital (with quality loss all along the way). DVI is doable, but it's still doubtful that the LCD controller on the laptop will be designed for that kind of input. Laptop LCDs are not made to be user friendly.
  5. I can hear, so can my brother, and so can my 46 year old parents.
  6. omg n00bs get an hp
  7. just go to radio shack and buy a 10 ohm resistor with a large power rating (10 watts should work fine), and use it to discharge all the capacitors. Then you can poke around without worrying about getting zapped. btw, since when is volts a unit of charge?
  8. Sorry, I must have missed your edit. I suppose that method would work but it would take a lot of guessing! Not only do you need to build circuits for a bunch of frequencies, but the laod capacitances vary between manufacturers making it even trickier! If the crystal was in a circuit the easiest thing to do is proably just to leave it there and try to find the output of the xtal circuit (probably off some inverter?) and just test the frequncy there. When you think about it, this whole topic is a bit absurd. If for some reason you just had an unmarked crystal sitting around, why would anyone feel the need to test it? Just on the off chance that it might have a resonant frequncy that you need in some project? I would just by a new crystal for 18 cents!
  9. Well tell me if I'm missing something, but i can't get your method to work. Heres a test case: You have an unmarked crystal that has a resonant frequency of 2mhz (but you don't know that). Using the guess and check method, you obtain the frequncies of two harmonics, 4mhz and 6mz. Using your method I end up with this: b=4/m1 b=6/m2 substite for b and you have this: 4/m1=6/m2 You still have two unknowns. Please tell me if I am missing something, but that is unsolvable (at least by me). Anyways, there are lots of resonant frequencies that could have harmonics in common. Example: a 2mhz crystal and a 4mhz crystal both share the harmonics 8mhz and 12mhz.
  10. Don't confuse them with canned oscillators, which are active compnents that you supply power to, and they output some waveform (usually square or sine) at a specific frequency.
  11. I don't really see how you would boost the signal without adding higher gain antenna.... I would open it up and see how easy it would be to attach a directional antenna or something. Test Points, probably. EDIT: fixed fucked up quote tags
  12. --double post--
  13. No, becuase first you would need to get the thing oscillating and the feedback circuits are different depending on the frequency of the oscillator. You could use guess and check but, as routermonk said, you wouldn't be sure wheather it was osciallating at its resonant frequency or some weird harmonic.
  14. El Cheapo Programmer by Myke Predko But the real question is why are you using PICs when you could be using AVRs?