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  1. OBW0549

    ECG, IRF, 2N Transistor

    Taking a wild guess at it, I'd say "no." We probably won't escape a lengthy bout of Twenty Questions, either. :rolleyes: To the OP: you've asked for information we cannot possibly provide. First, transistors don't have functions other than what they're called on to do in a specific circuit...
  2. OBW0549

    How ic fabrication is done?

    Try typing "How ic fabrication is done?" into Google. Lots of good information comes up, enough to keep you busy reading and learning for a long, long time.
  3. OBW0549

    Question about building small device with touch sensors

    Yes, it can. I would suggest using a capacitive touch sensor, such as this five-channel unit, along with a small, no-frills Arduino-like board such as this one to process the touch sensor state and report it to the host PC over USB. The rest is a SMOP (Small Matter Of Programming).
  4. OBW0549

    Microcontroller debugging

    If your PC does not have a serial port, just use a USB-to-Serial adapter to create one; any of these should do the job.
  5. OBW0549

    Microcontroller debugging

    If you Google the phrase, "terminal emulator" lots of choices come up, for Windows, Linux and Mac. On Windows I use PuTTY and TeraTerm. On the Mac, I use CoolTerm.
  6. OBW0549

    CD4093 question

    Ouch. You're right. Yeah, but I was looking at it funny.
  7. OBW0549

    CD4093 question

    What preceding gate? It's not connected to any other part of the circuit, other than ground and +5V, and is just sitting there with both its inputs high and its output low.
  8. OBW0549

    CD4093 question

    The only person who could possibly answer that question is the person who designed this oddball, non-standard hack of a circuit. There is nothing magical or mysterious about the CD4093 itself; as @(*steve*) indicated, it's just a plain, ordinary quad 2-input NAND gate with Schmitt trigger...
  9. OBW0549

    Envelope detector design

    It also has a huge Trr reverse recovery time, something like a microsecond if I recall rightly. No wonder the circuit didn't work...
  10. OBW0549

    Envelope detector design

    5 MHz is not an unrealistic frequency for materials testing, or for medical ultrasound. Take a look here.
  11. OBW0549

    Variable Frequency Op-Amp Astable

    This is something you can easily predict. You don't even need a calculator, or a pencil and paper; you can do it in your head. Imagine you have a 100 kΩ, 10-turn trimmer for VR1, connected so that at full counterclockwise rotation you have maximum resistance and therefore minimum frequency...
  12. OBW0549

    Variable Frequency Op-Amp Astable

    Your reference gives the formula for calculating frequency as a function of the timing resistor/capacitor combination, with resistance in ohms and capacitance in farads. Scroll down to the formulas shown alongside Fig. 4.2.4. As @AnalogKid noted, you're going to have a hard time getting a...
  13. OBW0549

    Envelope detector design

    Even with a very fast op amp such as the LM7171, the classic op amp-based "precision rectifier" circuit such as the one you showed is going to be completely helpless in the face of a 5 MHz input signal. As you found, it simply does not work. If you want to try making a peak detector circuit...
  14. OBW0549

    Transistor Base, Emitter, Collector -Voltage Question

    Any book on basic electronics will answer these questions for you. There is also a wealth of informative material online; just Google the phrase "how does a transistor work" and you'll get plenty of good information.
  15. OBW0549

    Transistor Base, Emitter, Collector -Voltage Question

    Yes, Vceo is the maximum voltage that can be applied from collector to emitter. No. That's the maximum reverse voltage that can be applied from base to emitter before the b-e junction breaks down. With zero or reverse b-e voltage, the transistor is off, not on.
  16. OBW0549

    LM334 Constant Current Source

    If you're measuring mA instead of μA, either your LM334 is defective or you've wired something wrong; those are the only two possibilities.
  17. OBW0549

    LM334 Constant Current Source

    LM334's are about as absolutely foolproof as you can get; your circuit on the right, with IC1 and R1, should give you an output current of approximately 194 μA at room temperature. What I can't figure out is what in the world you are doing in the circuit on the left, with P1; what's up with...
  18. OBW0549

    A question about cross talk! :)

    Quite possibly. That is one of the possible symptoms of crosstalk. For relatively slow, low-power logic such as 74HC, capacitive coupling would be the predominant mode of coupling from one signal to another. Inductive coupling is possible in principle, but I doubt it would cause any problems...
  19. OBW0549

    Problems with composite video generation!

    Excellent. This, by the way, is why people are so insistent on seeing schematics: they make design flaws much, MUCH easier to spot. Without them, finding a problem can often be nearly impossible. Good luck with your project.
  20. OBW0549

    Problems with composite video generation!

    Who the heck can possibly tell? Post a complete, accurate schematic of your circuit, and then we can begin trying to figure out what is going wrong.
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