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  1. OBW0549

    Active Filter Design

    Some of your component values look rather... odd. R1 and R2 are awfully small; remember, the 741 has to drive R1 (through C2) against whatever the input signal source is putting out, and 110Ω is a VERY heavy load. R1 and R2 should both be at least 10 times larger, or even more. C2 looks like...
  2. OBW0549

    Understanding N-Channel MOSFETs

    Vgs(th) is the gate-to-source threshold voltage at which drain-to-source conduction begins. Below that voltage, little drain current flows (normally just a few microamps); as the gate voltage is raised above Vgs(th), more and more drain current flows. Needing a Vgs of 10V (or more) to get an...
  3. OBW0549

    How To Control Amperage In A Breadboard ?

    He's telling you the truth, whether you like what he's telling you or not. You cannot simply "convert" 2 amps to 2.5 amps; sorry, no such thing. If your load requires 2.5 amps, you'll need a supply capable of providing that amount of current. There's no way around that.
  4. OBW0549

    Ant Detecting Sensors

    I don't believe so. It's possible that a piezo film sensor could respond to the pitter-patter of little feet as ants scurry across. Amazon.com sells them, at least on this side of the pond. Given the extremely small vibration amplitudes involved, each sensor would have to be fed into a...
  5. OBW0549

    arduino uno R3 schematic and datasheets

    Go here, and scroll down to the Documentation section. Schematics, board layout and mechanical drawings are all there.
  6. OBW0549

    Max amperage for cable diameter

    Here's a wire table that may give you the information you need:
  7. OBW0549

    Efficient Band Pass Filter- Ideas Apperciated

    "Efficiency," "accuracy" and "error rate" are meaningless concepts when talking about bandpass filters; you'll have to be more specific about what you actually mean. By "accuracy" do you mean the accuracy of the filter's center frequency-- as in 700 Hz versus 720 Hz versus 693 Hz, etc.? Or do...
  8. OBW0549

    What's so special about mini-MELF 1N914s?

    Those are mil-spec parts, so the price reflects all the extra testing, documentation, quality-assurance protocols, and whatnot.
  9. OBW0549

    Newcomer to handling MOSFETS....

    Yes.
  10. OBW0549

    Wire color

    For mains wiring there are mandatory colors; for your own low-voltage wiring on a project, there are no requirements. I usually (but not always) use the following scheme: Positive supply voltage (e.g., +5V, +3.3V, +12V, etc.): Red Ground: Black Negative supply voltage: Blue Digital logic...
  11. OBW0549

    Judging white LED brightness.

    Minor nit: in my post above, I should have said "transimpedance amplifier," not "transconductance amplifier." The schematic below shows how I used the SFH206K in a setup to measure LED turn on/turn off time. The detector portion of the circuit uses a high-speed (100 MHz) LM6171 opamp because...
  12. OBW0549

    Judging white LED brightness.

    A silicon PIN photodiode will give you an output which is highly linear and directly proportional to brightness, unlike a CdS cell. I've used an Osram SFH206K for that purpose (grading LEDs). Use it either with a current sensing resistor or with an opamp arranged as a transconductance amplifier.
  13. OBW0549

    Output 12-30V with 20mA Electrical Source

    Is this for that iontophoresis project you referred to elsewhere? If so, passing current through the human body is definitely NOT something to be played with by amateurs; leave it to professionals who know what they're doing.
  14. OBW0549

    Tank circuit oscillator design

    First, you would have to accurately characterize the frequency shift over temperature, then arrange to adjust the value of some other component (presumably the capacitor) in such a way that the change in inductance is balanced out to maintain a constant frequency. Not an easy (or inexpensive)...
  15. OBW0549

    View angle -Phototransistor

    As Davenn said, the phototransistor data sheet does not specify the viewing angle, so there is no way any of us can tell you what it is. Here are three ways you can proceed, if viewing angle is important in your application: Contact the manufacturer's application engineers and get guidance...
  16. OBW0549

    transistors, and capacitors

    That explanation was probably in the same section you skipped over, the one where they explained that transistors are absolutely NOT anything like capacitors.
  17. OBW0549

    Ceramic Disc Confusion

    They're a useful tool, especially when you have a cap with some indecipherable markings or when you need to cherry-pick a set of matched capacitors for some odd design. I got one of these last year, and it works really well. I checked it against some precision 1% caps I keep on hand, and it...
  18. OBW0549

    I have created a circuit could anyone plz tell me if this circuit is right!!?

    The circuit is wrong.
  19. OBW0549

    Resistance and Inductance

    Yup. 22000 1/X 100000 1/X + 1/X (Display: 18032.78...) Done.
  20. OBW0549

    How ic fabrication is done?

    eBay?
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