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  1. BobK

    BJT Ramp?

    An opamp is the right device to use for this. It can invert / amplify / offset a signal, and do it very accurately. Bob
  2. BobK

    Detecting high voltage

    My suggestion was somewhat tongue-in-cheek, as it MIGHT have been a solution, depending on how you intended to use it. But if you are happy trying to tap inside, I agree with CC that that would be a good solution. Bob
  3. BobK

    BJT Ramp?

    What is it you are trying to do? Ramp certainly does not describe the function of your circuit, inverter would be more like it. Ramp would describe a circuit whose output increased (or decreased) linearly with time. Bob
  4. BobK

    Sallen-Key Filter problem

    Those waveforms look like a high-pass filter to me. Edited to add: And filters DO re-shape waveforms. Bob
  5. BobK

    LCD Display and Operation

    Or maybe you want a digital panel meter? What range of voltages do you need to display? Bob
  6. BobK

    Detecting high voltage

    Put a low current (1ma?) fast acting fuse across it. Bob
  7. BobK

    Buck/Boost circuit for DC/DC conversion.

    Really? http://www.lmgtfy.com/?q=buck-boost+dc-dc+converter Bob
  8. BobK

    Raising 1.5v DC to 5+v DC using LM358?

    The MAX756 looks like it would work for up to 200ma. Bob
  9. BobK

    Raising 1.5v DC to 5+v DC using LM358?

    Depends on what you mean by "amplify". It you are thiking you can start with a 1.5V battery and turn it into a 5V power supply, the answer is no, you would need a DC-DC converter to do that. If, on the other hand, you have a power supply of somewhat over 5V and you want to turn a 1.5V...
  10. BobK

    is this chirping from the electrical wiring?

    I have 8 (I think the fire codes in my state must be written by smoke and CO detector vendors.) I finally gave up and started replacing the batteries each daylight savings time change, after being awakened in the night and taking like 1/2 hour to locate the chirping one, only to have the next...
  11. BobK

    can't remember the name of this chip

    Which can be discreet transistors, a specialized chip, a comparator, or an opamp. Bob
  12. BobK

    Pls HELP ME OUT !!!

    I purposely left that open. Bob
  13. BobK

    Pls HELP ME OUT !!!

    If you are experiencing symptoms like you describe, I suggest that you should see your doctor. Bob
  14. BobK

    amp and Volt meter

    Well, that is basically what it is, in a package designed for that purpose. Bob
  15. BobK

    amp and Volt meter

    And then there is the problem that the current used by the Arduino is not being counted (assuming it is running off the same battery). A high-side current sense IC would eliminate this problem and also provide the needed amplification...
  16. BobK

    H-bridge with 4 N-ch FETs

    Pick out a chip and it will have examples in the datasheet. The high-side and low-side drivers will go between your signals from the microcontroller and the gates of your power MOSFETs. Bob
  17. BobK

    VOLTAGE DIRECTLY OR INVERSELY PROPORTIONAL TO CURRENT?

    Across a resistor, voltage is proportional to current. Across an inductor, voltage is proportonal to the rate of change of current. Across a capacitor, rate of change of voltage is proportional to current. Bob
  18. BobK

    Voltage Multiplier Questions

    Yes, which allows you to use a transformer with many fewer turns. bob
  19. BobK

    Home Made Osciloscope

    It also depends on what you are going to do in the future. If you were only going to do a couple of 1-off projects, PICAXE definitely makes sense. If you are going to do a lot of different projects, or, heaven forbid, a production project, it loses it's appeal because of the limited selection...
  20. BobK

    Multi I/O timer circuit advice

    It looks like most of the original post was quoted by C.Cs first response. Too bad he did not quote the entire post. Bob
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