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  1. BobK

    Function Generators Role and Effect

    Actually, this was my Halloween costume as Gomez Addams. Here is the full picture, including my lovely wife Morticia.
  2. BobK

    Sound activated switch advice

    You can get higher gain in your mic preamp by using a larger collector resistor. 10K should work, but you will have to redo the biasing as well. Bob
  3. BobK

    PIC18F4550 - Buttons and LCD

    Okay, that makes a little more sense. I would suggest that you start by writing a function that gets the next button press. I.e., when I call the function it will wait until some button is pressed and return a code for that button (1-4) for example. Then make your main function loop, calling...
  4. BobK

    Mechanical Counter - Debounce

    For a switching application, where you want saturation, a good rule of thumb is to use 10 for the gain, i.e. supply 1/10 of the collector current as the base current. Bob
  5. BobK

    Function Generators Role and Effect

    A function generator is for generating a signal for testing. It is not supposed to supply much in the way of power. You are using it correctly to apply to the base of the transistor, though hopefully this is through a resistor since the BE junction acts just like a diode and does not limit the...
  6. BobK

    PIC18F4550 - Buttons and LCD

    I cannot make sense of either your description or your code. Please explain what you are trying to do in clear language. For example: I have 4 buttons, labeled UP, DOWN, OK and BACK. The LCD displays <whatever > When I push the UP button <what happens> When I push the DOWN button <what...
  7. BobK

    Logic family selection

    In a CNC machine? :)
  8. BobK

    Portable Speaker Project

    10Ah capacity at 12V is 120Wh, 40 Watts with a normal amp (not class D) will probably use 100W and therefore last about 1 hour on batteries. If you really want this to be good I would: 1. Use LiIon batteries, which have much more capacity for the same weight. 2. Find very efficient...
  9. BobK

    sleep mode help!

    You need to turn on interrupt on change for the sensor inputs. Read the sensor inputs, then issue a sleep instruction. I will continue executing when any of the sensors changes state. You then read the sensors again to see which one interrupted, if necessary. Why don't you read the...
  10. BobK

    help in finding best micro controller

    Why use a 2N7000 with 10Ω on resistance when you can get parts with 0.1Ω on resistance for well under $1? The 2N7000 is a small signal MOSFET, not a power MOSFET. Bob
  11. BobK

    Portable Speaker Project

    First question is, why did you not buy an amp from Ebay instead of an entire car radio? It would have been cheaper, smaller, lighter, and if you got one of the class D ones, used a lot less power, probably more than doubling your battery life. All you need to do to charge the battery is put a...
  12. BobK

    LED STAIRS

    Unless you want different colors on the individual LEDs in a strip you are wasting your money on addressable strips. They cost a lot more than non-addressable ones. Bob
  13. BobK

    op-amps with high gain

    The gain of a typical op amp is around 100,000 to 1,000,000. The thing you are actually interested in is the gain bandwidth product or GBP. This number represents the max gain they can produce at any frequency. Divide the GBP by the max frequency you will need and that tells you the max gain...
  14. BobK

    Ultrathin Flexible Rechargeable LiPo Batteries

    If you could convince them that you would be placing large orders after the design was validated, you might be able to get someone to produce samples for you. Otherwise, I expect the cost would be prohibitive. Bob
  15. BobK

    Volts and Amps

    Yes, and they will tack on a charge of resisting arrest. Bob
  16. BobK

    powered computer speaker

    The dishes comes to mind. :D Bob
  17. BobK

    powered computer speaker

    I am not sure if this is what you are asking, but you cannot use a simple Y connector to connect both left and right channels to a mono map. You need a mixer in between. Fortunately, a mixer can be very simple. Run a 10K resistor from each output to the single input of the mono amp. This...
  18. BobK

    Volts and Amps

    Despite others attempts to answer, I have no clue what you are asking. Amps and volts measure two different things, it makes no sense to add one to the other or subtract one from the other. So the answer is yes, you could, but the result would be totally meaningless. For example what is 10V +...
  19. BobK

    Help to measure inrush current with an oscilloscope

    But, unless you have a Digital Storage Scope, you better read it fast! If you do have a DSO, do what Colin says, put in single triggered mode, and set the trigger level at some small voltage. Set the timing for the appropriately, maybe 10 to 100mS. Then turn the device on and you should...
  20. BobK

    Multi-Stage Amp Build

    Pretty much any op amp can do this. Doing the same 2 transistor gain stages would be damn near impossible. Bob
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