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  1. BobK

    Constant current LED drivers - faulty, flashing panels

    What id the forward voltage of the LED string? It sounds like you might be over stressing the driver. Bob
  2. BobK

    PICkit 3 for Programming PIC16F627A

    Pics can be programmed in circuit. All of the boards I have made have the six pin header that enables this. You can also program then on a solderless breadboard if that is what you are using. Bob
  3. BobK

    PICkit 3 for Programming PIC16F627A

    The pickit 2 only supports older obsolete parts. Use a pickit 3. Or, if budget is not a problem, ICD 3 is far better, but costly. Bob
  4. BobK

    Really basic circuit help needed (swtiches, LED, resistor and usb)

    Phones charge at between 1/2 to 2A. You cannot put this current through the LED. You need a small resistor in series with the charging circuit, then a comparator to detect the small voltage it develops when the phone is charging. Bob
  5. BobK

    PICkit 3 for Programming PIC16F627A

    You only need the pickit. Your board has to implement the connections to the 6-pin programming header. Bob
  6. BobK

    Charging NiMh battery pack with BQ2004

    ] Assuming you mean 680K and not 680Ω, your calculation appears to be correct. The datasheet says that it holds off for a while before checking the termination conditions. It sounds like it terminates as soon as it starts testing, which means one of the conditions is true right away. I would...
  7. BobK

    Really basic circuit help needed (swtiches, LED, resistor and usb)

    How are trying to detect that a phone is charging? The two switches are simply in series with the LED, but show us the circuit you are trying to use to light the LED only when a phone is charging. Bob
  8. BobK

    Charging NiMh battery pack with BQ2004

    Did you calculate RB1 and RB2 correctly? They should divide the battery voltage by a factor of 7.5 since it is expecting Vbat to be the voltage across 2 cells. I don't see anything in the datasheet about what kind of thermistor to use and what values for RT1 and RT2. How did you come up with...
  9. BobK

    Grid of tiny-linear-actuators

    No, I was just commenting on the size of an array that would have 1000 (actually 1024) actuators. If this is just intended to display a surface, I wpuld do it with computer graphics, possibly coupled with a 3D viewer. Bob
  10. BobK

    Simple Low Frequency Sound Generator

    That was fun. On my iPhone, sitting in a crowded MacDonald’s, I can’t hear the 128 sine wave until I put the speaker right ip to my ear. The square wave is quite audible though. Bob
  11. BobK

    Grid of tiny-linear-actuators

    What do you hope to do with this? 32x32 is not much resolution. Bob
  12. BobK

    Simple Low Frequency Sound Generator

    You don't specify a waveform. Different ones will sound quite different. Bob
  13. BobK

    LED specification - All about 3mm & 5mm LED's

    This is a fool's errand. You cannot rely on the size and color of the LED to tell you anything. Bob
  14. BobK

    LCD Display of Same Specification doesn't work

    Not without reverse engineering. I suggest you try to find the exact replacement if you do not have the code. Bob
  15. BobK

    LCD Display of Same Specification doesn't work

    Normally, that means initialization has not succeeded. If you are not using the busy bit, increasing delays a bit might help. Bob
  16. BobK

    Very basic resistor replacement question

    As long as it fits and the power rating is the same or higher, it is OK. No math needed. Bob
  17. BobK

    Simple Passive Stereo Mixer

    Another thought. Are you sure they are 4.7K and not 47K or 470K resistors? What is the color code? It should be: yellow violet red Bob
  18. BobK

    Simple Passive Stereo Mixer

    If you have nothing plugged in to the other inputs, you should get near full volume. If you don't, the amp's input impedance must be unusually low. If that is the case, you will need a gain stage. Bob
  19. BobK

    LCD Display of Same Specification doesn't work

    OK, that rules out the contrast issue. Bob
  20. BobK

    LCD Display of Same Specification doesn't work

    Yes. If you answer my question, I might be able to help. So, let me re-phrase it. What is pin 3 connected to? Bob
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