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  1. BobK

    PiC micro I/O line states

    I have no idea what you are talking about. If the pin is an input, it is not an output. It will be at the voltage supplied externally and source or sink a very small (nano amps) current. A PIC digital input that has an external voltage of about 1/2 supply can cause shoot through current in...
  2. BobK

    Arduino + Audio Amplifier Board Help

    I agree with everything @Audioguru says above. The filter must go between the Arduino and the input to the amplifier. The idea is that the Arduino puts out a series of pulses that encode the audio and the filter turns them into actual audio that you can run through an amp and speaker. Bob
  3. BobK

    PiC micro I/O line states

    Why can't you leave the PIC I/O as an input all of the time? The input current is in the nanoamp region. Bob
  4. BobK

    Arduino + Audio Amplifier Board Help

    So would I, but it is unlikely that the PWM frequency is high enough to achieve that with a simple RC filter, that is why I am going for telephone quality. A 15 KHz cutoff would likely require a multi-pole active filter, as I had observed earlier in the thread. The OP does not know what the...
  5. BobK

    You know you're a valued customer when...

    And the other 24 solved the problem of that empty drawer in your parts cabinet too! Bob
  6. BobK

    Arduino + Audio Amplifier Board Help

    Use a 100Ω resistor and two 1uF capacitors in series. This will give you a cutoff of 3180 which should be good enough to hear speech. Bob
  7. BobK

    Switches

    If you simply want to set the level of an inverter via a switch, what is the inverter there for? I don't think you have fully described what it is you are trying to do. Bob
  8. BobK

    Arduino + Audio Amplifier Board Help

    Yes, but the output from the Arduino will not be able to drive it. I might go as low as 100Ω. That would raise it to 1200Hz. You can certainly try this, it will sound like you have no highs, but it should get you sound out. You can also put caps in series to lower the capacitance. Do you...
  9. BobK

    Arduino + Audio Amplifier Board Help

    You would get a cutoff frequency of 482 Hz. Do you have any smaller capacitors? Bob
  10. BobK

    Arduino + Audio Amplifier Board Help

    Yep, That would roll off starting at 4000 Hz. Bob
  11. BobK

    Arduino + Audio Amplifier Board Help

    Sending in raw PWM will certainly cause a problem with a class D amplifier. It absolutely needs to be smoothed with at least the simple filter I proposed, and probably much more to sound good. Do you happen to know the PWM frequency? Bob
  12. BobK

    Electronics design and testing company for IoT product

    I hope you have a lot of money. or... You could try this Bob
  13. BobK

    Or gate with shift register

    An output of one to an input of the other. Bob
  14. BobK

    Please Help!!! Need circuit board that can independently fire 22 leds.

    When only 1 is lit at a time, charlieplexing is probably the best solution. 6 outputs will do it, with no other chips needed. Bob
  15. BobK

    How to build an IR-sensor from scratch?

    That's more like it! I expect the power supply had high frequency noise in the same range as the 455 KHz operating frequency. Bob
  16. BobK

    Omnidirectional Ultrasonic transmitter

    From the first line of the original post: Bob
  17. BobK

    Omnidirectional Ultrasonic transmitter

    Last time I looked LP records and frisbees were larger than 10 mm. Bob
  18. BobK

    You know you're a valued customer when...

    An empty drawer is a mythical creature in my world. Bob
  19. BobK

    You know you're a valued customer when...

    Have you considered the storage cost of the additional 15 parts? Bob
  20. BobK

    Arduino + Audio Amplifier Board Help

    Like this: And this will just get you some kind of sound, not good sound. It depends a lot on the PWM frequency. If it is 100 KHz it might work well, if 8 KHz it will be awful. You may need a much sharper filter (a couple of Sallen Key stages) after the RC filter if the PWM frequency is...
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