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  1. BobK

    clipping circuit

    Look at where your oscilloscope leads are. They are connected to ground and the sine output of the signal generator, of course you will see a sine wave. Put a resistor (1K) between the cathode of the diode and ground, and move the scope lead from the anode to the cathode, and see if that...
  2. BobK

    Cheap multimeter recommendations?

    IMHO A cheap meter is good enough for starters. 10 bucks is a throwaway compared to what you would pay for a good quality meter. I have no experience with it, but others here have said that you can get a decent cheap meter at Harbor Freight for half of your $10 budget. I have been doing...
  3. BobK

    PIC Assembly Code Not Working, PICKit2, Ultrasonic Sensor

    You need a call to Delay after the bcf in the code above. Otherwise it is off for only a few microseconds, which you would not see. Post your whole program again and maybe I can help. Bob
  4. BobK

    PIC Assembly Code Not Working, PICKit2, Ultrasonic Sensor

    The changes look good. You might want to try blinking the yellow LED the number of times that you counted before seeing the return signal. This might tell you something. Bob
  5. BobK

    PIC Assembly Code Not Working, PICKit2, Ultrasonic Sensor

    Good catch, I missed that. Bob
  6. BobK

    Display cabinet - PIR motion sensor & LED lights

    If you have 13mA at 3.2V, how do propose to get 20mA at 3.2V? You will get 20mA at some higher voltage, unknown until you actually test it. What I am saying is the if you use the minimum voltage as Vf in the calculation, you will only get 20mA for an LED that happens to be at the extreme of...
  7. BobK

    high powered LED project - newbie to electronics

    Since the video you posted, and the video within the video both indicated that it did not work, why are you bothering? Bob
  8. BobK

    PIC Assembly Code Not Working, PICKit2, Ultrasonic Sensor

    Relocatable code does not use absolute (numeric) addresses like you use in your code. You simply declare the data and the linker decides on the actual addresses. Read about it in the MPLAB ASM help. Once you get to more complex projects that have more than 1 file, it is the only way to go, so...
  9. BobK

    Beginners circuits with LEDs

    That is what soldering is for. Bob
  10. BobK

    Display cabinet - PIR motion sensor & LED lights

    Not true. The voltage required to get 20mA might be anywhere between 3.2 and 3.8V. Bob
  11. BobK

    LEDs - am I doing something wrong???

    Get LTSPICE, it is free, you can draw schematics, and then you can simulate the circuit! Bob
  12. BobK

    PIC Assembly Code Not Working, PICKit2, Ultrasonic Sensor

    Hi, and welcome to the forum. Your code looks reasonably good, but I have a few suggestions and questions. 1. Learn how to use relocatable code. Absolute code will just get you in trouble. 2. You have not set any configuration bits. This should always be done in the code, so it is...
  13. BobK

    Display cabinet - PIR motion sensor & LED lights

    The range means that the forward voltage of any particular LED at 20mA will be somewhere in that range. Each one might be different. The large range is probably due to the fact that they have several sources for the LEDs. And even LEDs from the same source will vary from batch to batch and...
  14. BobK

    Good drill for electronic work? (rating, type, ...

    I too, use a Dremel tool in a drill press stand made for it. It works great. Bob
  15. BobK

    Control the amount of current

    You are not clear. It sounds like what you really want to control is how far the motor moves something, not the current to the motor. If that is the case, you want a rotary encoder or the motor shaft, which tells the computer how far the shaft has moved. Bob
  16. BobK

    Why does my op amp sink/source current?

    So it's secret then? When asking for help, it is good manners to also answer the questions of those who you expect help from. Bob
  17. BobK

    producing 440 hz sine wave

    Yes. Bob
  18. BobK

    Lower voltage external battery pack, scam or not?

    You are correct in assuming that there must be a boost converter to get 5V out from a 3.7V battery, and that this reduces the capacity by the ratio of the voltages, plus another 10 to 15% because the converter is not 100% efficient. The lifespan is not affected by the boost converter. It...
  19. BobK

    Display cabinet - PIR motion sensor & LED lights

    The listing you pointed to said the Vf was 3.2V to 3.8V. So you are using the minimum, which pretty much guarantees that you will not get the desired current. You will have to raise the voltage to get the full current. Bob
  20. BobK

    Why does my op amp sink/source current?

    We understand how you are measuring the current. The question is how you are controlling it. Sorry, but this does not work. PWM will not control the current in the LED, except in a binary manner. During the ON part of the cycle, as much current as can will flow. During the OFF part, no...
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