Search results

Search Forums New Posts
  1. BobK

    LM317 2N3055 Variable Circuit Problems

    Gomez Adams reporting for duty. Bob
  2. BobK

    Help with invention

    Cell phone processors are pretty powerful. Siri does an incredibly good job of speech to text in real time. It is fun to watch it correct as it gets more context. It will initially type out the wrong words then correct them after seeing what comes next. If you could tap into the speech...
  3. BobK

    replacing 4.7k pots with 5k on negative feedback op-amp circuit

    Why would you want to? It would most likely result in only half the range of the pot being usable before you got distortion. Unless the inputs are unusually low, in which case it might be helpful. Bob
  4. BobK

    How is IOT different from Embedded Systems?

    "Yes, exactly" is not an acceptable answer to a question giving you three options. Bob
  5. BobK

    Modified pocket calculator

    You are not going to modify a calculator to do that. The calculators you find on the market have a single chip that does it all, and it is likely not re-programmable. And even if it were, it would not have that much extra storage. What is it you really want (without telling us how you are...
  6. BobK

    LED board with shared ground and multipole PWMs?

    All you need is an inverter, which is just a simple transistor for each color. Can you describe exactly what the PWM signal is? You mention that it is active low. Is the other state high impedance or a voltage? If a voltage, what voltage? Also, what current is drawn by each color of LED...
  7. BobK

    Help with invention

    Nothing wrong with the idea, but there are existing solutions. When my father in law temporarily lost his hearing, we used a tablet with speech recognition (google) and a large font for ease of reading to communicate with him. Bob
  8. BobK

    replacing 4.7k pots with 5k on negative feedback op-amp circuit

    Changing the pot from 4.7K to 5K would increase the gain by about 6%. Not significant at all. It would not go to 11, more like 10.6 :) Bob
  9. BobK

    replacing 4.7k pots with 5k on negative feedback op-amp circuit

    I would not worry at all about 5K vs 4.7K pots. Bob
  10. BobK

    50Hz sine wave

    What voltage, what power? Bob
  11. BobK

    Solar to motor

    100 mA might be enough the run the motor, but not to start it. You could try spinning the motor once it is connected and see if it continues to spin. Bob
  12. BobK

    LM317 2N3055 Variable Circuit Problems

    Which is what I did, of course. One read 0mV the other settled over time approaching 0 (reading 6mV when I quit after about 30 seconds.) Bob
  13. BobK

    LM317 2N3055 Variable Circuit Problems

    Whoa, I did not know about "cheap" meters giving massively misleading AC voltages for DC. Both of my meters will read the ripple voltage (and they were not expensive meters, roughly $20 to $30 range) Bob
  14. BobK

    LM317 2N3055 Variable Circuit Problems

    Yes, that is a problem, you should not be reading 30V on the AC scale. Don't connect that to your circuit until it has been diagnosed. Bob
  15. BobK

    LM317 2N3055 Variable Circuit Problems

    Sound good! I suspect you were working with a damaged LM317 when you were burning those pots. Bob
  16. BobK

    Standard pitcher's arm acceleration while throwing

    Anyone up for calculating what it takes to kick a football (= soccer ball in American) the length of the field? Bob
  17. BobK

    Standard pitcher's arm acceleration while throwing

    After doing my calculation, I did an internet search and found this article: http://www.science20.com/science_20/science_baseball_what_fastest_pitcher_can_throw-51797 It claims the acceleration is something like 40g which is 40 * 9.8 = 392 m/s^2 So I guess I done good. They also estimate...
  18. BobK

    Standard pitcher's arm acceleration while throwing

    Let's see. The entire arc of the arm is probably something like 2m (the entire body moves forward as well as the arm going from pointing backward to pointing forward, so 2m is a reasonable guess. Assuming uniform acceleration (this will not actually be true, but for a back of the envelope...
  19. BobK

    ground issues with switching batteries

    You would need a MOSFET that can pass the needed current at the minimum battery voltage. Here, for example, is a MOSFET that can handle 10A with a 0.25V drop at 2.8V Vgs That sounds like about the worst case you might see. http://www.mouser.com/ds/2/302/PSMN9R1-30YL-843401.pdf Bob
  20. BobK

    12V relay with 9v battery_not working

    Why would you expect a 12V relay to operate on 9V? There is a reason that it is a 12V relay. Bob
Top