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  1. BobK

    Snowstopper

    Please help. I want to make an electronic device that diverts snowstorms around my city. I have made many things with LEDs. Bob
  2. BobK

    No voltage drop

    How about telling us what you measured and why you think it is wrong. Bob
  3. BobK

    No voltage drop

    You are using the term voltage drop incorrectly, which makes it hard to understand what you are saying. I think you are saying that you have a power supply that has a voltage of 12.2 V when not powering anything, and when you use it power your board, it measures 1V. If this is the case you...
  4. BobK

    Amplifying Millivolts to Volts

    So, let me see if I have this right. You have a power source that puts out 10mV at some unknown current, and you want to boost (not amplify, that is a different thing) this power to 5V to charge a phone. When you boost a voltage, you diminish the current by the same factor (actually more...
  5. BobK

    Home made PCB's

    I actually have modified a laminator now to make the process more reliable and I got very good results the first couple of times, but it seems to have degraded for some reason. With the laminator, blue transfer sheets made the best images. Bob
  6. BobK

    MOSFET protection help.

    I would say they were being over cautious. Bob
  7. BobK

    Home made PCB's

    Look at this thread for a DIY board done with toner transfer: https://www.electronicspoint.com/build-device-schematic-diy-pc-board-t257052.html Bob
  8. BobK

    Eagle HELP PLEASE

    Perhaps, then, you should learn how to use Eagle to do that. Here is a tutorial that might help: https://learn.sparkfun.com/tutorials/using-eagle-board-layout Bob
  9. BobK

    Meat Balls

    Serious? I can do that. 1 pound of ground beef, one medium onion chopped fine and sautéed, 1/3 cup bread crumbs and 1/3 cup of milk. Salt and pepper to taste. Mix the breadcrumbs and milk and allow to thicken. Then mix all the ingredients, and form into balls about 1 inch in diameter. Cook...
  10. BobK

    Board etching

    Etching is done with chemicals, not a laser printer. A laser printer can be used to transfer a toner pattern to the PCB before it is etched. Other methods of putting the pattern on the board are drawing it with a resist ink pen, using photo-sensitive boards and exposing them through a film...
  11. BobK

    MOSFET protection help.

    The diode does not need to be especially fast. It should be rated at a voltage higher than the coil is driven with and handle the more then the current driving into the coil. For 1A currents, a 1N4001 would be fine. Bob
  12. BobK

    adjustable pulse sender

    It would be called a pulse generator. An NE555 could probably do what you need. What is the voltage, frequency and width of the pulses? Bob
  13. BobK

    maximum power transfer

    Arouse, I hate to belabor the point, but I can't see that the answer (an equal resistor) is possible for the question he asked. He is talking about a speaker of fixed impedance in series with a resistor that you can choose. If you can choose the resistor, the answer is always 0. The...
  14. BobK

    Meat Balls

    The angle of the dangle is equal to the heat of the meat time the mass of the ass? (I doubt that this thread will live very long) Bob
  15. BobK

    Battery pack with indicator

    Agree, the correct units should be used. I cringe every time I see a newspaper article about a new solar installation that says it will produce 10 Megawatts per year. The always seem to get power / energy units wrong. Bob
  16. BobK

    Battery pack with indicator

    Why not use an 11.1 V (3 cells) and call it even? It would likely work quite reasonably with a 12V device.
  17. BobK

    maximum power transfer

    But that is not what he asked. He is asking about putting a resistor in series with the speaker, then presumably connecting it to an amp. You will get the most power to the speaker with 0 Ohms as a series resistor. I think he really wanted to ask what you are answering, but phrased it badly...
  18. BobK

    Battery pack with indicator

    Although he is using the wrong terminology, the effective capacity of the batteries does scale the same way as the current draw. I.e. if I am drawing twice the current needed to operate the device, I can basically derate my battery capacity by a factor of 2. So 3000 mAH batteries will act like...
  19. BobK

    maximum power transfer

    Finding a zero in the derivative will not help in this case. The max will be at an endpoint. I think the question is phrased wrongly. The way it is phrased, putting a resistor in series with a speaker, the answer of what resistor will result in the most power transfer (to the speaker...
  20. BobK

    Beginner Electronics - Cree LED circuit

    Also be aware that 5 of those LEDs will produce about 3 lumens. A typical LED flashlight is more like 100 lumens, so don't expect it to be very bright. The reason LED lights use more complicated circuits is for efficiency and consistency of the light output. Typically, they would use a buck...
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