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  1. BobK

    Make a mouse fence that kills mice..in the celing!

    Nerve gas. No damage to the house at all. Bob
  2. BobK

    Can you help me develop my invention?

    Actually WiFi would make more sense for what you want then bluetooth. It has the range to cover a whole house. By the way, I suspect your invention already exists. Bob
  3. BobK

    Help needed to make 555 timer circuit throw relay.

    What are the voltage and current requirements of the relay? The diode goes in reverse across the coil of the relay. It's purpose is to suppress a high voltage spike that occurs when the coil is turned off. Bob
  4. BobK

    Newbie Project

    Taking it apart is not a good way to learn how it works. I will be very difficult to correctly draw the schematic, you will likely have difficulty identifying all the parts, and even if you have the correct schematic, you will not, as a beginner, be able to learn anything about it without a lot...
  5. BobK

    Maximite colour computer

    I might have to build one of those! bob
  6. BobK

    4049 circuit

    Let me google that for you. Bob
  7. BobK

    Total amateur question.

    So set the pin to high when you go to sleep! Bob
  8. BobK

    Powering device with batteries

    Okay, then it should be fine. Bob
  9. BobK

    Powering device with batteries

    It better be: I worry that this is a very expensive solution that might not work at all. Bob
  10. BobK

    Compatibility serial devices

    Try typing "Oscilloscope tutorial" at youtube. Bob
  11. BobK

    Resistor help

    A picture would help. Note that just replacing the resistor will not necessarily fix the tv, it probably blew for a reason, and if that reason is still there, the next one will blow as well. Bob
  12. BobK

    Powering device with batteries

    3 or 4 D cells would get you about 6 hours of operation, if that is helpful. Bob
  13. BobK

    School Project Help.

    If I remember correctly, a long tailed pair with an variable current source on the emitters works as a variable gain amplifier. Bob
  14. BobK

    Common Emitter Amplifier turns into AM radio

    Actually, resonance is probably not needed. Any diode can be an AM detector, and you will just hear the strongest station at the location. In this case, the diode is parf of the transistor. Bob
  15. BobK

    Battery Drainer Circuit

    Read more about the Joule Thief. It drains the battery down to a few tenths of a volt while still lighting the LED far more efficiently than your circuit, without a need to keep adjusting it. The resistor in the Joule Thief is used for a different purpose than in your circuit. Bob
  16. BobK

    9V Power Supply Amperage

    Unless you are using rail-to-rail amps,. your +-4.5V supply will only give you a swing of about +-2V which might be limiting. I would go with +-9V, or use only rail-to-rail opamps. Bob
  17. BobK

    Model engineer needs help

    Yes, rail-to-rail opamps rock for single low voltage applications. Bob
  18. BobK

    Frankenstein's Components.

    I would like to know if anyone has taken out an LCD screen from one of those incredibly cheap digital picture frames? If so, what kind of interface does it require? Bob
  19. BobK

    assistance with modifying pc power supply

    That cannot possibly work. How did you wire it????? What was wired to gnd? The -12V I presume? Then how could it be that one of the 12V lines would supply 24V and the other one only 12V? Also the -12V can only supply 0.3A, so how do you expect to get 6A out of it? You are lucky the...
  20. BobK

    Help for School Project

    It is kind of hard for anyone to give that kind of advice without knowing if the "robot" is 100g or 100Kg. Perhaps you could give a few more details. Bob
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