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  1. BobK

    Inverse multiplexer

    That would be an encoder. 74f148 is an example, 8 lines to 3 outputs. Bob
  2. BobK

    PIC16F887

    1. You can save as many numbers as you can fit in memory. For more you would need external memory of some kind, for example and SD card. 2. The pic16f887 does not support USB. You could use a serial to USB adaptor. Bob
  3. BobK

    oscillator doesn't oscillator as I expect

    Yes, most likely 4.7uH Bob
  4. BobK

    Transistors heating up when sinking from motor

    The only other thing I can think of is that you cannot get enough current through the motor to start it. The start current can be quite a bit higher than the run current. Try shorting the collector to ground with everything else the same then breaking that connection. If the motor continues...
  5. BobK

    Transistors heating up when sinking from motor

    Actually, what you are saying is consistent with the diode being backwards. The side with the band is on the connected to the + voltage and the other side to the collector? Bob
  6. BobK

    Transistors heating up when sinking from motor

    Either that or the motor really requires way more than 200mA to run. Bob
  7. BobK

    Transistors heating up when sinking from motor

    Are you sure you are using the correct pinout for the transistor? How much current does the motor draw when you connect it without the transistor? Bob
  8. BobK

    Air conditioning on a budget

    Isn't April 1 tomorrow? Bob
  9. BobK

    Photoelectric switch help

    You only have 1 wire connected to the relay terminals. You need to have two, the relay is wired just like a switch. One of the three terminals is normally open, one is normally closed and the other is common. Bob
  10. BobK

    Newbie Question - 1A at low voltage vs 1A at high voltage

    Why is 1 gallon of water per second falling 12 feet more power than 1 gallon of water per second falling 1 foot? Bob
  11. BobK

    PIC not working

    I do not see any CONFIG settings in your code. If you are setting them in the IDE it may well work, but they should be in the code so that we can see them. Bob
  12. BobK

    Multiple batteries in toys

    6 AA batteries have about 5X the capacity of the standard rectangular 9V. If it worked at all, it would work for much less time on a single 9V compared to 6 AA. Bob
  13. BobK

    Whats the difference -volts and GND (0 volts)

    Easiest way to create a split rail supply is to use 2 9V battereis. Connect the - of one ot the + of the other. That becomes 0V and the other - and + are the two rails. Bob
  14. BobK

    Musical Greeting card

    Google for "sound recording module" Bob
  15. BobK

    Relays

    The correct way to use an ammeter is to put it series with a load. If you had wanted to verify the 40mA out of an Arduino pin, the correct way would be to use a resistor, calculated to draw 40mA and put the ammeter + lead to the Arduino pin, the - lead to the resistor and the other side of the...
  16. BobK

    Automatic Night Light with solar charger

    Hi and welcome to the forum. The way your circuit is working it will draw more current when "off" then when "on". This is because you are using the transistor to bypass the LED, and just connect the resistor to ground. You need to arrange the transistor switch so that it is on when dark and...
  17. BobK

    Relays

    Never try to measure current from a voltage source by putting an ammeter in series with it! This is basically creating a short circuit. The 40mA specification is the max that you can draw without damaging the chip. As you determined it can actually produce more than that, but if you did that...
  18. BobK

    Bluetooth supply voltage

    You need a voltage regulator. Bob
  19. BobK

    Project understanding

    Most likely your PIC is not running. You need to set various configuration bits, and you should do this in the code. Bob
  20. BobK

    Low-leakage high-side switch?

    Well, with a 1000mAH battery it would only last 114 years, so I can see why you are upset. :) Seriously, 1uA is likely to be far less than the self-discharge rate of your battery. Bob
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