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  1. BobK

    Negative Voltage

    Actually, the ability to do negative work. Work can also be negative. When a weight is lifted in the earth's gravitational field, it requires positive work. When it is lowered, requires negative work, which is to say that it does work instead of requiring work done on it. Charges (electrons...
  2. BobK

    Transistor voltage measurement

    Why are you measuring from the collector to the base? The more useful measurements are from the emitter to the base and from the emitter to the collector. Bob
  3. BobK

    Push button, start motor, turn off, start timer... Help with circuit and programming

    As Bluejets said, rotating by time will not work, it will get out of sync eventually and be in between the two messages. A servo would work. These rotate to a specific angle based on the signal sent to them, and they already have the gearing that Bluejets mentioned you would need. Using a...
  4. BobK

    Current Regulator

    Your question, as stated is asking for something impossible. You cannot have a current regulator that has an output of 14V and 0.1A. To regulate current, the voltage must vary depending on the load. Perhaps you really mean that the output voltage must be capable of going all the way up to the...
  5. BobK

    How does the sallen key filter work?

    What are you trying to do? Tell us the source of the waveform amd the characteristics of the load. Bob
  6. BobK

    How does the sallen key filter work?

    If I understand you, you want the filter to basically pass a DC level with some ripple. Ignoring the Sallen-Key question for now, you would do that by using a low pass filter with a corner point well below the frequency of the input. What you have as input is full wave rectified sine wave...
  7. BobK

    Vacuum in a Can

    Aw, suck it up, AG. (which is probably what you do when hungry, anyway) Bob
  8. BobK

    Anemometer switch

    The time of the switch closure is going to shorten as the anemometer runs faster, which tends the counteract the frequency to voltage relationship. You probably would want to use a one shot to make the pulses identical before going into the integrator (or what Harald called a low pass filter.)...
  9. BobK

    I need a voltage follower with >= 1Amp output for experiments

    Because one of them is always off for any particular voltage at the bases. Bob
  10. BobK

    cheat sheets

    The only comparison was my own inability to make sense of either of them. No criticism of Joyce intended. Bob
  11. BobK

    Ardiuno voltages - Beginner

    NiMH are nominally 1.2V, so you will get about 9.6V typically. But they do charge to about 1.4V so you will get 11.2V when they are freshly charged. Bob
  12. BobK

    Vacuum in a Can

    And ionize them if there is enough energy. Bob
  13. BobK

    cheat sheets

    Ted, Your posts remind me of trying to read James Joyce. Bob
  14. BobK

    Correct name for push button switch

    Pricey little buggers, aren't they? Bob
  15. BobK

    Vacuum in a Can

    Did anyone ever think about the term "vacuum cleaner?" Isn't a vacuum perfectly clean already? Bob
  16. BobK

    Resistance and Inductance

    When I was in grad school at Purdue, we had a calculator Olympics. The HP RPN people always won, until TI came out with operator precedence and nested parentheses. Then the TI people always won. Bob
  17. BobK

    Resistance and Inductance

    1 / 100000 + 1 / 22000 1/x 18032.78689 On my TI calculator Bob
  18. BobK

    Vacuum in a Can

    A vacuum pump comes to mind. Bob
  19. BobK

    Resistance and Inductance

    Uh, 1/22000 is not 5.4545... Try again. I get 18033 Bob
  20. BobK

    Decoding PWM

    Easier would be to use a remote that was not designed for something completely different. Bob
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