Search results

  1. BobK

    Increasing Battery life Question

    Not true. There are lithium ion batteries rated for 30C or full discharge in 2 minutes. These are used to power drones mostly. Bob
  2. BobK

    Nixie clock runs too slowly

    In some trim pots, the shaft rotates to slide plates that are like a semicircle across each other. In this case, turning it one full rotation brings it back to the initial setting an you can continue to do this forever. In another style, this is a screw that pushes one plate closer to another...
  3. BobK

    Question CRT TV

    You should be able to pick up a used CRT TV for next to nothing. Bob
  4. BobK

    Need a simple adjustable device to lower signal voltage?

    Okay, so the peak-to-peak voltage of the sine wave minus the offset should remain the same, only the DC offset should change. Use an op amp difference amplifier with the - input at an adjustable 0 to 300 mV and a gain of one. Bob
  5. BobK

    Need a simple adjustable device to lower signal voltage?

    So, is it the signal or the DC offset you are trying to reduce? Bob
  6. BobK

    Need a simple adjustable device to lower signal voltage?

    Depending on what you mean by this it might be very difficult unless the loading of the signal is a simple resistor. If what you really mean is the current going into the load, which I expect is the case, then it is impossible. No current can flow to the load when the voltage is 0. You have...
  7. BobK

    Controlling reset of PIC using transistor switch

    How does the Z wave module know whether you have just reset or not? Bob
  8. BobK

    For you inventors!

    12 x 0.6 / 1.5 = 4.8 car batteries. But do not despair, 3.5W is the max, the average current could be less. Bob
  9. BobK

    Controlling reset of PIC using transistor switch

    Why? Bob
  10. BobK

    For you inventors!

    That is 7.5 Watt hours. A standard car battery is about 45 Amp Hours x 12V = 540 Watt Hours. So a car battery would run it for about 72 hours, or 3 days. 10 car batteries should do it! Oh, wait, you would have to convert down from 12V to 5V and that would be about 80% efficient, so you...
  11. BobK

    Super-cheap drawing tablet - how does it work?

    Coolness factor. Bob
  12. BobK

    Extremely fast on delay timers?

    Voltages do not go through anything. Current goes through something. What is the relationship between the two questions? Bob
  13. BobK

    Programable commutator

    You cannot use a matrix like that in the general case to activate 4 relays. Say you want to activate the 4 on the diagonal. You would have to activate all rows and all columns, but this would activate all of the relays in the matrix: Bob
  14. BobK

    VFD (Variable Frequency Driver) for 3-phase motors.

    I was under the impression that 3 phase lines were run most everywhere and the transformers on the poles take 2 of the phases and convert them to 220V center tapped single phase for residential use. Bob
  15. BobK

    VFD (Variable Frequency Driver) for 3-phase motors.

    Just an off the wall question, because I have no idea. Is it possible to get 3-phase power to a residence? And if so, how much would it cost to install? Bob
  16. BobK

    Will 13v led lamps run on 12v?

    If you want to run all 8 of these off a single low voltage supply, I would suggest an LM317 based constant current source for each lamp and a 15V 8A supply. Bob
  17. BobK

    Reel to reel machine, new build or Hack?

    An Arduino is not going to have the performance and storage needed. You probably would need a ARM based micro like Rasp Pi, but hopefully with analog or audio inputs and outputs. Or, you could add an ADC externally to rasp pi. Bob
  18. BobK

    Reel to reel machine, new build or Hack?

    I could have sworn it had audio inputs, but I guess I am wrong. Bob
  19. BobK

    Useful Light Sensor for Human Gesture monitoring (TMG3991 & TSL45315)

    Interesting device. The first one includes a color ambient light sesnsor, so you probably dont need the second. From a quick scan of the datasheet, it sounds like it can detect motion in four directions. It is up to you to interpret sequences of movements into gestures. Hopefully, you...
  20. BobK

    Reel to reel machine, new build or Hack?

    A digital solution would involve an ADC to digitize your audio, memory to store it, a DAC to play it back and a microcontroller or microprocessor to orchestrate it all. A Raspberry Pi or similar small micro has all of the hardware you need. Your job would be the programming. Bob
View older results
Top