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  1. BobK

    Controlling Drill Motor Speed - Universal Motor

    A standard dimmer switch would probably work okay. Bob
  2. BobK

    Need Tech Brains!

    If you want someone to make this for you, you better have deep pockets. It is a lot of work. And you would probably need different people for the electronics and the artistic and mechanical design. Bob
  3. BobK

    Need Tech Brains!

    The more I think about this, the more I think a solution isn't that difficult. An IR transceiver under each square and in the bottom of each piece would handle all of the communication. And a master micro or single board computer like the Raspberry Pi would run the show. All of this could be...
  4. BobK

    Pc to Relays

    Google "USB relay board" Bob
  5. BobK

    tinyTesla: DIY kit for beginners

    The output of the Tesla coil is probably safe, because it is very low current and high frequency. The input is not. It's a capacitor charged to several KV. Discharging this capacitor into yourself could be fatal. Bob
  6. BobK

    Help with making EMS

    This sounds very dangerous and probably illegal to build and use. Bob
  7. BobK

    Lighting Galaxy Quest Ship...Have magnet question

    Or a very thin carbon nanotube. Bob
  8. BobK

    VU project

    There are LED strips with addressable "pixels". You can control all of the LEDs in the strip independently with only 1 wire (in addition to power and ground). But this would require a microcontroller to send the signals to the LEDs. Look for WS2811. Bob
  9. BobK

    Help for my first proximity sensing project.

    In addition to Gryd3's questions: Are they in line of sight, or must the signal go through obstacles? Bob
  10. BobK

    relationship between Switching charge (Qsw) and MOSFET loss??

    The main thing is how much current you can supply to the gate. For fast switching of high powered MOSFETs more than 1A can be necessary to keep switching times low. Zero resistance if okay if the driver can handle it. Bob
  11. BobK

    PWM to Sine Wave Converter

    Are you sure your screen shot is PWM, it looks more like PPM. The pulses seem to be the same width with differing timing shift. A PWM signal that represents a sine wave can be turned into a shaggy sine wave by using an RC filter. You would put the corner frequency just above the frequency of...
  12. BobK

    PIC weak pull-ups on battery power with voltage divider

    Two diodes between battery + and Vdd might provide a more stable voltage than a resistive divider. Bob
  13. BobK

    A few beginners questions

    Did you try some of the online battery sites? They will have replacements for any size you can imagine. Bob
  14. BobK

    how convert squarewave to sawtooth wave

    Try googling it. A monostable multivibrator will go high when it sees a clock pulse and stay high for a period based on a capacitor and resistor. A '555 can do this, but, as I said before, it will probably not reach 1MHz. Bob
  15. BobK

    Modifying Voltage Regulator Design !!!

    Good point. Bob
  16. BobK

    A few beginners questions

    Okay, it is charging in parallel then. The bad battery is probably eating up most of the available current. Bob
  17. BobK

    how convert squarewave to sawtooth wave

    You could do that with a monstable circuit. If the period of the monostable is adjustable and less then then period of the sqarewave, just trigger on the rising edge of the sqarewave and adjust the period to get the desired pulse width out. Bob
  18. BobK

    Modifying Voltage Regulator Design !!!

    Use an SPDT switch to switch between the two resistors, one for 1.0V and one for 1.2V. Bob
  19. BobK

    A few beginners questions

    Does the charge light come on if less than 4 batteries are inserted? If not, it is probably charging in series. Bob
  20. BobK

    how convert squarewave to sawtooth wave

    Actually, an integrator, without additional circuitry, would give you a triangle wave. You need something to short the capacitor at the end of the cycle in order to get a sawtooth. A '555 with a constant current source to charge the cap would work, but probably not at 1 MHz. Bob
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