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  1. BobK

    NE555, LM7805, and MC34063

    You should not need any of those for wireless energy transfer. You basically need an oscillator, an amplifier, and a coil fot the transmitter, and a coil, capacitor, and diode for the receiver. Bob
  2. BobK

    sleep mode for PIC

    Depends on what is connected to the ports. For example, if there is an LED beteen V+ and the port, you would set it to high to minimize current, Bob
  3. BobK

    Pull up resistors in PIC Microcontrollers

    They are used to avoid the need for an external resistor. For example, switch inputs require a pullup or pulldown so the state of the input is defined when the switch is open. That said, I have just made a board using a weak pullup for a switch input, and I can trigger the switch by touching...
  4. BobK

    Digital Signal Is Transmitted?

    Morse code is using ones and zeros! They just call them dots and dashes. Bob
  5. BobK

    LCD Display (Basic)

    Yeah, I doubt that they would even talk to someone who wants to buy 3 or 4 of them. Bob
  6. BobK

    LCD Display (Basic)

    These exist commercially. Way cool. No battery! Updated by RF. http://www.usocard.com/Product/NFC_Series/NFC_Sticker_Tags/030J22017.html There are others. Search "electronic shelf label" or "digital price tag." Bob
  7. BobK

    Digital Signal Is Transmitted?

    As ones and zeros. Bob
  8. BobK

    Multi meter question?

    As someone who keeps extra fuses for my meters in stock, I can testify that mistakes are made! Bob
  9. BobK

    Looking for a high current darlington transistor.

    Here for instance. Current handling 180A On resistance 2.4mΩ. At 20A this would dissipate 48mW, it would not even get warm! This only applies though if it will be all ON or all OFF. If linear operation is needed, MOSFETS do not have such an advantage over bipolar transistors unless it...
  10. BobK

    Looking for a high current darlington transistor.

    When you say pass transistor, do you mean it will be in linear mode, as in a vpltage regulator, or is it simply an on/off switch? If it is the latter, a MOSFET is far better as there are some that can pass 20 amps without even needing a heat sink. Bob
  11. BobK

    Press a button to start a timer project? Thanks.

    Agree that for someone who is not experienced with microcontrollers, the task is daunting. But for someone like me, who has all the necessary tools, knowledge, and experience, it is a no- brainer. Bob
  12. BobK

    Touch activated torch - increase sensitivity

    Changing R2 will not effect the sensitivity. To make it more sensitive, increase R1. Bob
  13. BobK

    Connect several wires without relays?

    Depending on what you mean, the button itself can do all of that. Does a single button make / break multiple connections on only a single one? It the change momentary or latching? Bob
  14. BobK

    Press a button to start a timer project? Thanks.

    Yes, if I were doing it I would use a PIC and it would cost less, have fewer parts and be more amenable to changing it's behaviour if desired. What of those attributes do you take issue with? On the other hand, using a calculator with a transistor across the "=" button seems pretty ridiculous...
  15. BobK

    Increase dc voltage

    Use an NPN or N-channel MOSFET. Look in the resource section of this forum for info on using a transistor as a switch. Bob
  16. BobK

    Doubling capacitors in flash?

    Just get a more powerful flash. Bob
  17. BobK

    Multi meter question?

    I have two inexpensive but not cheap ($30 - $50) meters. They agree to ± last digit. And I have had not trouble with either of them. I can't see $100s for a meter. Bob
  18. BobK

    Doubling capacitors in flash?

    Twice the light = 1 stop higher = better depth of field. Bob
  19. BobK

    Particle swarm LED lamp

    Interesting project. It might be interesting to think of a purely local algorithm, where each node communicated only with near neighbors. I would think swarming behavior could be modelled that way. Bob
  20. BobK

    Doubling capacitors in flash?

    It might overdrive the flash tube and destroy it. Even if it doesn't right away, it would likely shorten its life. Bob
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