Search results

  1. audioguru2

    NiCd Battery Powered LED Lamp

    I'm tired of zapping my shorted Ni-Cads. I don't think Ni-MH cells develop those crystals. It's funny that the Ni-Cads I take good care of, by removing them from the charger when they are fully charged, short and leak. But the Ni-Cads in drills and things have been over-charging for years and...
  2. audioguru2

    NiCd Battery Powered LED Lamp

    Most of my old Ni-Cads leaked or shorted so I've been using Ni-MH cells instead for a few years. The capacity of Ni-MH cells is much higher than Ni-Cads.
  3. audioguru2

    NiCd Battery Powered LED Lamp

    Good, then you can use tiny 850mA/hr AAA Ni-MH cells. They are much smaller and lighter than AA Ni-Cad cells. ;D Ni-Cads are obsolete and toxic. Energizer doesn't make them anymore. :'(
  4. audioguru2

    i need help extending the keys finder project. can someone help me out????

    Did you build it? Does it work? How far away does your whistle activate it? Does it keep beeping when it hears and is activated by its own beep?
  5. audioguru2

    led lamp

    I designed two circuits for you that had 2 AA battery cells for every 4 lighted LEDs. I hope you are correct by using 8 AA battery cells with a total of 16 LEDs. This circuit is simple and its battery will last a long time.
  6. audioguru2

    led lamp

    Hi Iceman, What are you doing? ??? You don't need the LMC7660 voltage step-up ICs when you use more than 3V. The LMC7660's, the LEDs and maybe even the battery would blow-up in your 12V circuit. The resistors would smoke too. You don't even need 12V from 8 AA cells when the 120 ohm resistors...
  7. audioguru2

    Does anybody know IC for Amper meter?

    A TL071 or TL081 opamp can operate with its input voltages near its positive supply voltage.
  8. audioguru2

    MICRO ANTENNAS

    A very extreme difference. You can't communicate very fast with a carrier frequency of only 100Hz. Morse code maybe? Higher frequencies have wider bandwidths if needed. The 486 processor in my old pc operated at 100MHz. My new one operates at a microwave frequency. The new one does a lot more...
  9. audioguru2

    Op.Amp. vs. Diff.Amp.

    Lots of ICs like linear voltage regulators and radio ICs. The timing section of a 555 timer IC operates linearly. Many circuits use Cmos digital inverters DC-biased so that they are linear amplifiers.
  10. audioguru2

    Op.Amp. vs. Diff.Amp.

    Well, a single transistor amplifer needs a lot of negative feedback to make it linear, then it doesn't have any voltage gain. An opamp amplifier has both. A two and three transistors amplifier is much better but approaches becoming an opamp. http://www.dself.dsl.pipex.com/ampins/discrete/cfp.htm...
  11. audioguru2

    basics of electrical supply

    I think that the skin effect occurs at radio frequencies beginning about 1mHz, in the AM broadcast band. I was up in an antenna mast in a tower with megawatts of microwaves there. I was given a microwave oven testing meter and was told that if it responded then to get the **** out of there as...
  12. audioguru2

    0-30 Vdc Stabilized Power Supply

    The pcb is about the same as the original. Some resistors are larger but must be stood-up from the pcb to avoid charring anyway. The driver transistor Q2 has a different pinout than the original 2N2219 but needs to be mounted on the chassis as its heatsink. A big rectifier bridge replaces the...
  13. audioguru2

    basics of electrical supply

    I disagree. Your guts conduct a lot better than your skin.
  14. audioguru2

    Op.Amp. vs. Diff.Amp.

    Individual FETs and BJTs have non-linearity. An opamp is much better.
  15. audioguru2

    MICRO ANTENNAS

    Because FM works fine at 100MHz and everyone's radio will need to be changed if the frequency was changed.
  16. audioguru2

    MICRO ANTENNAS

    I saw the history of FM broadcasting on the web. It started on a lower frequency then changed up to 88-108MHz.
  17. audioguru2

    Op.Amp. vs. Diff.Amp.

    Opamps usually operate with a linear input and output. They aren't used in switching circuits very much. Because opamps have such a lot of voltage gain, with negative feedback their non-linearity is extremely low. Therefore they are linear amplifiers.
  18. audioguru2

    dc electronic load

    Hi Alun, Good point! ;D It's a good idea to make a D to A ladder with different resistors switched by switches or Mosfets. You could use cheap Chinese toasters for higher resistance values and restaurant-quality toasters for low resistances. ;D I saw an oil-filled heater at my hardware store...
  19. audioguru2

    Coil gun charger circuit

    Hi Steven, I don't believe Dick Smith's electronic components and used car parts (hee, hee ;D) catalog. I look at the manufacturer's datasheet:
  20. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Smokey, Welcome to our forum. ;D This thread discusses modifications to the original project to make it work properly. I posted a revised parts list in this thread that has a TIP31A real power transistor replacing the little 2N2219, a 30V transformer and two 2N3055 output transistors etc. In...
Top