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  1. audioguru2

    Simple battery charger

    I have never seen a rechargable battery as small as 60mA/hrs, it would be a button size battery. A fairly small AAA Ni-MH cell is rated at 850mA/hrs. Only 3.6V is barely enough for a white LED. You would need a DC to DC converter circuit to stepup the voltage of a weakening battery and to limit...
  2. audioguru2

    Help on delay for the 4060 oscillator used in the fridge door alarm project

    The Cmos oscillator needs an Rs added as shown on datasheets. It should be 10 times the value of the frequency-determining capacitor for the formula to be fairly accurate. The Cmos ICs have an absolute minimum operating voltage of 3V. If the battery voltage is less than 3V then the oscillator...
  3. audioguru2

    Stupid amplifier!

    3.5 what? Potatoes? Eat them. ;D If both your computer AND amplifier have 3.5mm stereo connectors, then make or buy shielded audio cables with 3.5mm stereo plugs on the ends. If you don't use shieded audio cables to connect to an amplifier's input then ordinary wires will pickup all kinds of...
  4. audioguru2

    IBM T23 Notebook battery Li-ion

    Hi Art, Welcome to our forum. ;D If the Windows voltage measurement is correct, then the battery's voltage detecting circuit is sick. Sometimes the battery's circuit is inside its package.
  5. audioguru2

    amp. problem

    The amp probably has a shorted output that is causing it to draw too much supply current, get too hot and shutdown.
  6. audioguru2

    read parts

    With only 12V for the supply, you can use a 1N4001 diode for D1, any small signal transistor like a 2N3904 or BC547 for the left transistor and a TIP110 darlington transistor with a built-in turn-off resistor for the right transistor. Connect another 1N4001 diode across the stator coil to arrest...
  7. audioguru2

    Amplified Ear help!!!!

  8. audioguru2

    High grade pots?

    Hi Nid, You better wait 'til you grow up before using a digital pot. I'm an old geezer and I never grew up. I've never built anything with a digital pot but my car radio and MP3 player use them.   Spray contact cleaner into your dirty pots and let the crap drain out. Spray them a few times...
  9. audioguru2

    read parts

    Hi Guruji, Do you need part numbers for you to order them? 1) There isn't any information about the pickup coil. 2) The voltage isn't shown so the diode and transistors ratings can't be determined.
  10. audioguru2

    Simple remote gopher

  11. audioguru2

    Idea for LED Rainbow Light

    Hi Stephen, Many years ago I designed and made a bunch of slowly fading ultra-bright gadjets that shine their red, blue and green LEDs on the ceiling. I used opamps as oscillators and to make the current ramps at slightly different rates so that all colors and brightness levels slowly appear...
  12. audioguru2

    3 way speaker system

    Sorry, you said something like that: "When I tested them in properly designed enclosures with a 2x35W/4ohms or 20W/8ohms power amp they almost reached their mechanical limit below the amp's maximum power". Then its volume is too big for an 8" subwoofer. It isn't much power but maybe your room is...
  13. audioguru2

    anyone know this part no.?

    All circuits should have transistors with only 2 pins. Input and output is really all that is needed, isnt it? ??? Somebody said that a perfect amplifier is a piece of wire with gain. ;D
  14. audioguru2

    Half bridge driver

    Horray! That's right. Whenever a demand for high frequency current was requested from the power rail, its inductance of the electrolytic caused its voltage to flop to ground. Which radio frequency does it use?
  15. audioguru2

    Stupid amplifier!

    Shielded audio cables usually have RCA plugs on their ends and are used for connecting all music sources to the imputs of audio amps to avoid noise pick-up by wires like yours. Usually the noise is hum from the mains wiring in the house. If anything turns on or off there is a click. If a light...
  16. audioguru2

    Errrmmm... -VDC?

    This datasheet shows a pic of its pins, a dual-polarity power supply, a typical stereo amp schematic using it and a pcb for it: http://www.datasheetarchive.com/semiconductors/download.php?Datasheet=2007735
  17. audioguru2

    High grade pots?

    Hi Nid, Yeah, Alps are very good pots. To make a Mickey Mouse stereo pot you connect the shafts of two simple pots with a rubber band or something as a belt. Cut one shaft short so it doesn't stick out. ;D ;D Seriously, you can use a digital stereo pot. Some have control with two pushbuttons...
  18. audioguru2

    Automated lighting system

    Hi Electrobod, Welcome to our forum. ;D I don't know what is "A-level", since every country has different letters for education. Maybe 1st year of kindergarten or last year for a University PHD? Hopefully you studied the 555 timer and remote control by infrared. If not, look in our Articles...
  19. audioguru2

    Half bridge driver

    When the upper Mosfet turns off, I think the motor's very short duration inductive spike is negative, followed by considerable time when it is a positive generator. The lower Mosfet conducts the generated current therefore is a brake. True! The big electrolytic cap is an inductor at high...
  20. audioguru2

    Stupid amplifier!

    Did you use shielded audio cables for the amp's inputs?
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