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  1. audioguru2

    Electronic Stethoscope

    Correct. But the max total supply for your opamp is only 16V. it would be much easier to use a "normal" quad opamp. Suppliers deliver parts the next day. C5 prevents R14 from drawing 1.1A continuously from the output of the LM386 which would destroy it and kill the battery very quickly. C3...
  2. audioguru2

    Electronic Stethoscope

    The circuit must be re-designed to use a single supply voltage. C2 couples AC audio from the approx. +6V microphone to the 0V opamp input, so C2 always has the correct polarity. C6 couples AC audio from the +4.3V output of the LM386 to the 0V connection for the headphones, so C6 always has the...
  3. audioguru2

    Input signal for LM3915. need help.

    Your circuit doesn't need a "perfect" integrator. just a capacitor charged and discharged by the same resistor, and a high resistance load for the capacitor will be fine for your circuit. Decrease the value of C8 for a quicker response time:
  4. audioguru2

    Some kind of RPM counter

    The BP103 photo-transistors have a very wide 55 degrees pickup pattern. Any of the other photo-transitors on your list have a much narrower pattern and would be fine. I am sorry but I didn't look at all the photo-diodes. Some might be an optical emitter , others only infrared which you can't...
  5. audioguru2

    Electronic Stethoscope

    It is noisy because it is not designed to be a low noise preamp. All of its opamps are noisy. All opamps in a TL071 single, TL072 dual and TL074 quad are quieter. The TL07x opamps are designed for low noise audio, but they don't work well when a 9V battery's voltage runs down to only 6V. An...
  6. audioguru2

    best voltage and current regulator

    Your transmitter isn't going to be a generator so the LM317 doesn't need a protection diode.
  7. audioguru2

    Electronic Stethoscope

  8. audioguru2

    Some kind of RPM counter

    Hi Marc, Many of the opto items on your list are "Optical Isolators" which have its LED shining internally on a photo-diode or photo-transistor and therefore can't be used as a tachometer. Go through your list and sort them at www.datasheetarchive.com .
  9. audioguru2

    TAA Datasheet

    www.datasheetarchive.com has most datasheets.
  10. audioguru2

    best voltage and current regulator

    The resistors in the LM317 circuit have hardly any current in them so their power is also very low. I think a 3V LM317 circuit should be like this:
  11. audioguru2

    Transistor BF 494

    Maybe the power transistor SK B1382 is really a power Mosfet made by Toshiba with their part no. 2SK1382. The datasheet is available at www.datasheetarchive.com .
  12. audioguru2

    Transistor BF 494

    Hi Gogo, You can find most datasheets for old and new semiconductor products at www.datasheetarchive.com .
  13. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi again, You don't need to be a nooby if you look at datasheets for parts on www.datasheetarchive.com or other sites on the web.
  14. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Dosster, All parts are available online at www.digikey.com and www.newarkinone.com . Corrected spelling or re-phrased: 0.47 ohm/10W 12,000uF/63V Electrolytic capacitor 47uF/50V or 47uF/63V Electrolytic capacitor 100nF and 220nF Polyester capacitor 6-10 Amp/50V (or 100V) rectifier bridge...
  15. audioguru2

    best voltage and current regulator

    An LM317 won't get warm powering a 3V transmitter from 12V. Please post the schematic of the transmitter. What are you going to use it for? Have you tried it?
  16. audioguru2

    best voltage and current regulator

    No what? The battery is a lead-acid type that has an extremely low internal resistance, so it can supply many amps of current to a short or very low resistance. The transmitter operates from only 3V so its current is very low. If the transmitter operated from 100V or more then its current...
  17. audioguru2

    best voltage and current regulator

    Steev, An electronic circuit takes only as much current as it needs. The transmitter won't draw more than 20-30mA unless you short its power supply wires. Your battery is probably rated for 2.5A/Hrs, not just 2.5A. So it can probably provide 25A for a few minutes to a short or very low resistance.
  18. audioguru2

    need help finding report information

    Can you attach your project's schematic or provide a link to its article?
  19. audioguru2

    Input signal for LM3915. need help.

  20. audioguru2

    about mixer

    Here is an explanation about your tone control circuit: http://www.ecircuitcenter.com/Circuits/op_tone1/op_tone1.htm
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