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  1. audioguru2

    high voltage photo flash capacitor charger

    Hi Steven, Didn't you say that your capacitor is fully charged when the neon bulb lights? A neon bulb lights with only 85 to 90V. Aren't you charging the capacitor that is rated at only 330V with the thousands of volts that should come from the flyback transformer? What will happen to the...
  2. audioguru2

    Weird circuit

    Huh? That's weird. How can the feedback produce the same change in base current as the signal source, unless it is positive feedback? I've always thought that negative feedback cancels some of the input, therefore reducing gain. Where's the circuit that "you posted"?
  3. audioguru2

    Audio Project 16 10W Mini Audio Amplifier

    Mixos, Could you please add a link to this discussion in the project's text.
  4. audioguru2

    Can it work?

    Hi, This amplifier is designed for a 32V supply, so certainly won't give much power output with only a 12V supply. 10W into 8 ohms is a voltage swing of a little over 25V peak-to-peak. So the voltage loss in the circuit is a little more than 7V. If you have the same voltage loss with a 12V...
  5. audioguru2

    Audio Project 16 10W Mini Audio Amplifier

    Hi Ante, Never mind feeding a signal into this little amp. To avoid crossover distortion, each TDA2003 idles with up to 50mA. It ain't no low-power LM358! Also, the author of ths project and I completely forgot that the minimum voltage rating of the TDA2003 is 8V. So a brand new PP3 alkaline...
  6. audioguru2

    Electronic Stethoscope 2

    Hi Prateek, I am glad to hear that your project is also working well. I am sorry that you wasted "3 precious months of my college life working on this project", until I fixed it. Before you also said that the ICs that I recommend were difficult to obtain. How did you get them? The LM386 that...
  7. audioguru2

    Vertical line test questin

    Hi Quantum, I asume that the vertical line is the test that is made on video systems to determine reaction time and overshoot of the electronics. A real life situation would be that you are driving a car (or riding a bike) down the street and a small child jumps out in front of you. You and...
  8. audioguru2

    Electronic Stethoscope 2

    Hi Doctor Emad, 20nF won't make much difference and 100nF will cause the filter to filter-out most frequencies. 4.7nF will make a big difference. I am glad that you find my corrections to this project to be working well. You can post the circuit anywhere you want.
  9. audioguru2

    Audio Project 16 10W Mini Audio Amplifier

    Hi Ante, Sure a 9V battery will supply a bridged 10W amp. Especially if it is made with 6 alkaline D cells. I used my bridged amp for years at the beach, and it was powered by only 6 Ni-Cad AA cells (5W into 4 ohms, the bridged amps had bootstrapping). Even a small rectangular "transistor" 9V...
  10. audioguru2

    Audio Project 16 10W Mini Audio Amplifier

    Hi John, The schematic is probably the same as the one in the datasheet for its TDA2003: http://home.eunet.cz/rysanek/pdf/tda2003.pdf The author of our project had wishful thinking when he stated 10W. He should have said that the circuit is capable of providing 10W, when it has a 14.4V supply...
  11. audioguru2

    part replacement

    MP, Good point! Reducing the output level effectvely extends the high frequency response to well over 20KHz. I was going to ask how are we going to keep the output level down during sound peaks (limiter?) until I saw on the mixer's schematic that it has a maximum gain of only one. With...
  12. audioguru2

    ERRORS

    I couldn't get in about 2 or 3 hours ago, but it works now. The new button appears only with some JPG images, not all of them. I am sorry that I was mistaken when I said that it disappeared completely.
  13. audioguru2

    part replacement

    Hi Trigger, Yes, I am aware that far east semiconductor manufacturers copy American ICs and make them better. The KIA358 that you posted has an extended response all the way to 8KHz! Wow, that's nearly half the audio band. At what expense? How's its stability? It still has the bases of its...
  14. audioguru2

    help with LCD power

    MP, You seem to operate regulators right at their minimum limit. You had the same problem with the LM317. The datasheet details that I posted clearly show that it has a typical Input Voltage Regulation spec that is 3 times better with a 3V differential, and they don't even guarantee a Ripple...
  15. audioguru2

    part replacement

    Hi Trigger, You think that an LM324 is bad for audio? The LM358 is exactly half of an LM324:
  16. audioguru2

    part replacement

    Which half-decent piece of manufactured audio equipment uses a noisy, distorted old LM358 or LM324 in its audio path? I am not talking about a narrow-band sub-woofer amplifier. Show its S/N ratio and distortion at full output from 20Hz to 20KHz like all audio equipment does. Its datasheet shows...
  17. audioguru2

    part replacement

    Hi Trigger, Have you heard the noise and crossover distortion from a "low power" LM358 dual or LM324 quad opamp? It is very noticeable at higher audio frequencies where it doesn't have enough gain for negative feedback to reduce it. Due to its low power, it doesn't have enough bias current for...
  18. audioguru2

    Question on the Plants Watering Watcher circuit

    Hi Dicky, The waveform between the probes is a fairly symmetrical signal to avoid the plating/deplating action that would occur with DC or asymmetry. I don't think that sine-wave or square-wave would make any difference, as long as it is symmetrical so that the average voltage is zero.
  19. audioguru2

    help with LCD power

    MP, Sorry to disagree, but the 2V dropout voltage is when it doesn't regulate any more. You didn't read the spec's details:
  20. audioguru2

    Question on the Plants Watering Watcher circuit

    How can I reply when the moderator keeps deleting my posts! The Plants Watering Watcher-2 circuit dims the LED with pulse-width-modulation. The LED doesn't have a threshold voltage, it dims smoothly from very bright to fully-off, depending on the AC impedance of the soil.
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