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  1. audioguru2

    LED Necklace

    Please attach your schematic here with your post instead of over at Flickr. Your LEDs will appear as a dim blur because the transistor circuit is missing a "peak detector" circuit. With a peak detector then each sound peak will be clearly visible. Your extremely simple circuit uses the...
  2. audioguru2

    Filters

    While they were available, I used National Semiconductor LMF40 high performance 4th-order switched-capacitor Butterworth lowpass filter ICs for many applications. The cutoff was sharp and could be tuned over a wide frequency range with the built-in clock oscillator or an external oscillator. I...
  3. audioguru2

    Help.. electronics project.

    Acoustical feedback howling is caused when the microphone can hear the speakers and the gain is high. It is eliminated by turning down the gain with a volume control, by directing speaker sounds away from the microphone or by making a recording then playing it back later. The microphone...
  4. audioguru2

    TDA7240 distortion at low volumes

    The TDA7240A amplifier has a broad range of distortion. It is typically only 0.1% but has a max of 0.5% for some of them which is pretty bad. The bad link does not work with Internet Explorer even if it is copied and pasted:
  5. audioguru2

    TDA7240 distortion at low volumes

    Your link does not work. The TDA7240 was replaced by the TDA7240A. Maybe the "A" version fixed something in the obsolete original one. It is a car radio amplifier IC, not a hi-fi amplifier. Its distortion is as high as 0.5% which is audible when its output is from 50mW to only 12W into 4 ohms...
  6. audioguru2

    LM338 Power Suply Current Regulator

    The voltage regulator uses many transistors for high power but the current regulator uses only a single LM338 that will get so hot and will shut-down when the current is higher than its setting then the circuit will not work.
  7. audioguru2

    0-30V Stabilized Power Supply

    It looks like Sam Carmel made the original version that has many faults. His mod is not shown.
  8. audioguru2

    Class D amplifier (different kind :)

    The TA2024 IC was made by Tripath. It and their other more powerful amplifier ICs were not very good. They went bankrupt over 3 years ago. Some HongKong places still sell maybe a counterfeit one. It is also used in a few kits. I don't know why American products are so expensive in Britain.
  9. audioguru2

    Class D amplifier (different kind :)

    There Are no opamps with those numbers. Maybe you mean the TL06x, TL07x and TL08x? Simply look on their datasheets: 1) The TL06x series has low supply current, a fairly low amount of gain, a low max output current and a fairly low maximum frequency of about 27kHz. They are very noisy. 2) The...
  10. audioguru2

    0-30V Stabilized Power Supply

    I added the values for the calibration trimpots:
  11. audioguru2

    0-30V Stabilized Power Supply

    The latest schematic and parts list has been posted many times. It works well, is reliable and parts for it are available nearly everywhere. Please post a link to Sam Carmel's modifications.
  12. audioguru2

    need a project idea on noise sensing

    The circuit can turn on a transistor that can apply power to any electric circuit you want, including a voice player. Make sure that the microphone is muted or cannot hear the recording so it doesn't keep it playing over and over and over and ...
  13. audioguru2

    LM338 Power Suply Current Regulator

    These simple basic questions are about translating English into your language. Maybe you should ask in your language on a website in your country.
  14. audioguru2

    computer speakers

    Hi Alun (Hero), The spec for the tiny woofer states a resonant frequency of 330Hz which is shown in the non-enlarged graph on Visaton and Rapid's sites. I posted it. But when you click on it the larger PDF graph that you posted it shows a resonance of about 270Hz which is wrong. The cheap 8"...
  15. audioguru2

    computer speakers

    The frequency response curve of the tiny speaker has an error when it is enlarged. It has a resonant frequency of 330Hz when in free air. Then it will have a response that is flat down to 330hz when it is mounted on a huge infinite baffle and it might reduce frequencies below 660Hz when mounted...
  16. audioguru2

    LM338 Power Suply Current Regulator

  17. audioguru2

    LM338 Power Suply Current Regulator

    We forgot that the regulator has the 197mA current in the 4.7 ohm resistor plus the 160mA base current of the transistors. So the regulator dissipates 11W and each transistor dissipates 35.8W each. 
  18. audioguru2

    LM338 Power Suply Current Regulator

    If you set the current regulator to 5A and load the power supply with less than 5A then the current regulator is saturated and does not get hot. But if you have a load that tries to draw more than 5A (maybe the output is accidently shorted) then the current regulator will have its max current...
  19. audioguru2

    LM338 Power Suply Current Regulator

    Yes but then its output voltage must never be less than 37V. If you connect a load that tries to draw more than 5A then the current regulation will reduce the output voltage until the current is 1A. Then the LM338 current regulator will dissipate as much as 40W!
  20. audioguru2

    LM338 Power Suply Current Regulator

    The voltage regulator and current regulator will have 30V or more across them sometimes. An LM338 limits its current when it has more than 10V from its input to its output. Then its max current is only 1A. With a voltage of 30V and a current of 1A then it dissipates 30W, not 3W. A "150W" power...
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