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  1. audioguru2

    Class D amplifier Applications

    Class-D amplifiers are used in audio systems that need a low battery current and/or as audio amplifiers that produce low heating that is needed in LCD monitors. Texas Instruments make many class-D amplifier ICs.
  2. audioguru2

    Audio Guru FM TX

    330nF is a very common film capacitor value. For which capacitor? That will be fine.
  3. audioguru2

    simple question about batt chargers

    Hi Walid, Read the tutorials about rechargable batteries at www.energizer.com . On the 1st page, click on Technical Info near the top, then on the 2nd page select Ni-Cad or Ni-MH type. Then look at the PDFs of charging and discharging. The voltage changes with chemistry, temperature and the...
  4. audioguru2

    90 degrees phase shift

    No. An integrator is also a lowpass filter and will reduce distortion. Use an Allpass filter with its amount of phase-shift adjustable for the frequency.
  5. audioguru2

    Veronica PLL

    I haven't tried it and haven't read a comparison, but I think the FRB circuit is more modern than the Veronica PLL.
  6. audioguru2

    Sound Level Indicator

    Correct. Yes. With a 9V supply, 10 LEDs drawing 27mA each through the LM3915 and 2V LEDs, the LED driving circuit must dissipate 7V x 270mA= 1.89W. The LM3915 will overheat. The 10 ohm resistor will dissipate 270mA squared x 10 ohms= 0.73W, so the LM3915 dissipates the difference of the total...
  7. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    Hi Was, This project can be a dual-polarity supply and a doubled output voltage supply by simply making two of them with separate transformers and completely isolated from earth. Then they can be wired in series with their junction as "ground" and the positive and negative voltages from each...
  8. audioguru2

    about mixer

    I don't see an LED in any of the preamp circuits you attached. Please attach its schematic again. I don't know what is an audio repeater. Please describe exactly what you want it to do. A fuzz circuit adds severe distortion to a guitar preamp. Then the guitar makes a buzzing sound instead of a...
  9. audioguru2

    Darlington TR

    Reduce the effect of Miller capacitance by operating a transistor in a high frequency circuit with a low-value collector resistor and input impedance. These are accomplished with operating at a fairly high current.
  10. audioguru2

    500W 12v to 220v Inverter

    Hi Doron, Something must be wired wrong for the CD4047 to get hot. It is Cmos which has an extremely low operating current at such a low frequency and its opamp load draws nearly no current. Didn't you make an oscillator like this one that is on the modified version?
  11. audioguru2

    Darlington TR

    The hFE of a 2N3904 at 1.0Ma collector current is a minimum of 70, the text doesn't have a typical hFE but a graph shows a typical hFE of 230. With VceQ of only 0.5V then the transistor can't do anything useful. Its power dissipation is only 0.5mW (not 5mW) if you need it to operate at such a...
  12. audioguru2

    voltage across 2 terminals of diode,transistor

    It shows that the diode or transistor's junction is working properly. When it is forward biased and conducts, then the voltage is about 0.7V and when it is reverse-biased, then it doesn't conduct. The forward voltage changes a little with current and with temperature. When it is very hot then it...
  13. audioguru2

    Darlington TR

    Hi Shahzad, "hFE" is a transistor's DC current gain that is different for each transistor that have the same part number, the range of hFE for a 2N3904 transistor at 10mA collector current and 1.0V Vce is 100 to 300. It is measured with the transistor conducting as a linear amplifier, not...
  14. audioguru2

    Darlington TR

    Your transistor isn't doing anything with such a low output level. I showed you that the output doesn't clip until the level is 180 times greater than you have.
  15. audioguru2

    Darlington TR

    With R2 as 18k the output is much better and isn't clipped at the bottom, but is beginning to clip at the top. It is best with 20k but I won't show it because 90k is not a standard resistor value.
  16. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    The project that is modified for 5A is the same as the 3A improved circuit, except has 3 2N3055 transistors with 0.22 ohm or 0.33 ohm emitter resistors, R7 is 0.27 ohms/10W, C1 is very large and the transformer is 30VAC/7.1A.
  17. audioguru2

    Digitally selected outputs for LM317

    You are making your own D to A converter. Look it up in Google.
  18. audioguru2

    0-30 Vdc Stabilized Power Supply

    The thread for modifying the project to a 30V 5A output is here: http://www.electronics-lab.com/forum/index.php?topic=196.0 A few people have attached their schematics. The final parts list isn't posted. In this thread I have this recommended parts list:
  19. audioguru2

    200W kemokit-need help

    What is the amp doing when the resistors blow? Without a signal, the TDA2050 amps have a 60mA corrent drain. That is only 8mW in each resistor. With the amp at full output, the max voltage across each resistor is only about 1.2V, so each resistor dissipates only 655mW for half the time, so 1/2W...
  20. audioguru2

    How could I stop a nickel coil from emitting IR?

    Glow plugs for model engines are (were) available with different heat ranges. Ones that idled well had poor high speed performance and the other way around.
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