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  1. audioguru2

    Vocal Remover Circuit

    Stereo is recorded on 2 channels and surround sound uses 4 or 5 channels. There are some Oriental ICs that produce fake surround sound when the input is ordinary stereo. Some people think it sounds real. 
  2. audioguru2

    0-30 volt stailized power supply

    Many power supplies use a fan blowing past the heatsink so that the heatsink can be smaller.
  3. audioguru2

    0-30 volt stailized power supply

    Your 0.33 ohm resistor R7 with 2A in it has a voltage across it of 0.33 x 2= 0.66V. The current-setting circuit in the 30V/3A power supply has 0.47 ohms x 3A= 1.41V across it. Your current-setting circuit needs to be calculated to show 2A when its pot is set near maximum. Only one R7 is used...
  4. audioguru2

    0-30 volt stailized power supply

    R7 has nothing to do with the output transistors. Instead R7 senses the amount of output current and sends its sensing voltage to the current adjustment opamp. Each of your output transistors need a series 0.33 ohm emitter resistor so that the two transistors are better matched to share the...
  5. audioguru2

    0-30 volt stailized power supply

    The parallel transistors in the circuit you posted do not have series emitter resistors so the ones with high gain take a high current and the ones with a low gain take a low current. Emitter resistors help to match the transistors. This is how the output transistors are connected in parallel:
  6. audioguru2

    Can ULN2003 drive two 6~9V DC motors?

    The datasheet of the ULN2003 shows that the saturation voltage loss is 1.4V. Then if the battery is 3.7v the motor gets only 2.3v but if the battery is 7.4V then the motor gets 6V. You did not say how much voltage and current the motor needs. You did not say what is the stalled current of the...
  7. audioguru2

    0-30 volt stailized power supply

    The very old circuit you posted works poorly. TR3 is its output transistor and it gets too hot. Add a second 2N3055 transistor parallel with TR3 to share the heat and add a 0.33 ohms/2W resistor in series with each emitter to the output. The transistors collectors can be connected directly...
  8. audioguru2

    0-30 volt stailized power supply

    Sorry, I was wrong, you are correct. The peak of 24V RMS is 33.9V not 40V. The peak of the 28V RMS transformer I recommended is 40V. Then the full load drops the rectified voltage to 38VDC with ripple and the losses in the circuit have enough extra voltage for the output to be well-regulated...
  9. audioguru2

    0-30 volt stailized power supply

    If the transformer is rated at 24VAC/2A then it provides a maximum power of 24V x 2A= 48VA. But if the output is 30V at 2.0A then the load uses 30V x 2A= 60VA plus heating power. The peak of 24VAC is 40V which feeds the bridge rectifier which charges the main filter capacitor to the peak...
  10. audioguru2

    ICL7107 ammeter

    Use a separate +5V supply to power the voltage meter and current meter. Connect the grounds of both meters to the (-) output of the power supply being measured. The current meter can measure the negative voltage across the 0.47 ohms R7 of the power supply being measured, then the current meter...
  11. audioguru2

    Need help with using a transistor or triac as a switch

    Your simulation is cheating because it uses a very high base voltage that has almost unlimited current and no voltage drop.
  12. audioguru2

    Need help with using a transistor or triac as a switch

    Same question again but on this forum. Here you forgot to say which relay you will use so we do not know its coil current then we cannot calculate how much input current a transistor needs. You also did not say how much current the 1.2V timer can produce which might not be enough current to...
  13. audioguru2

    0-30V 0-3A Latest Data

    The 24VAC transformer probably produces 25VAC with a light load on the project. Then its rectified and filtered output is +34V and -5.6V which power the opamps. At times the voltages are higher. Your transformer will be overloaded if its power rating is 105VA or less (24V at 4.4A).. The old...
  14. audioguru2

    Need Heaphone/Mic Amp Circuitry

    Software will not test the frequency response of a mic. You need calibrated sounds at different frequencies to do it. the manufacturer should have shown a frequency response graph like these ones:
  15. audioguru2

    Need Heaphone/Mic Amp Circuitry

    A frequency response spec must include how much the levels deviate. Plus and minus 30dB is horrible but 2dB is pretty good. If they do not spec the plus and minus dBs then assume it is horrible.  If you have background noise then you can turn down the volume. Using filters to cut frequencies...
  16. audioguru2

    Need Heaphone/Mic Amp Circuitry

    Why do you want to reduce frequencies below 20Hz and above 20kHz? Audio signals do not produce those frequencies. If the filters are for the microphone then the microphone probably will not produce much below 20Hz and above 20kHz. 
  17. audioguru2

    HELP with Schematics for magnet launcher

    We told you on all the other websites: Since you cannot read the simple schematic and do not know what connects to what then you probably have parts with the wrong values and ratings. Don't make this dangerous project.
  18. audioguru2

    Help getting started: battery powered record player.

    Crosley still make record players. I found one in the trash that was probably wrecked by someone using the wrong polarity 9VDC adapter. it has a full range mono 6" speaker in it. it has an Aux output to feed an external amplifier if you want. A car amplifier runs from 12VDC...
  19. audioguru2

    heathkit IT-11 capacitor checker

    Is it so old that it has one of those old glass vacuum tube thingies?
  20. audioguru2

    Need Heaphone/Mic Amp Circuitry

    Most of the spec's for the headphones are absolutely useless. The frequency response spec's do not say plus and minus 30dB which is horrible or plus and minus 2dB which is pretty good. Who cares about the length of the cord and the weight? The important spec for the ear speakers is the...
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