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  1. audioguru2

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

    Hi Muffits, For a 5A output instead of 3A there are only a few changes to be made to the modified circuit: 1) 30VAC/7.1A transformer (212VA). 2) 15,000uF to 20,000uF for C1. 3) Three 2N3055 output transistors with emitter resistors. Very large heatsink or a fan. 4) 0.27 ohms/10W power resistor...
  2. audioguru2

    Surround Sound for car audio

    The Hafler opamp circuit should do what you want. The New Japan Radio IC datasheet doesn't explain what it does. It has graphs showing bass-frequencies-only, some phase-shift amounts and its block diagram shows a subtraction circuit for both channels but doesn't show what is subtracted.
  3. audioguru2

    0-30 Vdc Stabilized Power Supply

    The input of the opamp U2 is megohms so R9 doesn't affect how it works, until the current regulator U3 needs to quickly reduce the voltage at the input of U2. Then the resistance of R9 isolates C4 from the input of U2 so that D9 can quickly reduce the voltage at the input of U2 without waiting...
  4. audioguru2

    lesr from iraq i need help with 500w inverter

    The 4047 is electronic so doesn't make sound. Probably your transformer has loose laminations in its core that vibrate and make noise.
  5. audioguru2

    HELP - resistors and dip-switch

    If your fan sounds like a dentist's drill then the frequency of the 555 is too low and is audible. Reduce the value of its timing capacitor. Electric golf carts and wheelchairs don't make a whining noise because their PWM operates at a frequency above what you can hear.
  6. audioguru2

    Digital radar speedometer

    The AS and HC ICs are in the same case. The AS is much faster and operates at a much higher frequency than the HC.
  7. audioguru2

    HELP - resistors and dip-switch

    Doesn't the inductance of the motor reduce its max current at the higher frequency?
  8. audioguru2

    Simple help with transistors!!

    Your music player probably has a modern IR receiver IC. It doesn't even have a phototransistor. Where are you going to connect another phototransistor to it?
  9. audioguru2

    Simple help with transistors!!

  10. audioguru2

    HELP - resistors and dip-switch

    The circuit with only 3 parts has the Mosfet as a resistor and it gets hot. The Mosfet in a PWM circuit doesn't get hot. The difference in the cost of the parts is nearly nothing, but the simple circuit needs a big expensive heatsink.
  11. audioguru2

    DS1621 pc thermometer

  12. audioguru2

    Simple help with transistors!!

  13. audioguru2

    Simple help with transistors!!

    The datasheet for an IR receiver IC will have its max voltage and current ratings and have a typical receiving circuit. The TSOP series have the modulation frequency in their part number so you must match what your deck uses. the datasheet for an IR LED has its max current rating.
  14. audioguru2

    line in?line out?

    Nothing. It doesn't have an output for an external speaker. Connect the line out to the input of an audio amplifier and connect the speaker to the amplifier's output. Its line input of course.
  15. audioguru2

    Simple help with transistors!!

    Does an IR remote control work when it is outside in the sunshine?
  16. audioguru2

    line in?line out?

    A speaker is supposed to be connected to the output of an audio power amplifier, not a line level output. The line level output can connect to the input of an audio power amplifier. Connect the line level output of something to the line level input that you have.
  17. audioguru2

    HELP - resistors and dip-switch

    I have a permanent magnet electric motor operating its PWM at about 3kHz and it whines loudly. If your motor has a high inductance then a low frequency should be used. It takes time for current to build up in an inductor.
  18. audioguru2

    line in?line out?

    For audio signals, line level is between about 100mV to 300mV RMS. Microphone level is 2mV to 20mV and speaker level is a few volts to many volts. Components like a tuner, CD player or other sound signal circuit use line level to feed an amplifier. "Line in" is the line level input to an...
  19. audioguru2

    LASCR

    General Electric made a light activated SCR 40 years ago. They don't make it anymore. Another electronics company might make one and have spec's for it.
  20. audioguru2

    HELP - resistors and dip-switch

    Changing the DC voltage of pin 5 on a 555 changes both the frequency and the duty-cycle of the pulses. Using the steering diodes circuit or the triangle-wave circuit changes the duty-cycle of the pulses without changing the frequency much. Then the frequency can be high enough that it isn't audible.
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