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  1. audioguru2

    about mixer

    Crosstalk from another input, interference, mains hum or other "stray pickup". Audio amplifier stages are usually biased so that their output can swing equally positive and negative from the DC biasing level that it has without input for max undistorted output level. An audio mixer is used to...
  2. audioguru2

    audioguru fm transmitter

    I made my coils like this:
  3. audioguru2

    RMS

    When audio amps or speakers are rated in phoney power I call it Whats instead of Watts. Most IC amps are rated at 10% distortion where the output is heavily into clipping, since with an output level just below clipping the distortion is very low. TI rate the power of their Class-D amp ICs with...
  4. audioguru2

    low current transistor bias

    With a 300 ohm collector resistor and only 1mA of collector current then the transistor is nearly cutoff and is not a linear amplifier. It mifgt be used to amplify a pulse that turns it on more. A bipolar transistor has fairly low distortion when its base is driven with variable current. If it...
  5. audioguru2

    RMS

    RMS power does the same amount of heating in a resistor as DC power. "Peak" power is measured with square waves where the output of the amplifier is clipping very badly (producing horrible distortion) and therefore its peak voltage is 1.414 times its RMS voltage which causes its peak current to...
  6. audioguru2

    Ante 50 Years Young

    I hope you have a Very Happy Birthday, Ante. ;D ;D
  7. audioguru2

    Lowpass filter for subwoofer

    Frt, This project's schematic, its parts list, its pcb layout and its photo don't agree with each other. It would be a fairly big job to sort it all out. We don't even know if it works. Similar projects are on the web and are presented more clearly and are fully completed.
  8. audioguru2

    low current transistor bias

    What is 1mA, the transistor's collector current or its base bias current? Please sketch the transistor's circuit. If it was a small power transistor as a common-emitter stage without an emitter resistor, with a current gain of 40, a 24V supply and its operating point at 12V for its collector...
  9. audioguru2

    Help me to explain the LM3915 operation.

    Since the ouput pins are connected directly to the LEDs and the forward voltage of an LED is about 2V, then the output voltage can't go down to a logic low voltage of about 0.5V, but is about 3.0V when the circuit has a 5V supply. The datasheet shows how a PNP transistor can detect current in an...
  10. audioguru2

    amplify the power (infrared)

    Doubling the number of IR LEDs won't make much difference when the receiver circuit results in such a high loss instead of a high gain.
  11. audioguru2

    amplify the power (infrared)

    I already told you that the LM324 is lousy and showed a graph from its datasheet. I also said that the TL07x family of opamps performs well up to 100kHz. The TL07x family of opamps is low noise, low distortion, wideband and inexpensive. Here is how the opamps compare:
  12. audioguru2

    low current transistor bias

    Please attach the circuit's schematic so we can see what you are talking about. No. The AC gain of a common emitter transistor amplifier stage is determined by the ratio of its collector load impedance to its emitter resistance, not its bias current. A transistor's DC gain is actually a little...
  13. audioguru2

    Plants wattering watcher

    The project uses a very low AC current between the probes.
  14. audioguru2

    Bootstrap Circuit

    I got this link from Google: http://www.linear.com/company/software.jsp
  15. audioguru2

    amplify the power (infrared)

    Provide a high resistor value for the phototransistor's collector resistor, a high impedance load for it from the high frequency opamp's input impedance and more gain from the opamp. Then the range will be plenty with your two IR LEDs.
  16. audioguru2

    Thermister Controlled Fan??

    I don't think that a little 0.8W fan will cool the engine enough. A model airplane has the propeller and movement through the air blowing on the engine to cool it and the power of the airflow is much more than possible from a little 0.8W fan.
  17. audioguru2

    Help me to explain the LM3915 operation.

    Hi Ryeeson, It uses controlled LED drive current from the comparators so that the output transistors supply a constant current to the LEDs, so that current-limiting resistors aren't needed. The output transistors don't saturate, they operate as variable resistors. Look at how constant is the...
  18. audioguru2

    10 A FET

    Hi Prateek, An incandescent light bulb's filament operates at thousands of degrees so its resistance is increased by the temperature. When cold, the filament's resistance is about 1/10th its hot resistance and therefore its turn-on current is about 10 times its hot operating current. There are...
  19. audioguru2

    Bootstrap Circuit

  20. audioguru2

    500W 12v to 220v Inverter

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