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  1. Audioguru

    Simple resistor overheat problem

    But 55 Ohms is not a standard resistor value anyway. Maybe it should be 56Ω?
  2. Audioguru

    Simple resistor overheat problem

    But 55 Ohms is not a standard resistor value anyway. Maybe it should be 56Ω? Then the current with a brand new 9V battery will be about 102mA (plus or minus the forward voltage range) into the LED that has the lowest forward voltage and it will fail quickly. Unless the LEDs have their forward...
  3. Audioguru

    NPN circuit isn't switching after power change

    A 2N2907 is described and shown as a PNP on its datasheet.
  4. Audioguru

    12vdc low amp to 120vac high amp flash/blink lamp inverter circuit?

    I agree that the flashing light bulb will not last long. it might last longer if you keep it warm with some current between flashes.
  5. Audioguru

    Modifying AGC circuit

    How about a bridged car amplifier? It uses a single supply and has both amplifiers biased at half the supply voltage. The speaker gets AC and its wires do not swing above and below ground even without a coupling capacitor.
  6. Audioguru

    5 PCs sound to 1 speaker with common GND

    You show a stereo jack that disconnects two unbalanced (not bridged) stereo loads and connects the two new stereo loads that are plugged in. There is no third pole to switch on an LED.
  7. Audioguru

    Simple resistor overheat problem

    I did not see the symbol for Ohm:
  8. Audioguru

    Modifying AGC circuit

    Ceramic caps are not used for low level coupling: 1) They are microphonic and might cause noises or acoustical feedback. 2) They cause low frequency distortion because their value changes when the signal voltage changes, then they pass half the low frequency waveform but attenuate the other half...
  9. Audioguru

    5 PCs sound to 1 speaker with common GND

    If the amplifiers are "bridged" then each of the two wires for a speaker is driven by its own amplifier and if you "common them together" then you are shorting the amplifiers. A shorted amplifier usually becomes destroyed. If you connect the outputs of two or more amplifiers together then they...
  10. Audioguru

    Modifying AGC circuit

    An OPA134 (a dual is an OPA2134 and is used for stereo) is made for audio and is excellent:
  11. Audioguru

    If I have a Li-Po battery connected to four quadricopter motors...

    My quadcopter hovers pretty well because its heaviest part, the battery, is on the bottom so gravity keeps it stable unless I control its direction.
  12. Audioguru

    Voltage Follower Doesn't Work

    The circuit for most amplifiers always has a ground.
  13. Audioguru

    If I have a Li-Po battery connected to four quadricopter motors...

    Buy a quadcopter and look inside to see how it is made. It has a custom IC that is a microcontroller with a memory and a program stored in it. Frequently a quadcopter has gyroscopes for stability and uses a GPS device for its location. We solder wires together, we do not tape them.
  14. Audioguru

    Modifying AGC circuit

    The lousy old dual opamos in an LM358 and its sister the quad opamps in an LM324 are no good for audio: 1) They are low power so are missiog enough bias current therefore they produce crossover distortion. 2) They are noisy (hiss). 3) They have trouble with high level frequencies above only 2kHz.
  15. Audioguru

    Voltage Follower Doesn't Work

    An electronic circuit needs to have a power supply with a low impedance. The internal resistance of a battery increases as its voltage runs down then the supply is not a low impedance unless there is a parallel capacitor.
  16. Audioguru

    If I have a Li-Po battery connected to four quadricopter motors...

    Simply read about pulse-width-modulation in Google. Most radio controlled models use PWM for motor speed control and full size cars, trucks and buses use PWM for LED dimming.
  17. Audioguru

    JVC Speaker getting power but not producing sound

    9V/8 ohm= 1.125A but the voltage of a new little 9V alkaline battery with a current that high will probably drop to 6V or less. 6V squared/8 ohms= only 4.5W that most speakers can survive (but maybe not a tweeter).
  18. Audioguru

    Building switch between PC headphones and PC speakers. Can I combine the Grounds?

    All the powered pc speakers I have seen have a 3.5mm stereo headphones jack that is already attenuated and when headphones or an aux cable is plugged in the speakers are switched off. I do not know why your pc speakers do not have a headphones jack and I do not know if the speaker amplifiers...
  19. Audioguru

    Voltage Follower Doesn't Work

    In addition to the minimum supply is 10V, the datasheet for the old LF353 shows that the inputs do not work if they are within about 2.5V from the negative supply that is 0V in your circuit. Therefore the opamp does not work properly unless the input is +2.5V or higher in your circuit if it has...
  20. Audioguru

    What is the real name of this part?

    D16 and D17 are producing clipping because the input signal level is too high. Turn down the input level to prevent the clipping. The schematic shows 33 milli-volts (0.033V) but the output of the opamps are much higher.
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