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  1. Audioguru

    Need help with this certain circuit (RC phase shift system)

    Why doesn't your "lecturer" teach you the basics of transistors?
  2. Audioguru

    Need help with this certain circuit (RC phase shift system)

    I changed a few things. Then the transistor probably will not work.
  3. Audioguru

    Solar power for extreme cheapskates

    Doesn't the weather produce cloudy days where you live? Then your solar power will be very low. Few daylight hours in winter?
  4. Audioguru

    High voltage: Can't stop electricity from jumping over resistors

    Name brand resistors have a datasheet that states and guarantees their voltage rating. Resistors made by somebody in their back yard have no guarantee.
  5. Audioguru

    1n4007 is getting hot

    If the diodes are smaller than normal then they are fakes.
  6. Audioguru

    I Need Help With My 555 Monostable Circuit Please

    On the other forum he said the timing capacitor is 470μF. Then the 51k timing resistor will cause the 555 to timeout in about 26 seconds If the battery voltage has not dropped too low.
  7. Audioguru

    Trying to power late grandmother's portable TV

    If the polarity is connected backwards, the TV, the power supply or both might blow up. If the power supply cannot supply the current (amps) required by the TV then the power supply might blow up or burn out.
  8. Audioguru

    Trying to power late grandmother's portable TV

    Even more important is the polarity of the plug. The TV shows that the pin is positive. Is the center part of the power supply plug also positive? Does the power supply provide enough current?
  9. Audioguru

    Need help with this certain circuit (RC phase shift system)

    Why do you have a 10uF capacitor at the 0V circuit ground at the bottom of the circuit connected to another "ground"? The output of the LM386 is missing the very important parts shown on the datasheet of the LM386 IC that prevent it from oscillating at a high frequency. The capacitor in series...
  10. Audioguru

    I Need Help With My 555 Monostable Circuit Please

    The values of R1 and C1 set the timing but your schematic does not say what they are. A 51k resistor with a 100μF capacitor produces about 5.6 seconds of timing. You say that you want timing to be "a period of time" but you do not say how much time. I think your weak little battery drops its...
  11. Audioguru

    9v Guitar Amp w/out LM386

    Tedstruck, you do not make any electronics sense. The battery in a car is only about 13.8V so they do not use 8 ohm speakers to get only 1.8W. They use 4 ohm speakers and bridged amplifiers. A bridged amplifier has one amplifier driving one wire of a speaker and another out-of-phase amplifier...
  12. Audioguru

    9v Guitar Amp w/out LM386

    I simulated it with the puny little low power 2N2222 and 2N2907 output transistors. The output level is less because the top of the output waveform is squashed causing distortion. I reduced the 160k to 100k for the bias resistor of Q3 and the bottom of the output waveform became clipped causing...
  13. Audioguru

    I Need Help With My 555 Monostable Circuit Please

    The monostable is a timer. It turns on when It is triggered then it turns off when it times out. If you want the motor to stay turned on after you momentarily push the button then remove C1.
  14. Audioguru

    LED headlight build

    The circuit does nothing more than one large resistor will do. It does not control the voltage, instead it simply reduces the current in the LED. If the forward voltage of the LED (it does not say) is 7V and the battery is 13.8V then The current is 80mA and the power in the LED is 0.56W. It will...
  15. Audioguru

    9v Guitar Amp w/out LM386

    The amplifier sounds awful because you forgot what I said in my post #38: "R5 TURNS OFF Q3!". Only very loud inputs turn on Q3 a little on the peaks. If R5 is removed then you do not need the first transistor but without the bootstrap capacitor there will be severe distortion as I showed in my...
  16. Audioguru

    Short Wave Radio Project Help Needed

    The very old circuit uses obsolete parts. It is missing almost everything in a real radio. Its selectivity is poor with only one LC tuned circuit (a real radio has at least 5 LC tuned circuits) so it might pickup 5 stations at the same time. It will be difficult to find a station because the...
  17. Audioguru

    Window comparator help (Battery monitor)

    The LM393 comparator has an output transistor that drives the output to ground with a low current (6mA max) but has nothing to drive the output positive. The 2N2222 reverse bias blinker needs at least 7V to work. Most circuits on the web use 12V.
  18. Audioguru

    I Need Help With My 555 Monostable Circuit Please

    The 9V battery and the 555 timer have low output currents. The motor might use a high current that will burn them out. The motor is not supposed to stay on, it turns off when the 555 timer tomes out.
  19. Audioguru

    Piezo Preamp EQ

    Your gain pot is messing up the tone controls, remove it. A piezo transducer makes a horrible microphone full of peaks at its resonant frequencies. Sometimes it is used in a drum or on the surface of a guitar.
  20. Audioguru

    I need help on how to use LEDs on this project

    A red LED is about 1.8V and a white or blue LED is about 3.2V. Then since the supply is 5V an LED connected directly parallel with the motor will instantly burn out. For 20mA use a resistor (5V - 1.8V)/20mA= 160 ohms in series with a red LED or a resistor (5V - 3.2V)/20mA= 90 ohms (use 91 ohms)...
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