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  1. audioguru2

    Driving a HDD motor

    The low output voltage of the logic IC doesn't match the high gate threshold voltage of the Mosfet. Some might work. Some won't work. It is a poor selection of parts.
  2. audioguru2

    Transistor

    My transitter already has a preamp transistor. I showed a sim with it cutoff and not working with a supply voltage of only 2.5V. My transmitter is very sensitive to sounds. Adding another preamp would overload its input. I also simulated the "preamp" circuit you found and it saturates with...
  3. audioguru2

    Transistor

    I designed the biasing of the preamp transistor for a regulated 5V supply so it could have enough voltage gain. With a higher voltage then it is saturated. With only 2.5V then it is cutoff as my simulation shows:
  4. audioguru2

    sinewave trouble

    Kevin, you forgot to attach a schematic so I am just guessing. If you feed a triangle wave through a low value capacitor into a low resistance (a highpass filter), the high frequency harmonics are passed and the low frequency fundamental frequency is attenuated. It won't be a triangle waveform...
  5. audioguru2

    RC phase shift

    An RC circuit causes distortion if the source has difficulty driving the low reactance of the capacitor. It appears that a highpass RC filter causes distortion when it passes the high frequency distortion (harmonics) that are already present from the source and attenuates the fundamental frequency.
  6. audioguru2

    110v supply

    In large buildings under construction the electrical inspector turn on everything then takes infrared photos of the breaker panel. Hot spots are shown that later might cause a fire. An electrical wire has a small amount of resistance. Current in a resistance raises its temperature. Wire doesn't...
  7. audioguru2

    110v supply

    A fuse or a circuit breaker is supposed to pass its rated RMS current (the same heating power as DC). It will blow with a delay time according to the amount of overload. With a small amount of overload then the time will be long before it blows. With a high amount of overload then the time will...
  8. audioguru2

    NAD schematics urgently needed

    Google is also full of copies of copyrighted material. Google makes a profit. Off with Google's head!
  9. audioguru2

    Beat Controlled LEDs

    Hi Michael, I thought this is your project, not mine. I will help you if you run into problems. 1) Design a lowpass filter. 2) Design a peak detector circuit so that the LEDs light long enough to be seen. 3) Design an LED driver circuit. 4) Find suitable parts then make a parts list. 5) Design...
  10. audioguru2

    110v supply

    What are you talking about, Kevin? The transformer without a load is an inductor with an inductive reactance determined by the inductance and the frequency, not the peak voltage. The reactance is a very high resistance so the current is very small. A transformer is not supposed to saturate. It...
  11. audioguru2

    Problems with three wheel Driving Mechanism

    Hi Shaiq, Let the robot do a wheely then you don't need to steer it. ;D My car has front-wheel-drive. When it snows here in winter then the cars with old-fashioned rear-wheel-drive don't go anywhere because their back wheels don't have much weight on them so they spin on the snow and ice. This...
  12. audioguru2

    NAD schematics urgently needed

    We don't want the copyright police to come and shoot us or chop off our heads or whatever they do to copyright thieves. We copy the stuff just to look at it and to discuss it, so I don't think they will come after us for that.
  13. audioguru2

    Beat Controlled LEDs

    Blue LEDs are about 3.0V to 3.5V. Three can be connected in series and with a current-limiting resistor and connected to 12V. The current for each string of 3 LEDs is 25mA. A little transistor can drive up to 7 strings on and off and can be driven by an opamp lowpass filter for the bass.
  14. audioguru2

    110v supply

    Kevin, Take a length of wire and connect it directly to 110VAC. It will burn out or will blow the breaker. Then take the same length of the same wire and wrap it around a transformer's core, making the primary winding of a transformer. What happens when you connect it directly to 110VAC? Its...
  15. audioguru2

    Beat Controlled LEDs

    Hi Ani, The LM3915 has logarithmic steps for audio and light levels. Its steps are spaced 3dB apart so the range with 10 LEDs is 30dB. Two ICs can be cascaded for a 60dB range. The LM3914 has its 10 steps spaced 10% apart so it is a linear voltmeter. The LM3916 is an audio VU meter with...
  16. audioguru2

    circuits

    I don't think so. Twisted wires are very close together which makes higher stray capacitance between them. Adding capacitors increases capacitance. Stray capacitance is reduced by reducing the size of the circuit.
  17. audioguru2

    Beat Controlled LEDs

    You have described the LM3915 bar-graph LED display driver so why not use it? Its 10 outputs have constant current circuits.
  18. audioguru2

    transmission lines

    If the transmission line coax cable is 1/4 wavelemgth long then if its far end is open its close end will appear as a short.
  19. audioguru2

    opamps

    An opamp can have a non-inverting gain of 1. It has a high input impedance and a very low output impedance like these ones:
  20. audioguru2

    transmission lines

    Hi Ante, A short is zero ohms resistance to DC and is zero ohms impedance to AC. If the impedance of a transmission line matches its source and termination resistances then its length doesn't affect the impedance. A transmission line is many series inductors with many distributed bypass...
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