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  1. audioguru2

    interesting little project

    Hi Reuben, I had a room built onto the back of my house. I thought an electrical cover plate looked a little crooked, so I loosened it and straightened it. When I tightened the screw on the cover plate, it went into the live electrical wire in the box. The breaker didn't blow so I had quite a...
  2. audioguru2

    its been kind of .....DEAD lately...

    Hi Monster, Welcome to our forum. ;D You must be building this project: http://www.electronics-lab.com/projects/motor_light/026/index.html The author claims that it is an improvement on a 40 year old circuit that used germanium transistors. But he forgot that silicon transistors have an...
  3. audioguru2

    I need a datasheet for this car speaker

    It looks like an ordinary cheap car speaker. If you don't want to pay the manual people to see some "specs" that might not say what you need, you could measure its free-air resonance by feeding it through a 100 ohm resistor fron a sinewave generator. I betcha that it resonates at about 100Hz...
  4. audioguru2

    its been kind of .....DEAD lately...

    Hi ABJ, A 1 year long hangover? Were you still alive? ??? ??? I don't drink much anymore because I have so many things on the go. At Christmas I'll probably drink a little to get more of a smile on my face, but certainly not get drunk and regret it. I don't build things with tubes (valves)...
  5. audioguru2

    Question about Ground Loops

    Hi Walid, I've never built a an electrical substation nor a telephone system's central office. Most electronic circuits I work with and build don't need an earth ground. A few radios I built were connected to the electrical receptacle's ground, and very sensitive radios were connectd to my cold...
  6. audioguru2

    0-30 Vdc Stabilized Power Supply

    If you use 1 ohm for R7 then its max current will be about 2A, use 2 ohms then its max current will be about 1A, etc. With reduced current then its parts won't get as hot as with high current.
  7. audioguru2

    Input signal for LM3915. need help.

    Hi Ryeeson, Years ago I made this circuit and it worked very well. I am currently improving it. What kind of noise are you measuring, background noise or pink noise? Do you want to see the peak level to know if the amplifier is clipping when the random peaks all add, or see the average that you...
  8. audioguru2

    Mono sound triplexer

    Triplexer?? What do you want to do? Play the same mono sound through 3 speakers? Make a 3-way crossover network for woofer, midrange and tweeter speakers? Active or passive? Make a "color organ" where one light glows during bass sounds, a 2nd light glows during midrange sounds and a 3rd light...
  9. audioguru2

    using a2 astable multis to build a simple fm comm system

    What is the highest frequency that your two-transistor multivibrator oscillate? 200kHz? What will you do to get as high as 108MHz? That's 540 times higher. ;D
  10. audioguru2

    using a2 astable multis to build a simple fm comm system

    You want to re-invent the wheel? If you are talking about a two-transistor simple multivibrator, then how are you going to make it operate at a high enough frequency? How are you going to vary its frequency with a voltage? The antenna doesn't receive pulses. It receives a continuous high...
  11. audioguru2

    100W Audio Amplfier By Smart Kit

    The "how it works" section of the project explains its theory clearly. Read about how transistors work in our Articles section.
  12. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Shooter, 3A through a 0.47 ohm resistor will cause heating of 3 x 3 x 0.47= 4.23W. If it was 10% high at 0.517 ohms, it would heat with 4.65W. Sure it would be hot, enough to char the pcb or melt wire insulation since some power resistors are rated at 275 degrees C. You might have the...
  13. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Shooter, Welcome to our forum. ;D Your English is fine. I recommend the parts list posted a few replies ago. Some people built it like that and it works perfectly and is much more reliable. I am thinking about adding trimpots in series with the control pots so that the max voltage and current...
  14. audioguru2

    speaker to line level

  15. audioguru2

    digital elec-stetho..

    Hi Xoy, Isn't this a school project? Then make a simple circuit that rectifies the output of the Stethoscope project and drives a piezo beeper.
  16. audioguru2

    0-24V 4A bench supply

    Good! ;D Was the orange band on the resistors actually gold? (1 ohm) I think the switch and SCR would give an indication and protection if the load has an intermittent short. The buzzing is probably the transformer straining at full current.
  17. audioguru2

    pramplifier circuit

    Hi Mughal, If you are using a two-wire electret microphone, this circuit works very well and you can adjust its pot for the amount of gain:
  18. audioguru2

    Mosfet driver not outputing properly

    Horray, you fixed it! ;D
  19. audioguru2

    speaker to line level

    Why would SoundShark want to add an amplifier to his ordinary car radio? I think he is adding a powerful amplifier to his "14W per channel" radio. The 12V battery in a car limits the amplifier's power to 4W at clipping into 4 ohms for single-ended or 14W at clipping into 4 ohms for bridged...
  20. audioguru2

    speaker to line level

    A "headunit" is slang for a car radio with a CD player and maybe an MP3 player. Fairly new ones have two bridged stereo power amplifier ICs similar to the TDA1554 in our 22W project: http://www.electronics-lab.com/projects/audio/006/index.html that produces 22W per channel into 4 ohms at 10%...
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