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  1. audioguru2

    3V LED Chaser project

    Its tolerance isn't marked and is probably 20%. The project's brightness will be affected if its value is near the end of its wide range. I always use 5% capacitors that cost only a couple of cents more, then I know their exact value.
  2. audioguru2

    frequency and voltage in DC motor

    I suspect that an ultra-slow LM358 is being used.
  3. audioguru2

    3V LED Chaser project

    Hi Nef, Welcome to our forum. ;D The ceramic capacitors do not have correct values are not suitable for this project. Also see my notes on the pic:
  4. audioguru2

    Speaker - frequency and impedance

    Speakers have a resonance frequency where the impedance is up to 5 times normal. The rated impedance of a speaker is at its lowest which occurs a little above its resonance frequency.
  5. audioguru2

    capcitive touch sensor

    Hi KSP, The circuit is capacitor-coupled to the live wire of the mains. Your body is grounded which is the other wire of the mains. Your finger, air in between and the sensor plate form a coupling capacitor to feed mains into the very high impedance circuit. The 1st transistor is an...
  6. audioguru2

    Transformer Winding Sequence Question

    Hi Kain, Philips ferrites website is at www.ferroxcube.com . I couldn't manage to search it. Litz wire is individually insulated strands of wire in parallel. I have never seen it for sale to hobbiests. Usually an IC maker like TI would have the circuit with a detailed parts list with suppliers...
  7. audioguru2

    frequency and voltage in DC motor

    Hi Duratia, Motors have inductance which limits current at high frequencies. PWM circuits have a max slew rate which limits output current at high frequencies. Attach your PWM circuit as a nice clear GIF or PNG file type and include part numbers for its transistors and ICs for us to see if they...
  8. audioguru2

    led problem

    Hi Rybitski, Welcome to our forum. ;D Does your transformer have a 12VDC output or an AC output? Without a rectifier, AC destroys LEDs. Your problem is that the LEDs in your circuit operate at more than their rated max of 30mA. Your "transformer", which is probably an AC to DC adapter is rated...
  9. audioguru2

    Speaker wire question

  10. audioguru2

    how to find out the frequency of an amplifier

    It is the capacitors in an amplifier that limits its low frequency response. Old amplifiers had transformers that also limited their low frequency response. A DC coupled amplifier amplifies very low frequencies and DC just as well as any other frequency. Calculate the reactance of the coupling...
  11. audioguru2

    Adams Motor Project

    It is majic or that awful music that makes it spin. ;D
  12. audioguru2

    Speaker wire question

    The speakers are both 4 ohms so will draw exactly the same amount of power no matter their size. I use 16AWG stranded wire for my speakers up to about 50 feet away. 18AWG is good for about 25 feet. I've seen and heard an 8 ohm speaker connected to hundreds of feet of 24AWG telephone cable, and...
  13. audioguru2

    pc Speed Test

    I had a peek at the huge file with the answer with 2 million digits following 3.14159......
  14. audioguru2

    pc Speed Test

    It's too bad my 486 100Mhz pc is broken. It would probably fly through the test. When I see my son again, I'll ask where he got the program.
  15. audioguru2

    pc Speed Test

    Yeah, my pc is 2.93GHz. Gateway says it doesn't have hyperthreading, but Intel says it does. It came with 512M of RAM. Its hard drive is 160GB and 7200RPM. It burns DVD's very well but I haven't tried dual-layer ones.
  16. audioguru2

    digital elec-stetho..

    Your 2nd filter stage is correct. ;D The bridge rectifier has an input connected to ground. Therefore it will short the 2nd filter's output when it tries to swing negative. The bridge rectifier isn't full-wave anyway without an inverted 2nd input. There isn't enough signal level for a passive...
  17. audioguru2

    pc Speed Test

    Hi Ante, Your laptop is fast. Faster than my pc. ;D
  18. audioguru2

    A vizz Appears on Telephone line when I connect the serial port!

    Hi Shahriar, Telephone lines are a balanced pair of wires. For audio, when one wire swings in a positive direction, the other wire swings equally in a negative direction. They are balanced to cancel mains hum and interference, that you hear when you connect to ground the wire that measures 0VDC...
  19. audioguru2

    Darlington Phototransistor - can i fudge one from an NPN phototransistor ??

    In "the good old days", there was a photoSCR that could do a remote strobe-flash, all by itself. I think it was made by GE.
  20. audioguru2

    pc Speed Test

    Hi Guys, I found a small program that calculates pi to umpteen decimal places of accuracy. My Pentium4-2.97GHz pc does its 2M selection (click on upper left corner to select) in 1 minute, 43 seconds. With Norton, my anti-spyware and everything else disabled, it took a few seconds longer. My pc's...
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