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Shahriar

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Posts posted by Shahriar

  1. Hi

    Imagine you want to build a Laboatory System which has a common Shield cable through all Sets.The system should have the capability of talking persons to each other seperately. I mean in the following System with 4 Sets, Person No.1 wants to talk to No.3 and No.4 Wants to talk to No.2 without Interfering their sounds. how is this possible?

    My plan is Mic Amplifier No.1 & No.3 should Modulate their signal in a seperate Frequency (i.e. 1Mhz) and the same for No.2 & No.4 (i.e. 1.1Mhz)

    ThanX
    Shahriar

    post-1483-14279142633199_thumb.jpg

  2. Thank you very much.

    Don't you know that if experts can overcome this problem by Digital Sound processing Tricks?
    To examin this I conected my Mic to my Sound Card and then Increase the Speaker Volume. The same thing happened to it too. But I am Not sure if my Sound card is Based On Digital Sound Processing....  ::)

    By the Way, Does Omni directional Microphones Solve this Problem?

    Shahriar

  3. Hi

    I have built a PreAmplifier and a Power-Amplifier and it works Very good

    when I coonect my PC output to it.
    When I connect My Electric Mic to it

    and Increase the volume, a Sound Like a horn appears On the Loud

    speaker.This also happen when mic is Close to LoudSpeaker.

    Let me tell My Oponion about the reason and you tell me if I think right

    or not.

    The Mic take a harmonic and this Harmonic will be apmlified by PreAmp and

    PA. When This harmonic comes out of the Loud Speaker the Mic takes it

    again and the cycle Begins oNce more so an Oscillation occures and we

    hear that like a horn Sound.

    What should we do to solve this problem?

    ThanX in Advance
    Shahriar

  4. Dear gogo
    Thank you for your reply!

    I asked the same question from a FPGA Expert that I found his email in his website http://www.fpga4fun.com

    This is what he asnwered:

    Use a MCU when you need to do something once in a while, use an FPGA
    when you must do something continuously.

    For example, doing an Ethernet packet analyzer can be done with a MCU,
    since you receive packets once in a while. But doing the Ethernet
    physical receiver needs to be done in hardware (FPGA), since the
    receiver is actually the piece of hardware that continuously listens
    to the wires to see if a packet is coming.

    Hope that's (kind of) clear.
    Jean

  5. Hi,

    My question is:

    when should the project use a microcontroller, or when should it uses FPGA? Can you provide a good example of the project. The project that comes to my mind are:
                a.  A pong game using LCD interface and push buttons.
                b.  A stepper motor controller that will control 2-3 motors
                c.  A simple version of Atari game console
                d. An oscilloscope
                e. A project that involve image processing from camera input
    At first I thought that from a hobbiest, that they will make it in microcontroller but in industry they will do it using FPGA. But after further thought, since the cost of FPGA is more that a simple microcontroller, this is not making sense.

    Thank you,

    Shahriar

  6. Hi

    I have built a device which shows Caller ID on PC via Serial port.
    that works properly, but the problem is that when as soon as I connect the serial port to my device
    a Vizz(bad sound) apears on telephone. the serial port has the same GND with telephone line and other pins
    of serial port goes directly to RS232 IC.

    What is the reference of this Parasit and how can i Solve it!

    Thanks in advance
    Shahriar

  7. Dear indulis

    I know that LM317 can not Handle 15A. I send that schematic to show how my circuit is going to charge that battery.

    INSTEAD OF that LM317, I want to use a PC ATX Power supply. Just to limit the current I want to pull Up the stand By pin PC Power supply. The Only thing I want to know is That: "" Is it possible to limit current at 15A By pulling up the Stand By Pin Of an ATX Power Supply, Or that ATX will turn on and Off repeatedly??? ""

    Sorry to say this, But I am writing the same sentences as I have written in my previous Post....  ??? ??? ???


    ThanX
    Shahriar

  8. In TV reapiring, there are some problems that will beOkay a few minutes after the TV works. i.e. there is no Ruster,, {after few minutes, it appears.} it is alwasy beacuse of an Electrolit Cap. Bad Caps when get hot start working properly, but when they are cold, Some of their specifications Differs...

    I should say that this happen mostly in those caps that get charge and discharge repeatedly

    HTH - Shahriar

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