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    Speaker buzzing

    ok, I will open my monitor and take some photo..... before I throw it away.......... even it is still working......... :-X
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    Speaker buzzing

    haha...... ;D I have opened my poor monitor some months ago... since it got some strange color....... oh....... it is some loose connection between the PCB sockets and the cathode ray tube pins ........ I found that PCB, with high frequency components are all covered with a metal...
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    Relatively new, looking for some basic answers.

    A nice story.,..... it is practical but need big coils for induce enough power to drive home appliances........
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    Speaker buzzing

    As Ante said, nowadays monitors are properly shielded. It is hard to beleive the "buzz" is from the monitor. May be the jack of the speaker has been oxidized , try to clean it up.
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    LM78XX & LM79XX questions

    What I mean is both Ceramic capacitor and Electrolytic capacitors are worked together as a DC smoothing. You are right audioguru, 0.1uF Ceramic capacitors are as a low pass filter to shunt high frequency to ground while electrolyic capacitors are more like to handle the charge and discharge...
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    limiting line voltage...Optocoupler vs Zeiner...suggestions?

    I think is zener cannot handle the sudden goes up voltage and may fired the zener diode. I prefer to use opto-coupler as it totally isolated the high voltage part from your microprocessor.
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    LM78XX & LM79XX questions

    Those capacitors are used for smoothing the DC voltage from ripple. If the loading current is high, the ripple of the 78XX regulator will be higher.
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    Strange observation

    It is the matter of the "ON Load" and "OFF Load" voltage. They are normal.
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    wireless transmitter

    I built a single transistor AM transmitter which worked from 300MHz to 600MHz (adjust the capacitor across the L) which is used for digital data transmission. I am so lazy that I use the L in the LC tank to act like the antenna and make it as a track loop on the PCB. Actually, I have no choice...
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    wireless transmitter

    The LC oscillation transmitter will not be stable as it will easily affected when your hand approach it. (frequency drifted) And also, what will be the modulation is? AM? FM?
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    Simulation in Linux?

    I think a 486DX-66 with a lot of RAM can serve well as a web, ftp, mail and other servers if it is using Linux. :P Be honest, still, no Linux platform is as user-freindly as Microsoft does..... that is why I still using MS and pay some bucks to Bill Gates. Anyway.... back to the original...
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    Low cost RF transmitter

    Please give more details like: AM? FM? Transmit data? Audio? What is the data rate?
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    SAW filters

    Saw filter also applied widely in wireless products, it is nice with quite low attenuation. I also hear that a crystal can act like a filter..... I haven't tried myself.... any idea?
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    Beacon Finder Robot

    try to build an array of IR receivers to check the IR strength from the beacon.
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    Radioastronomy

    2.4GHz antenna..... not easy to build especially if used in transmitter. The feedback loss will drive you crazy...... if the impedance is not matched......
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    recorded voice player

    More to play with ISD IC, you can set the address pin and record say for example, 2 messages with 5seconds time; and also can play them back also. I have done this in a keychain recorder which serve very well. 8) Later I will give out a schematic how to do it and also some pictures of my...
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    3V LED Chaser project

    can I use astable transistors oscillator to give signal to the clock input to 74HC4017?
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    Pages take forever to load?

    I face this waiting also......
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    recorded voice player

    use ISD voice recorder IC. http://www.winbond-usa.com/products/isd_products/chipcorder/datasheets/1100/ISD1100.pdf
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    Beginers OPAMP question

    Thanks audioguru. That refreshes my old time memeory.... ;D One more question: if I got a sigal, say 1KHz, 2Vp-p with DC offset at 2Vdc; how can I use an opamp to adjust the DC offset to 1Vdc?
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