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  1. audioguru2

    Lowpass filter for subwoofer

    FilterPro: http://www-s.ti.com/sc/techzip/slvc003.zip
  2. audioguru2

    newbie pot usage

    Hi, A 50K pot has a value far too high for an incandescent light bulb. Also, the pot is probably rated for only 1/2W over its entire resistive part. So when you turn it so that the lamp is half bright, only a tiny part of it must dissipate the same power as the lamp, burning it. To dim a lamp...
  3. audioguru2

    Coupling capacitors

    Kevin, A coupling cap with a value that is too low causes visual distortion to a square-wave or any other kind of waveform with sharp edges. It really isn't harmonic distortion, it is just the too-small coupling cap acting like a high-pass filter, passing the sharp edges but attenuating the...
  4. audioguru2

    Lowpass filter for subwoofer

    Hi Roby, That's a nice, powerful looking amp you have there. This sub-woofer low-pass filter project uses a Butterworth filter with a gradual slope of 12dB/octave. Many speakers need a sharper slope. You will also need its opposite, a high-pass filter for your main speakers. If you combine a...
  5. audioguru2

    Puggy Potty Alarm

    Hi CRE, Sure it's a joke!  ;D ;D If you drive the piezo transducer with a bridged audio amp like an MC34119, it will have 4 times the power. It will be so loud that your pug will stop what it is doing in mid-stream and be afraid to "mark" again. I used an MC34119 in my son's alarm clock and it...
  6. audioguru2

    Lowpass filter for subwoofer

    Hi Roby, I see, the pcb has more parts than the schematic: 1) Two 4.7uF/35V bypass caps in parallel with C2 and C6. 2) An LED (isn't it backwards?) and 1.5K current-limiting resistor at the positive supply. 3) Two 100nF caps paralleled to make the 0.2uF cap and a 180nF and 220nF caps paralleled...
  7. audioguru2

    Low Voltage Alarm?

    Oh No! It is one of our projects: http://www.electronics-lab.com/projects/sensors/023/
  8. audioguru2

    Low Voltage Alarm?

    Hi Guys, Here is a little test for you with a circuit that I found and it might even be one of our projects. What is wrong with it? Here is the project: http://www.aaroncake.net/circuits/lowvolt.htm Here is its schematic:
  9. audioguru2

    Lowpass filter for subwoofer

    Hi Roby, Aren't you talking about this circuit that doesn't have any 4.7/35V caps? Where's the LED? Here's the project's link again: http://www.electronics-lab.com/projects/audio/008/index.html The TL062 is lousy and the TL082 is noisy. I would use a low noise TL072.  I would like to know...
  10. audioguru2

    Piggy-backed PC power supplies?

    Hi Ante, Your DC to DC converters didn't have voltage sensing right at their outputs for feedback did they?
  11. audioguru2

    32768Hz quartz crystal sniffer circuit!

    Please attach the schematic or provide a link to the project or circuit so we know what you are talking about.
  12. audioguru2

    Lie Detctor

    You must figure out whether the resistors get hot all by themseves, or because of current flowing through them. If it is because of the current flow, a 1/4W resistor and a 1/2W one that have the same value will both have the same current and heat the same. Therefore if the power dissipated by a...
  13. audioguru2

    Lie Detctor

    The capacitor is used only to filter out local radio stations from being detected so just about any capacitor will be fine, 0.1uF, 1uF or anything in between. The project's battery is only 9V and there isn't any input voltage so just about any capacitor voltage rating will be fine, 16V, 50V or...
  14. audioguru2

    I'M Lost!

    Hi Ante, Rhonn's and my avitar are the only ones I see. All the rest are a small red x. I can look at anyone's profile including my own, but I can't make changes to mine just like your problem. I must be missing many new posts because the "More Recent Topics" isn't working anymore. 
  15. audioguru2

    Piggy-backed PC power supplies?

    Hi Ante, When the supplies have diodes or resistors in series with their outputs and the voltage sensing is connected to their combined output, I think the supply with the slightly highest voltage will handle most of the load. At full load its output voltage will drop enough for the lower...
  16. audioguru2

    Lie Detctor

    With an LED you won't be able to adjust the "zero" setting very well, won't be able to see small changes in skin resistance like a meter, and the LED will be very, very dim even when the test person is sweating buckets! Any small NPN transistor like a 2N3904 or 2N2222 will work with a meter in...
  17. audioguru2

    Power Supply problem

    Hi Sherbo, I didn't know that you used two paralleled transistors. You melted at least one of them, the one with the most gain. Transistors aren't all the same. Some have high gain and others lower gain. When paralleling transistors either you must measure and sort them so that their gain is...
  18. audioguru2

    Fm Transmitter help plz

    Hi Abs, What are you doing over here with the same question? Is the 11 minutes of operation from the 6V from a "9V" Ni-MH rechargeable battery good enough for your 4W transmitter?
  19. audioguru2

    Power Supply problem

    Hi Sherbo, Welcome to our forum. If you had 10A through your PNP transistor and 7V or more across it, you melted the poor thing. No wonder it leaks when not loaded.
  20. audioguru2

    Coupling capacitors

    No, the capacitor's output signal doesn't jump, and certainly not when the input signal stops changing. For high frequencies, the capacitor's impedance is low and its output follows its input. If the input suddenly changes its DC voltage, its output will follow then slowly charge or discharge to...
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