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  1. audioguru2

    6 or 7KW Inverter Needed

    Hi Renaldo, The 2kW sine-wave inverter article is a good one. ;D
  2. audioguru2

    Help Needed Calculating Resistance

    That was the 1st schematic I drew on a pc. On my old 486 pc. i didn't know that JPG schematic files look so baaaaad. ;D
  3. audioguru2

    CRITISIZE THESE CIRCUITS

    Sorry Musty, I haven't played with counter ICs for ages. Maybe someone else can help.
  4. audioguru2

    Millipede project question

    The cell phone vibrator motor I have is about 2/3 the size of that one.
  5. audioguru2

    Input signal for LM3915. need help.

  6. audioguru2

    Transformer and LM317 Question

    Hi Harry, Please convert schematics to a GIF or PNG file type on your hard drive the attach them directly to your post or reply. JPG file type is used for photos and appears fuzzy with schematics. Your file storage ImageShack server is usually to busy to work. An LM317 can be a current...
  7. audioguru2

    Best circuit drawing software out there?

    Microsoft Paint does eveything I need to make schematics.
  8. audioguru2

    Millipede project question

    Hi Js, A pager motor swings a little weight around and is used as the vibrator alert in a wireless pager or cell phone. I have one from my daughter's cell phone that got run over by a few hundred cars. I salvaged its tiny electret microphone and I looked at the "pager motor" for a long time...
  9. audioguru2

    Resistance wattage in series

    Hi Prateek, When resistors in series have the same value, their power rating is simply added. Why use recipricals?
  10. audioguru2

    Low-pass Filter?

    Hi Ren, The modified 500W inverter is used in the Philippines to power fluorescent lights and TVs that work with an input from 85V to 250VAC. If you used many paralleled batteries, an enormous transformer, 8 to 10 times as many transistors, 8 to 10 times the size of the heatsinks and a few other...
  11. audioguru2

    6 or 7KW Inverter Needed

    Inverters are about 85% efficient. Therefore to make an output of 7kW the battery power must be 8.24kW. Somehow, you must get rid of 1240W of heat. If you could find an extremely high-power 12V battery then it must produce a whopping 687A continuously. Most batteries and alternators would...
  12. audioguru2

    American DJ Pocket Scan

    I've repaired many intermittent problems just by unplugging circuit boards, connectors and ICs if they have sockets then re-seating them a few times.
  13. audioguru2

    FM Radio

    Your capacitors are fine. The little ceramic ones must be ceramic. Humming indicates mains interference pickup. Maybe the wires in your circuit are too long. Radio circuits won't work on a breadboard because the long wires and rows of connections have too much stray capacidance and inductance...
  14. audioguru2

    yagi antenna

    Go to www.google.com and in the search box enter FM Yagi Antenna, and then later enter FM RF Preamp.
  15. audioguru2

    op-amp low frequency pulse generator

    I agree with your explanation and your math. Why does this site mess-up certain English symbols? I see a lot of open squares in your text, and in the text of my projects. My extremely low distortion sine-wave generator uses a CD4018 Johnson Counter as a DAC to make a stepped sine-wave with very...
  16. audioguru2

    op-amp low frequency pulse generator

    Here's a sketch:
  17. audioguru2

    Resistance wattage in series

    Of course the wattage of the resistors is doubled when they are in series. Two 240 ohm resistors are 480 ohms. Put 22V across both in series and the total dissipation is 1W which is divided between the resistors because their value is the same. Therefore two 240 ohm half-watt resistors in series...
  18. audioguru2

    Resistance wattage in series

    The 18k capacitor discharges the 10uF capacitor in 180ms, reducing damage to the LED when its voltage is reversed when the power is turned off. The absolute max reverse voltage for most LEDs is only 5V, and this circuit has 9V. I never operate parts beyond their max ratings so I don't know how...
  19. audioguru2

    Help Needed Calculating Resistance

    With a 9V battery and a 2V red LED, 5k reduces the current to a very low 1.4mA. My new Sound Level Indicator project operates its 1.8V red LEDs at 26mA and they are blinding. Its brightness switch reduces their current to only 2mA and I still get complaints from my wifey that it is too bright. :'(
  20. audioguru2

    op-amp low frequency pulse generator

    Indulis, I understand that a transient contains high frequencies and that the reactance of a capacitor is low (like an AC short) a high frequencies. It isn't a DC short. I don't understand how an inductor can be "open" when fed from a DC current source. An inductor resists the flow of high...
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