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  1. audioguru2

    i need help extending the keys finder project. can someone help me out????

    Hi Logan, I have my daughter's old cell phone that was run over by a few hundred cars. I used its small electret mic in my FM transmitter, and now it is in my Sound Level Indicator project. It has a thin soft rubber sleeve around it. Guess what? "You" logged onto MSN just now so I started...
  2. audioguru2

    If I want to put a switch on the AC current...?

    If you are in North America then use a switch rated for the mains voltage and whatever current your circuit will have at max. Switch the mains hot wire if the plug is polarized. For a few cents more you can get a two-pole switch to switch both wires which is safer.
  3. audioguru2

    DC Motors

    An LM317 is rated at 1.0A to 1.5A in a TO-220 case that can be bolted to a heatsink. Since the samples you ordered from TI are rated at only 500mA then they are probably in a tiny surface-mount case that can't be fastened to a heatsink. If your morors draw enough current that the LM317s need...
  4. audioguru2

    i want an idea!!!!! please help me

    No problem, now you are discussing circuits. National Semi explained its function in their applications note for their LM380: "Since a speaker is an inductor, its impedance is high at high frequencies. The amplifier oscillates at a very high frequency without a load so the 2.7 ohm resistor is...
  5. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    A CPU heatsink is much too small to dissipate 121W.
  6. audioguru2

    help!! AD595 Project

    When the AD595 circuit gives more than 200mV when it measures more than 20 degrees C then just use a simple two-resistors voltage divider at the input of the meter for it to read higher voltages.
  7. audioguru2

    i want an idea!!!!! please help me

    Isn't this forum "Electronic Projects Design/Ideas" supposed to be for people to discuss project design ideas, not just ask for ideas? Shaiq, you had good ideas before and we helped you with them. Find another good idea and we'll help you with it again. Look at the many power amps in our...
  8. audioguru2

    confusing battery

    When I was a kid in about 1956, my uncle gave me my very 1st portable radio that used a center-tapped battery with 3 terminals. That battery is still sold in Sweden???
  9. audioguru2

    confusing battery

    The 3rd terminal is spare and is used if one of the real terminals wears out?
  10. audioguru2

    confusing battery

    What is the 3rd terminal connected to in a Tudor battery?
  11. audioguru2

    Op amp theory Q's

    That's why I use ordinary audio opamps, then I don't worry about instability and don't need to use RF construction methods. Without adding noise gain, then my circuits have the low distortion provided by full negative feedback and are quiet. I think using an opamp for audio that has full output...
  12. audioguru2

    Problems lately accessing this site

    Today about 7 hours ago this site gave access problems to me and to Logan on the other side of earth. A few times I got "Server cannot be found" and a few times a reply button didn't work or the background of the main page loaded then a very long delay. One time the main page loaded with an...
  13. audioguru2

    0-30 Vdc Stabilized Power Supply

    The LF356N also has an unusual offset adj. voltage and its max supply is only 36V. Look at www.datasheetarchive.com for more.
  14. audioguru2

    Vectorbord or Veraboard

    It is nice to see it is fiberglass and is perforated, and is nice and big. But it certainly isn't Veroboard, that has half a circuit's wiring already etched into strips. I used to buy fiberglass Veroboard about that size, but can't find it anymore.
  15. audioguru2

    DC Motors

    Hi Siddarth, There are many transistors with the same or better spec's than the old one used in the datasheet. If overheating isn't a problem then you could use the LM350 for 3A or the LM338 for 5A without a booster transistor. Voltage regulator ICs each have a slightly different output...
  16. audioguru2

    help!! AD595 Project

    Hi Avionic, The AD595 already has an opamp for its output so why add another? Just connect its pins 8 and 9 for an output that is 10mV/degree C. The load should be a high resistance to prevent the IC from heating.
  17. audioguru2

    Op amp theory Q's

    Hi Indulis, Those resistors from the inverting input to ground are used to make unstable opamps more stable, by adding "noise gain". I use stable opamps so have never used them. Opamps with ridiculously high operating frequencies are made with inadequate compensation capacitors, so they...
  18. audioguru2

    i need help extending the keys finder project. can someone help me out????

    This site is intermittent again. Let's continue on MSN.
  19. audioguru2

    i need help extending the keys finder project. can someone help me out????

    Hi Logan, If you ground pin 5 or pin 9, the beeper should beep at 8 Hz.
  20. audioguru2

    Op amp theory Q's

    Hi TG, There is your problem. You were using an OPA637 opamp that has full output at the top of the AM radio band! In order for it to go so high, its design causes it to oscillate with a gain of less than 5. Its high frequency response is so good (?) that in a non-inverting situation the pcb's...
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