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  1. audioguru2

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

    Here is another applications note about the voltage input vs the voltage output of ordinary Cmos logic that is applicable to using inverters as linear amplifiers. The ouput Mosfets are perfectly symmetrical: AN-90.pdf
  2. audioguru2

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

    My 1st graph shows that a CD4069 or 74C04 inverter with a 3V supply and a high resistance as a negative feedback resistor and a low resistance as its inverting input resistor has a voltage gain of about 500 at low frequencies. The Whistle Responder mic preamp can't have a low value for its input...
  3. audioguru2

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

    Hi logan, I have used the CD4069 as a linear amplifier many times and it works well. RCA had an appl. note which is also in National's AN-88 applications note about their 74C04, which is the same as the CD4069. The CD4069 is completely symmetrical, so operates very well as a linear amplifier...
  4. audioguru2

    quick question

    What signal, voltage or current are you switching? A CD4053 has three SPDT switches and can switch at a pretty high speed. It is for fairly low current signals.
  5. audioguru2

    Negative Voltage Rail Sag

    Hi Mr. Heckles, Your top two 4558 ICs are straining with a high current into their low-value negative feedback resistors. The output resistance of the ICL7660 is about 45 ohms, so 20mA into the 4558s creates a 0.9V drop. An application note for the ICL7660 shows a voltage regulator with one. I...
  6. audioguru2

    0-30 Vdc Stabilized Power Supply

    MP, I am not arrogant! Mixos, the owner of this site built this project and got together with Staigen, our expert power supply member. They reported the problems that Mixos had with his project in the topic about modifying it for a 5A output. The problems that Mixos had are the same problems...
  7. audioguru2

    Small Cap between OpAmp Input Pins?

    I think the small valued cap stops problems caused by radio or TV pickup.
  8. audioguru2

    3uH Inductor at the output of PowerAmplifier?

    Hi Shahriar, Many power amplifiers oscillate with a capacitive load. A speaker system is capacitive on one side of its main resonance or at a higher frequency resonance. The inductor isolates a capacitive load at very high frequencies.
  9. audioguru2

    Op-Amp with a load resistor..Plz help

    Hi Shaiq, Your circuit doesn't need R3 and R4. Connect the output to R2. If the load resistance is high enough that the opamp can drive it, then the voltage gain isn't affected by it. When the opamp's output begins to drop, the negative feedback is reduced by about the same amount, then the...
  10. audioguru2

    why no UV communication system?

    UV emitting LEDs are luckily low powered, so don't go very far. It is lucky that they are low powered because UV causes eye and skin damage. Its wavelength is approaching x-rays.
  11. audioguru2

    0-30 Vdc Stabilized Power Supply

    I bet it doesn't produce a regulated 30V at 3A. Probably only 2.5A at 26V with lots of ripple like many of the complaints. It is rated for zero volts to 30V at 3A, so it shouldn't melt over that range.
  12. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Mix, Welcome to our forum. ;D When the project's output is shorted or set to a low voltage at 3A. Q2 has about 32V across it and up to 100mA through it. That is heating of 3.2W. A little 2N2218A will be at its absolute max internal temperature with about only 1.5W with the clip-on tiny...
  13. audioguru2

    DC Motors

    The tiny little regulators you ordered will probably over-heat and shutdown.
  14. audioguru2

    Hex Non-Inverting Buffer

    Hi Gogo, Your pic is too big, I reduced it. The output voltage and current of the PIC is much more than the CD4050 and is more than enough to drive the darlington transistors. It can be replaced by four 560 ohm resistors.
  15. audioguru2

    how to design a remote control????

    Hi Shaiq, Using radio for remote control is expensive and complicated but gives long range. Using infrared is easier but is line-of-site and diecrional and has a short range. Google has many discussions about RC which is Radio Control for models.
  16. audioguru2

    Op amp theory Q's

    Hi again, TG. I forgot. Your addition of noise-gain increases the level of noise and distortion so it becomes audible:
  17. audioguru2

    Op amp theory Q's

    Hi TG, The OPA2134 is an excellent audio opamp but isn't much better than a TL072. Its power bandwidth is 230kHz, not 8MHz. The power bandwidth of a TL072 is 100kHz. An opamp's output is slew-rate-limited above its max power bandwidth but still has gain up to its gain-bandwidth-product (GBP)...
  18. audioguru2

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

    Don't forget your discovery that the CD4049 is a lousy linear amplifier and that a CD4069 would be better, would operate with less current  has fewer number of pins so is smaller. Good luck.
  19. audioguru2

    My Lab

    My cell phone has a cam. Maybe I could attach a pic of my lab to an e-mail from the phone. My daughter pays its bill so maybe she won't notice a charge for e-mailing one pic. If she notices then I'll buy a doughnut or coffee for her. 
  20. audioguru2

    My Lab

    My son moved out and took his digi-cam with him. I'm chatting with him on MSN right now. You guys have very neat looking labs. ;D
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