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  1. audioguru2

    Additional Information

    There are many single-supply, low-voltage-supply opamps. I don't know where you are or what you can get. What about an LM324? It is a popular quad opamp (4 opamps in one package) and is exactly the same as an LM358. Of course its package is bigger with more pins (14) and the pin numbers are...
  2. audioguru2

    60 Hz sine wave oscillator.

    Kevin, Aren't your "104" capacitors actually 0.1uF? At 60Hz, a 0.1uF cap has a capacitive reactance of 26.7K ohms. Therefore the 10M resistor across one doesn't change the phase, nor does the 500 ohm resistor across the other. Your circuit is nothing more than a single-stage integrator circuit...
  3. audioguru2

    60 Hz sine wave oscillator.

    Hi Kevin, Your circuit won't oscillate because it doesn't have any positive feedback. It also doesn't have a bandpass filter. If you changed parts around and made it into a similar Wien Bridge oscillator, then it won't produce a sine-wave because its uncontrolled output level will clip...
  4. audioguru2

    L200 Reg plus LM741 Op Amp PSU

    Hi Woody, The spec sheet for the premium LM741 lists a max supply of plus and minus 22V which equals a total supply of 44V. The lower quality "C" version is listed at a total of 36V. It should be fine in your 30V circuit. All of its spec's are listed with it operating with 30V. The opamp's...
  5. audioguru2

    sphygmomanomater.

    Hi Xoy, For measuring blood pressure? Then it's a meter, not a mater. A mater raises purebreds. He, he. ;D
  6. audioguru2

    Additional Information

    Sure you can, then its negative output voltage or the entire positive and negative supplies across the 4017 IC will blow up the poor 4017! ;D ;D
  7. audioguru2

    MOSFET for high voltage and high power

    Hi Alun, I was going to say, "PERFECT!", but realised that its 320V rating is awfully close to the peak voltage of 220VAC (I have 120VAC over here). I wonder what the LDR does during over-voltage breakdown. When your 'fridge turns off and makes a voltage spike does it get destroyed or does it...
  8. audioguru2

    MOSFET for high voltage and high power

    Hi Plouf, 1) Good, you understand about DC pulses. 2) Mosfets are not made with a gate that can withstand 309V. Also a Mosfet will get too hot if you use it like a linear amplifier. 3) I have never seen a high-voltage photodiode, phototransistor or LDR. Pulse-Width-Modulation does not make a...
  9. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Tedy, Of course it doesn't work, you didn't use the transformer that it specifies and you didn't read this topic about how to fix it. Sure, those tiny rectifier diodes and R7 are going to smoke! If you use a transformer with a higher voltage to allow it to work better, its tiny 2N2219 will...
  10. audioguru2

    Additional Information

    Hi Naveed, The Dancing Lights project is here (copy-shortcut on its link): http://www.electronics-lab.com/projects/motor_light/021/index.html 1) IC1A and IC1B are both inside the LM358 dual opamp so they are both powered by its pins 8 and 4. 2) The LM358 is a single-supply opamp that doesn't...
  11. audioguru2

    Datasheet

    Hi Chauhan, Welcome to our forum. Google is full of projects using a PN3906 transistor but don't say which company makes it. I think that it is some company's house-numbered 2N3906 transistor. The datasheet for the 2N3906 is available with a Google search, go to www.google.com or click on the...
  12. audioguru2

    MOSFET for high voltage and high power

    Hi Plouf, Thanks for posting your circuit. 1) Of course it has pulses. The output of the rectifier bridge has half-wave pulses of 309VDC peak at 100Hz. Since the pulses aren't filtered, the average voltage at full brightness will be 218V. 2) The transistor in the optocoupler and the gate of the...
  13. audioguru2

    If you are looking for good PLL FM Tx, Look at this Link

    Thanks, Shahriar, Those are nice transmitters. They have enough output power to jail people in my country who use them, because our FM dial is full and the transmitters will cause interference to existing stations. I don't like the simple audio limiters. They will cause very bad distortion.
  14. audioguru2

    Have anybody Build that "4 Watt FM Transmitter " In projects section

    Hi Shahriar, It ain't easy to transmit with a simple transmitter. 1) Pre-emphasis is the treble boost that all radio and TV stations use. De-emphasis is the corresponding treble cut that radios and TVs use to reduce hiss and return the audio to normal sound. The audio corner frequency depends on...
  15. audioguru2

    Electronic Stethoscope 2

    Hi May, Welcome to our forum. The project's Circuit Description clearly describes the functions of its 4 parts: Microphone Preamplifier, Low Pass Filter, LED Driver and Audio Power Amplifier. Can't you make your own block diagram with these boxes on it? You could also add 2 more boxes: a...
  16. audioguru2

    DC/DC Converter

    Hi Twiddle, Welcome to our forum. Perhaps your post isn't long enough. It is easy to make a voltage-reducer that doesn't have any load current.
  17. audioguru2

    Have anybody Build that "4 Watt FM Transmitter " In projects section

    Hi Shahriar, A 4W FM band transmitter is very illegal in my country and might be even more illegal in yours. That transmitter doesn't have pre-emphasis. Are you using an ordinary radio to receive it? An ordinary radio has de-emphasis that might corrupt your data. What frequency is your data...
  18. audioguru2

    MOSFET for high voltage and high power

    Hi Plouf, Please post your dimming circuit for us to see if it has pulse-width-modulation that is sync'd to the DC pulses of the diode bridge. Without syncronization, the light will flicker. You can avoid flickering if you filter the DC pulses with a huge capacitor, but then the DC voltage will...
  19. audioguru2

    Additional Information

    Hi Naveed, Welcome to our forum. We'll be glad to help you!
  20. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Thomas, This is an international forum. I'm in Canada, eh, with Niagra Falls' generators (alternators?) producing umpteen gigawatts of power nearby. When I first measured my mains, I was surprised how much its voltage changes. Sometimes the utility reduces the voltage on purpose making a...
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