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Everything posted by sundar_milo

  1. A 4th order filter can do better in my project.First i shall design one and test it with different frequencies , plot the gain vs freq.
  2. Thanks for sharing those info.i am planning to use an algorithm for correlation between predefined recorded signal and the input voice signal and if it is closer to 1 then that instruction is executed whatever it has been programmed for. Just like the dot product of two vectors a.b=1 if they are parallel and a.b=0 if they are perpendicular, the correlation value is similar to that. Btw can u explain more on the attenuation part ? like the values that are needed to make a good filter .And im sure there is no way to filter all the signals other than the voice signals,but atleast it should contain only the voice band so that correlation is easier to perform and not tideous one.
  3. Hi MP. I want to design a voice recognition system using TMS 320 C54X DSP processor.To which im going to give the input voice signal through mic,amplifier and filter sections. First im concentrating in designing a good filter for this project.I dunno the attenuation and rejection values in dB for our voice signals .Even i came to know of the frequency range 300 Hz to 3 KHz from the above posts only.But i would like to know how to estimate these values for my project. Any help will be appreciated.Thank you very much.
  4. Thanks for those replies.Now im confused with these two circuits given in the links you have posted.But i would like to go with the one that has a single supply version.According to the circuit given in the link provided by Audioguru , it has to be fed with a dual supply(+15V and -15V).However a single supply can be converted to a dual supply , so there wont be much problem at all. The PDF file from yoyok has a half-supply generator that forms a virtual ground.So im planning now to use the ckt from Audioguru and feed it with power supply using the half-supply generator. :)
  5. Hi. I need a bandpass filter that should be able to allow only our voice frequencies and reject all other frequencies.I dont have any idea about the frequency range of voice but i think that is not a problem at all.I searched for BPF in google and found this : http://www.electronics-tutorials.com/filters/active-bandpass-filters.htm it will be easy for me to deal with Opamp based filters rather than others that use inductors. My input to the filter will be thru' a mic and an amplifier . Is this filter good for my project or is there any other filter that well suits my project? Also i doubt if the frequency range that i want to design is feasible. Any help would be much appreciated.Thanks. :)
  6. i also recommend you first create a pcb design using computer after making a scematic.and then u would have to print the board . for this design u need some pcb creator programs like express pcb,eagle layout editor. Eagle editor is the best one from user comments. but before everything we must contact experts for thier suggestion.dont even proceed to buy chips. just make a schematic first.
  7. i think u would need the following components common anode 7 segment display - 3 IC 74160 - 3 IC 7447 - 3 IC 7485 - 3 IC 7400 - 1 Resistors 330 ohm - 21. I doubt that some more resistors are needed for grounding and other purposes. i think we need some others' help to do the resistors job. If you are clear with my circuit diagram then make up a computer aided schematic. post it here and may be we can ask help from experts like "audioguru" , "ante" , etc., send them personal messages so that they could give some good idea about the circuit. i recommend www.maxim-ic.com www.ti.com ,etc., try googling . i always buy chips directly not by online.
  8. i dont know where you are from rybitski. but in dollars it would cost within 10 or 15 ithink(only the ic's).including others it might go upto $30 or so.
  9. hi im very sorry to post this late. :-[ just look at this pic and say what u think.
  10. Hey i have found a way to solve your problem of counting ,displaying in 3 digit display. It uses 3 IC 74160(counter), 3 IC 7485 (4-bit magnitude comparator ), 3 BCD to 7 segment display decoder(IC 7447) and an inverter (IC 7404). The circuit is somewhat complicated for me to draw but i will try to post the circuit diagram(schematic) within 2-3 days. But u have to provide the output of the IR to this circuit . i hope it is about +5v so that it could drive the counter circuit. Regards sundar :D
  11. i dont know about the schematic but i think u can find it in google.first tell us about the project you are upto.the ics i have mentioned are digital ICs .the link i have provided tells about the ics . http://www.kpsec.freeuk.com/components/74series.htm#7490
  12. yes i was thinking about that too. what im asking is that the theory is feasible or not in your first look . Also im a little confused with the keyboard thing.is there any specific IC for doing keyboard job ? i thought of designing the keyboard myself and finally came to demultiplexers(1 input , 2^n outputs,n selection lines).I also think that some ROM chip is available in market for this. consider an 8 bit number (00000000).as i said that i like designing my own keyboard rather than using EBCDIC and ASCII,i assume the first 2 bits from MSB as a dummy.i plan to use the other 6 bits since 2^6=64.this would be enough for alphabets,numbers,special characters and control strings . why im using 8bit is that the other 2 bits may be used for parity , etc. First designing a custom 6bit binary to 7x5 matrix converter would be the best idea.for that a 6 variable kmap could be used to get the simplified boolean expression .but this somewhat looks like a tiresome process.so i can choose a an IC to do this.i dont know which ic would do this wonder . help would be appreciated :)
  13. Thx for ur advice audioguru. can u say something about my idea in that above picture showing a block diagram of my thoughts. regards sundar
  14. here are the pin diagrams. have a nice look
  15. Hi rybitski. i think i may have answers for some of your questions. the IC 7490 is a ripple counter,which u could use it for counting.IC 7447 is a BCD to 7 segment decoder. search for its pin diagram in this site or in google. regards sundar.
  16. Hi again I've completed making the circuit as said by audioguru and it works PERFECTLY FINE .I also checked a NAND gate (7400) and it also works well.i used a 2 x 3v = 6v supply.i had some resistors with me,a 330 ohm and a 120,didnt use a 220 ohm but i will buy one and see the difference in light intensity. ive attached the picture of the circuit below.(batteries not included in pic
  17. Thx for ur replies audioguru. I was thinking to add a resistor between pin3 and the LED but i dont understand why u want me to add a 220 ohm between the pin2 and ground. I will test the circuit as u have said and i will tell the result tomorrow. Thank you very much. :)
  18. Hi everyone. Im a new member of this great site.I hope this is the best place for me to improve my knowledge. Im also a newbie to this electronic world.I have a thought in my mind to design a walkie talkie like circuit .But in my idea i want to design a circuit that can send and receive text messages wirelessly between 2 .im good in digital electrnics design n know about decoders,encoders,multiplexers ,demultiplexers,etc., and also how to design on my own.ive done
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