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hakyman

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Everything posted by hakyman

  1. hi everybody , me and my friend have designed( actually changed smth on a schematic:) a reg for non simetric transformer the point is the transformer connections. its workin ok now, but i dont have a chance to measure or see all effects on output, is that kind of connections has a disadvantage , we dont have a simetric output transformer right now so we have done that, pls help us for a further and better reg with output of + and - voltage. and if u got any other opionions pls let us now, for eg. current amplificaiton . we thinkin about add some outputs for stabile +5v +9 +12 and we have to take theese outputs from the connection point of c3 and c5 too, unfortunately this transformer is the only big power transformer we have got, it has 0 24 48 volt ac outputs, i can find a lineer one like 48 0 48 around also they are a little expensve for us so we use it like this is that effect bad?or what could happen? any modification idea or needage for better reg? thnx for help sorry for bad english :)
  2. Hi Hotwaterwizard thanks for the reply i have the datasheet but i'm searching for a replacement cause it cant be found at electronics shops at around. thanks best regards
  3. Hi i need to learn if there is a replacement or similar part to CA3237(IR preamp). cause i cant find it around thanx best regards
  4. hi Audioguru i did not do special cahnges on filter block still sallen n key type but i just set the cut-of to 1500Hz coz i said before i work on both heart and respitory sounds and respitory sounds range is 70-1200 hz. i added a digital filter at 8th degree to choose the heart sounds. i know the analog filter seems useles but teachers said there should be an analog type filter so i added:) very very best regards
  5. hi Audioguru Here is my measurements(all values r max, means i hit the stethoscope head as strong as i could do ;D ) output of steth. circuit; ACV =1.5V (with no load) DCV =+/-1.5V(with no load) ACA =12mA (with no load) resistance in ohm of PC sound car dmic input=unreadble(over 20Mohm) when the circuit connected to PC sound card mic input ,current flows to PC; ACA=0,950 mA additional info = sound card adds a 0.02mv Ac componenet onto real signal i use 9V alkaline batteries and i limt the circuit output voltage with limiter dioades and i set the volume as low as possible cause my main purpose is monitoring the heart and respitory sounds so i did some differences on filter block. i dont fright from the output voltage but i'm not sure about the current but 0.950mA cant damage any kind of sound card i guess :) but i want to be sure and what do u think. is there any value have no-sense or unexpected??? specially is 0.950mA too low for 1.5V in AC ? thanxxxxxx
  6. hi Audioguru i'm not powering the mic from sound card. i use the sound card as a receiver for PC like the Rf TX circuits connected to the PC. actually its again about the ur electronic stethescope project. i wrote a parallel port and sound card program to monitorising the sound and added a digital filter for better responce but i got some problems with par.port while real time monitrizsing and matlab have so much advantages with sound card mic input. generally sound cards powering voltage is 5 Volt (for stereo)so i think it will accept the 5V but i'm not sure about the current. i tryied the circuit at different 5 PC and had no problem it acts well but i would like to learn standart if it exist :) i dont think the output of sstethescope project damage any sound card but i'm not sure again .. thanxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx(and i will add ur name to my thesis "thanks to" part:)
  7. hi everybody i'am searching for a standart for sound cards but i cant find smth about it. i read much tittles about it but there is no standart i could find. is there a standart for sound cards for Acceptable voltage to mic input?????? or what is the worst sound cards max aceepptable voltage for mic input. i working on it and i have no problem with my sound card(ac97 cmedia) with max +/-1.5 V DC but what about other sound cards ?????? thanx
  8. hi guys thanx for the replies audioguru could pls make it some clear cause i dont see ever a mouse kit with rf i only use IR kits. and do u know a link have some schematics without a needage of antenna of transmitter. u can write to the link to alun gave at above where u discuss about transmitters . thanx very much very very best regards
  9. hi Audioguru !!!!! how r u ?for a long time later i come back :) i finished the circuit and the matlab program to analyse the heart and respitory sounds.thank god :) anyway now i want to add a trnasmitter and receiver circuit because the cables really annoying hehe anyway what u suggest? i am searching for a simple, stable, and if possible without a needage of antenna hehe do i want so much things . i know i should write theese in another topic.but i want to get ur opinion . thanx very very speciaal regards ciaooooooooo
  10. hey guys ; i have got a little problem here , i bought a phototransistor but i cant find the datasheet . the only thing writed on the device is ; 3E 1001 D , i ahve searched in net and datasheets but i cant find something. i think the numbers are explanation numbers its a 3 pin phototransistor. pls helps thanx already....
  11. hey what is it i dont know what is afun card ? could anyone explain that what is used for ? thanx and sorry for ignorance:)
  12. hi audioguru. how r u do you remember u recommended using a peak detector and a rectifer circuit to me to fix the output for an ADC. i tried so many times the peak detector circuits and i cant get the reason for using it. i use a adc0804. and the peak circuit just do the sampling duty like the ADC circuit can make it own. if i change the capacitor values of peak detector(change time duration) the circuit only help to find the max. peak of a cycle. and may i ask which point is the best for taking output to ADC.is the output point of amplifier(LM386) or output of the filter part. which one should i use. my amplifier(lm386) output is about 4.2V without a sound in the mic(change with the volume control pot.changes and it can up to 4.5V). and it swings with a heart sound around 4.2V(about 3.7-4.8) could i use the ADC directly and last one thing i use the 5.th pin of LM386 for output taking before 1000uF which its anot goes to headphones jack. this is all :) i am very dogged to get the knowledge. if u can send me a circuit or just a block diagram i'll be so much happy and thanksfull. i search so much but i cant understand the death points of the circuits that help me find the circuits how to work. may be my english is not sufficient or may be their english is worse than me :) whatever thanks already.
  13. hi all what about low frequencies is there any solution without taking the antennas lenght bigger?or is there any type antennas has small dimensions?
  14. Hey Audioguru You did again thank you so much for your kind and quick reply again i dont really know how can i thank to you thank you so much i'am gonna out of city for a week time. so i ll send the LF353(jfet) setehescope with a LM386 amplifier after i came back. see you thanks for all
  15. Hi Again. I've got some questions about audio application and the electronic stethescope-2 project components. i need the reasons of selection of the components. 1)why u choose theC7=1000uF and C8=470uF and what is the purpose of these components? 2)there are so many electret mic powering circuits in different values of components why you choose C1=470uF R1=10K and R16=1K what is the purpose? 3)U1a is a buffer and why we choose the gain about Kv=22 what if when we adjust the gain in lower or higher value?and why all buffer and booster circuits have negative feedback? why non-inversing input not select?To avoid the offset or the noise? 4)U1b is a low pass filter with the cutoff frequency 103Hz but why you choose this frequency why not 200Hz -- the max frequency of heart sounds?and if we choose the values like; C3=C4=100nF and R5=R6=1.5K(it gives the nearest cutoff value about 106Hz)i mean why you choose these values any reason for that?if i change them with the values i gave above, will be any differences? 5)what is the purpose of R7 and R8 why you need the feedback and how you define the values of R7 and R8? 6)why you dont use the bypass pin of lm386(pin 7)? what means bypass? 7)what is the reason to choose the rectifier circuit(C6 and R15) values why 1000uF why not another value why 15K. what is the purpose of using C5=0.1uF and R14=3.9 as little value as this?what if we remove it or change? 9)has the filter part any effects on gain? 10)anybody calculate the matematical models of the circuit? 11)don't we need a High-Pass Filter.isn't be better with this ? 12)what if we change the LM386 with a different amplifier as 20W or 30W ?is the pre-amp part o/p can drive the power amplifier has a power of 20w or more ? Additional Basic Questions; 1) what is a pre-amp and what is main reasons for using. which part it has got to have? buffer,filter,booster,...? 2)what is a booster what is its purpose? 3)what is buffer what its purpose ? ... it goes like this i want to know them totally i know some but i havent got a real background on audio electronics so i cant set up the relations efecting each other. Thanks to all who try to help me and answer my Questions thanks.... here is the schematic again if there is anyone not see before still
  16. Hi Again. I've got some questions about audio application and the electronic stethescope-2 project components. i need the reasons of selection of the components. 1)why u choose theC7=1000uF and C8=470uF and what is the purpose of these components? 2)there are so many electret mic powering circuits in different values of components why you choose C1=470uF R1=10K and R16=1K what is the purpose? 3)U1a is a buffer and why we choose the gain about Kv=22 what if when we adjust the gain in lower or higher value?and why all buffer and booster circuits have negative feedback? why non-inversing input not select?To avoid the offset or the noise? 4)U1b is a low pass filter with the cutoff frequency 103Hz but why you choose this frequency why not 200Hz -- the max frequency of heart sounds?and if we choose the values like; C3=C4=100nF and R5=R6=1.5K(it gives the nearest cutoff value about 106Hz)i mean why you choose these values any reason for that?if i change them with the values i gave above, will be any differences? 5)what is the purpose of R7 and R8 why you need the feedback and how you define the values of R7 and R8? 6)why you dont use the bypass pin of lm386(pin 7)? what means bypass? 7)what is the reason to choose the rectifier circuit(C6 and R15) values why 1000uF why not another value why 15K. 8)what is the purpose of using C5=0.1uF and R14=3.9 as little value as this?what if we remove it or change? 9)has the filter part any effects on gain? 10)anybody calculate the matematical models of the circuit? 11)don't we need a High-Pass Filter.isn't be better with this ? 12)what if we change the LM386 with a different amplifier as 20W or 30W ?is the pre-amp part o/p can drive the power amplifier has a power of 20w or more ? Additional Basic Questions; 1) what is a pre-amp and what is main reasons for using. which part it has got to have? buffer,filter,booster,...? 2)what is a booster what is its purpose? 3)what is buffer what its purpose ? ... it goes like this ;D i want to know them totally i know some but i havent got a real background on audio electronics so i cant set up the relations efecting each other. Thanks to all who try to help me and answer my Questions thanks.... here is the schematic again if there is anyone not see before still
  17. hi Audioguru i see u r online and i'd like to ask that what kind of earphone u recommend? thank for helps i dont know how thanks to you i'm trying a new stethescope project with lf353 i ll send the circuit when i finished modyfying thank again ...
  18. Hi Audioguru Happy new year too. i also checked the circuit(elec. steth.-2 project) and it really works good but i have problems with earphone i use a sony ear-in headphone and one of its ear burst. i still got some pit pats(pıt:)(seemed like this because my alphabet is not suit:) i checked the datasheet of TL072 and they named the o/p of first opamp in TL072(pin 1) as offset-null pin. i cant understand what it is(datasheet from ST microelectronics the producer site)i send the pin connection jpg. and i'd like to ask what is the purpose of peak detector using on converting the o/p of electronic stethescope to digital? Thank You so muuuuuuuuuuuuuuuuuuch audioguru u helped me to get over this if you send me a good earphone it ll be perfect ;D thank u so much again ...
  19. i' really sorry i forgot smth. i connect the mic to the stethescope's one ear. i couldnt cut the tube cause it is littmann and so expensive ;D whatever i got the heart sounds so clear but it has pıt pıt in the heart sounds i dont know how can i explain. it sounds like more sharp. i wish you get me audioguru what i mean. and its harmfull to my ears when i touch wrong place of steth. i get all the diaphram sounds and its really annoying, my ears ache cause of that. and last thing ;do i need offset the TL072 it has a null pin but some differences with 741 and i dont know sould i or how i do. thats all i know i ask so many questions but this is important for me i struggle to do the best. im sorry so many many thanks again wait for answers...
  20. hi again i built the circuit but it seemed not so good. the filter part seems ok when i give a sound like sssssss it not sense to this but i gave a bass sound like boooo yeah it give an o/p. but when i heard a sound its have pıt pıt pııttpı i cant understand what it is and it get louder when i gave a louder sound(give my breath it has no sense to all standart voices in speaking). this result same in both a 4ohm 5W hop. and with a sony headphone(ear-in i havent get a earcover one yet). the reason is the load(hop or headphone)? and i only had a o/p stage as -/+ 1.5 V max. when no input(no sound) the o/p swings between +/- 20mV at this time my pot adjusted to 1.9K. i used a 5K pot no form as 2,5K pot in my land and i dont think it'll effect but if yes i can change it with a 2K pot . i took all leads as short as possible(the mic lead is about to 10 cm). any change or correction on circuit? pls help me who work it with no problem . i remember doctor emad and audioguru succesed.thanks for your helps again ...
  21. Thank you so much audioguru for your kind and quick reply. i get the components. i'll share my experiments with you when finished and then ill add the circuits to apply an ADC circuit and try the output convert in digital. Thank You so much again...
  22. hi again. audioguru u wrote the cutoff frequency of LPF is 103hz but i read that the heartsound frequency range is 20 to 200 hz. and for medical care the cutoff should be 600hz(for listening lung etc.) what do u think? i'd like to say smth about the lm358 circuit i built it up and i get a weak sound (from a 4ohm hop.)but no noise then i connected its output to a amplifier lm1875 but i couldnt get an output what could the reason is? could anyone send a amplifier circuit for lm358 pre amp circuit? and last one thing what kind of ecm is used i use a electret mic has very low value. thanks much
  23. hi audioguru. i need to ask that the output of the circuit is sufficient to apply to a adc circuit. could i transfer the output to a pc in digital format. i mean i want to monitor the output signal of this circuit on pc. and second question; can i add a power amp circuit to output of this circuit to amplify better (like lm1875). is it possible? thanks alot already. ihope i can explain my questions well sorry for the bad english ;)
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