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Everything posted by Emad

  1. Hi all Ihave made the original ,the corrected and the elect. steth. 2 about one year ago The original didn t work and the other two worked. The best one was the corrected circuit. The stethoscope should hear the sounds between the 1st and 2nd , and the 2nd and 1st heart sonds , like murmours as systolic and diastolic , also clicks and so on. So there shoud be no noise . I hope to find a new project using 3v supply and a small head phone like that used with mobile . This will be more practical and I can use it in my clinic. Thanks to all especially audioguru.
  2. Hi all I made these circuits many times without the part involving the bipolar diod and they were operating. About three times they suddenly become badly operating.they respond to knocking on the diaphragm of the stethoscope but not to the heart sound.I dont knoww the cause. I hope you give me advice. Thank you.
  3. Hi audioguru many thaaaaanx Realy I dont know how to thank u. Forgive me my english is so bad to do that
  4. Hi Audioguru sorry for being back so late I want to ask about modifing a circut working on 3 volt and used as an hearing aid as a stethoscope?? this circuit is present in this site http://www.electronicsforu.com/EFYLinux/circuit/aug2003/CI-2-hearing-aid.pdf Shoud it do well if a filter circuit is added between transistor 1 and 2 ????? Many thanx
  5. Hi Audioguru If I want to use the 220 volt supply for the stethoscope,what rectifier circuit could be used . I hpe you post it. Is there any modification in C7 and C8?????
  6. Hi Audioguru Ihad reversed the variable R and had controle on volume . The sound is good in about 1/4 the range of the volume controle or less ,then there is mutch distortion. By putting 1k risistor paralell to R4 the noise disappear but heart sound become weak and respiratory sounds are not percepted. I think this circuit needs some slight modifications that I dont know. thanks for help.
  7. Hi Audioguru. I built this circuit with the TLO72. There is mutch noise. When lowering the volume there is a sound like hissssssss ,then after slight raising of volume heart sound is very laod and there is nearly no effect of increasing the volume . My mic cable is about 2 meter long but it is well sheilded. I use a real stethoscope head that already amplifies the sound before coming to the mic. What about putting R3 again in the circuit???? and what is your advice???
  8. Hi Steven These circuits use propes that shold be connected to the body. Is there acircuit producing pain relief without contact to the body??? Many thanx
  9. Have anyone heared about a circuit that relieves pain ??? If there is a circuit like this pls tell me . THANX ALOT.
  10. Thank you Audioguru. I ll try 4.7nf tomorrow
  11. I tried 20 nf for the two and then100 but the heart sound became very fiant in the both attempts. The circuit is good with its original capacitors. I had put a link to your project in an arabic electronic forum. I dont know shold I have been first taken a permission from you or not ???/ If so I can delete it . her is the site: http://www.arabteam2000-forum.com/index.php?showtopic=49466
  12. Hi Audioguru You knoe I built what is called the corrected circuit using 2 TLO71 and LM386. It works well. Is the E.Stethoscope 2 the same. ?? Have you built it?? Which battery is connected directly to the LM386??That one connected to 470 uf or that connected to 1000uf. I wonna tell u that the circuit named E.auto stethoscope is bad,I asked u about it before.
  13. Hi Audioguru I built the circuit named auto stethoscope. It works but your circuit is mutch better . I want to ask about C7 and C8. You said 1000uf for C7 and 100uf f or C8 I noticed that one battery became very week. What is the cuase??? Also could some components be changed to make the tone of the sound less huge?? Many Thanks.
  14. Audioguru. Thank u again . I wonna tell u that I built the circuit without the IC which is connected to the bipolar diode.I wanted to decrease the size of the board and also the mistakes.
  15. Hi Adioguru. I constructed your corrected circuit. It is more than excellant .No distortion , minimal noise and the sound is the same like a real stethoscpe. I can hear my heart beats and respiratory sounds laod and clear from above clothes . I dont know how can I thank you fore helping me . thaaaaaaaaaaaaaaaaaaaaank youuuuuuuuuuuuuuuuuuuuuuuuuuu
  16. hi Audioguru. I consrtucted the circuit with the TLO72 on a test board but there is just noise and nothing from the mic goes to the earphones. What is your opanion about this circuit in the site I put here , and can I use TLO72 insteed of NE5532 ?????
  17. Audaguru. I wonna ask about the function of U4 which is connected to the bipolar diod in this circuit . Can I make the circuit without it???????I think it produces flickering sound as light???
  18. Hi Audaguru. I sent for the TL072 but I dont know it will be present or not. I told u before that I connected the output of the LM358 to the input of the LM386 using just two ICs and I have a satesfactory result. I removed some noise by adding 0.1uf between the variable R of U2 and the negative volt. I ask if I can put anoise removing circuit between the two ICS????? If I can, what is the suggested circuit????? THANX
  19. this is the preamplifier I used-----R1 R3 R4=10K----R2+1K--R5=100K to 1M-----C1=0.1uf ---C24.7uf
  20. There is no distortion but just a sound like air or shshshshshshsh. the components around U1 are not the same like the original nor the corrected circuit . I had a diffirent circuit for U1 that Ill post it after I drow it . many many thanx .
  21. Audiguru. Iforgot to tell you that I took the LM358 from the shop and when Iwent home I found it KIA358 and I used it. This IC doesnt need a ground and so I used a single battery, just positive and negative
  22. hi Audiguru. I had no TLO71 in my area so I tried to use to use just one IC as apreamplifier and another one as an amplifier------- Just two . the preamplifier is LM358 and then the amplifier is the LM386 as that in your corrected circuit-------I hear my heart beats very well------- Ijust need trying another headphone as I expect sound to be better if I use an earphonr other than my mobile headphone. THats what I did . Thank you audaguru
  23. Hi audaguru. LM386 is the U1 or U4. Are C3 andR7 connected to pin6 ofU2 or just connected to each other . Many many thanx for your help and your being patient with me .
  24. Hi Audaguru . What is the value of R16 in the corrected circuit. How many ohms or kiloes?-------
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