TriGeminal

Sorry, belated :) I measured the batteries .. one was 8.4v and the other was 7.2v! I think that difference might be counted :)

It's doesn't give any light (maybe hardly I can see it!) yes, R12 instead of 330k I put 270k because I lost my 330k .. also I connect solid single wires with standard several fine wires ones :) They're the same I used the first time, but I didn't measure the voltage :)

After a while I decided reloaded the project again, I still use the breadboard but just re-connected the wires and get longer wires with clips for the batteries and speakers .. I connect it to the audio card in my computer and I get this noise all the time (even if I removed the entire mic!) Is it receiving signals from air or something? :) Thank you problem.zip

Thank you steven :)

Thank you SM2GXN :) It seems cool 8)

what is the simplest circuit attached to a MIC? Cause I'd like to attache the circuit to my sound card an make amplifications with the computer ;D Thank you :)

Thank you MP, much appreciated :)

I just bought a solder, which I guess had a large percent of lead .. even lead free solders can be more dangerous than solders that have lead! I used another type, which had low amount of lead .. it was better, but same case, I had a weak respiratory system for days .. When I was 6 years old I was used to use that type of solders and never had a problem, so I guess it's the place I solder .. it's not highly ventilated :) Anyway, I'll be making a subdomain for that stethoscope, with shots and videos of every step in addition of medical hazards (cause we are medical students :D) ..

I soldered the circuit on a veroboard .. it didn't work (cause bad joints mainly) .. anyway I'm not going to solder anything again after I was ill for 2 weeks cause of the toxic fumes :( I'll try again with the breadboard circuit ... but I'm thinking to simplify the circuit .. I mean I'd like to give my computer a chance in amplification, so I'd like to know what is the simplest circuit attached to the MIC that makes sounds reach my computer? I can use many programs to amplify the sound, just a matter of time :)

My clear Heart sound ;D I got a semi-shielded mic + pluged the audio jack into my computer .. then recored by jetaudio program .. The air noise (some bad noise like air noise) are still mysterious!! I think I've a problem in something at the breadboard, that's why I'm soldering another one :) Those noise can be heard even without connecting a mic!

yes, that's exactly the circuit :)

Thank you Audioguru, Here's a link for Quicktime alternative to play video files (.3pg) I'll solder the parts and apply a shield, I think it might bring better results :)

My friend could assemble the exact circuit at this link: http://www.electronics-lab.com/projects/science/019/index.html Here's it on the breadboard: Here's the sound "Puffing": See the Video The heart sound was very strange: Here's an mp3 amplified file Changes in that circuit, I didn't find 3.9 Ohm, so I replaced it with 4.7 and I've not applied a shielded cable yet :) Was the 1st link about the circuit in this site working, or there was another one? ;D Thanks everyone, specially Audioguru 8)