Grumpy_Mike:
Now what do you mean by "otherwise"? That covers an almost infinite number of things.
By "otherwise", I mean that when I connect negative to the place where I connected positive and positive to where I placed negative before but I understand that's just usual.
Grumpy_Mike:
That sound sample, is it the sound you are trying to generate or the sound you are getting on the call, the latter would be more useful.
The sound is what I am trying to get on the phone.
Grumpy_Mike:
I would get your teacher to approach the next level of educational establishment up, for a start. I am in the UK so for here it would be sixth form collages or collages of further / higher education.
I would be very happy if that happens here. By the way, the government is doing some effort in that and I wish that it goes successfully.
Grumpy_Mike:
And other good source of oscilloscopes is maker spaces, or Radio Hams most of these will be very friendly to your request. Of course you have to know how to use one once you get one, so see if its owner could come and help you.
Actually....., none of them I can get nearby. But I will try to find one.
I mean that when I connect negative to the place where I connected positive and positive to where I placed negative before but I understand that's just usual.
Yes swap the leads over and the result is the same only the inverse sign. A meter just measures the potential difference between two points.
So can you post a recording of what you get, maybe I could run it through my oscilloscope. That is nowhere like as good as making measurement on the real thing, but it might give me a clue.
Thanks for that, sadly it didn't give very much useful information, but at least it ruled out some things.
There is no evidence to suggest you have flattening on the tops of the wave, so that suggests you are not over driving the microphone. However it is hard to draw much from the audio waveform.
Have you tried a real microphone? That could show if the problem is somewhere else if it didn’t work. But really you have reached the end of the line without any test equipment.
Yes, I have tried a real microphone. It was working fine except slight zzz in the background but not as much as now. The voice was clear. I used this kind of microphone:
OK, lets try and bias the mic + input as well. I think 100nF is way too large for a restoration filter as it will act more like a low pass filter and cut off all the high frequencies in the sound, making it sound like it does.
Not sure what you mean. Capacitors come in all shapes and sizes. It is a capacitor, AC coupling is what it is doing in this circuit. It is not a special sort of capacitor.
Actually, I didn't use it last time.
We can only help you if to tell the truth. If you lie or mislead then we can not proceed to help you because we believe and formulate advice accordingly. There is a saying in computing GIGO, which means garbage in garbage out. It applies to fault finding as well.
Grumpy_Mike:
Not sure what you mean. Capacitors come in all shapes and sizes. It is a capacitor, AC coupling is what it is doing in this circuit. It is not a special sort of capacitor.
Ok
Grumpy_Mike:
We can only help you if to tell the truth. If you lie or mislead then we can not proceed to help you because we believe and formulate advice accordingly. There is a saying in computing GIGO, which means garbage in garbage out. It applies to fault finding as well.
I didn't lie. I just did not understood that there was a capacitor there as in the older schematic I read it as "0.1uf AC Coupling Attenuator" and you told that those resistors were working as attenuator so I completely misunderstood it. In the last schematic(which you sent yesterday) the words were written apart and then I knew that there was a capacitor. I too know about GIGO. Today I will add the capacitor and try with only one mid-rail bias and if that does not work then with two of them(one at + and other at - of the mic). It was just a misunderstanding.
I am facing a problem. If I disconnect the mic+ and leave it unplugged and just connect mic- to mid-rail bias or to GND. I get the same zzz sound then when I connect mic+ to the pin 9 directly(when the call is going on) there are some different tones of zzz (like za zo ze ) and then again that same zzz. (also when the call is going on)Same happens when I connect to pin 9 through filter and attenuator (those za zo ze tones and then same zzz). I get the no sound when I have unplugged both mic+ and mic- otherwise wherever I connect either of those wires I get zzz tones and then static zzz sound.
Don't think that the zzz are the siren or something else that I wanted. they are just some up down voltages.
