Hello, I want to make a simple microphone preamp from a schematic I found in the internets, but I am having some trouble with it.



What does tip/ring/body mean ?
And also I don't remember how to interpret transistor symbols, how do I find out which lead is the one represented in the symbol with an arrow?

http://en.wikipedia.org/wiki/TRS_connector#Tip.2Fring.2Fsleeve_terminology scroll down to Terminology, np man.

Also that's an NPN transistor.

Hmm I see.

Also, in the schematic and everywhere else it says the soundcard puts out 5v through the ring, but I tried measuring the voltage between the "body" and "ring" and there was none, only between the tip and body, what does that mean? Is my soundcard somehow inverted?

It would make sense for the +5v to be the TIP pin because if you look at the way the circuit is wired, when the transistor is saturated (i.e. completely ON) the node above the transistor is practically grounded and when the transistor is off the node should have +5v.

I know nothing about electronics except soldering and making PCBs, so does this mean it would or would not work?

Make sure you check that it is in fact compatible with your SB card and I think the pin config you have there is a pretty safe bet.

Btw I'm a 2nd year Electrical and Electronic Eng student ;)

The voltage on the tip is 2.78 V and it's not really a SB card, it's an onboard card, a realtek AC97.

Now I just cannot understand how PC microphones work on it

What's the purpose of the exercise, i.e. why are you making said Pre-amp?

It's because I have a dynamic microphone lying around and the circuit is so simple I felt like doing it

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I had an idea. What if instead of drawing power from that imaginary +5V my sound card was supposed to put out (I found out it just uses an alternative wiring) I used 2 AA batteries for 3V? Like this:



Do you think it work?

PS : ignore that thing that looks like a ground beneath the "line in body"

No.

You have to have an engineering of at least 250 to make that work.

No.

Ok then but why not?

--

I mean, what is wrong?

It might, but I'm not convinced. You should stick to the power supplied by the sound card and not use batteries because you'll find that in operation 2 AA batteries prolly give out about 2.4-2.6v, never actually 3v.

Tell me if it works.

I don't know much about electrical systems, but wouldn't it be more stable to just draw 3.3v from your PSU and reduce it to 3.0?

I don't know much about electrical systems, but wouldn't it be more stable to just draw 3.3v from your PSU and reduce it to 3.0?

This is potentially dangerous.

It might, but I'm not convinced. You should stick to the power supplied by the sound card and not use batteries because you'll find that in operation 2 AA batteries prolly give out about 2.4-2.6v, never actually 3v.

Tell me if it works.

But my soundcard puts out around 2.7 v anyway I don't think it would make a difference

Anyway thanks I'll post the results here after I build this thing (but it won't be so soon)