Let's Make Robots!

How to get a precise amount of voltage

Hi guys.

I am working on my ISD4002 chip and i am now going through the recording part. This is what the manual says:

"[...] a 32 mVp-p (peak-to-peak) maximum signal should be capacitatively connected to this pin for optimal sound quality"

anainput.jpg 

My question is: how can i be sure the right amount of voltage is gonna enter that ANA IN+ pin? I am also not sure how to measure the source voltage (coming from the "line out" hole from my computer).

 

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

BTW, what's that symbol in the second schematic (the second one in the hardware section) that shows the 4.7K resistor with an arrow pointed to it?

 EDIT: sorry, i got it. It was one of my dumb moments 

thanks mate, but i also had found that site before :) 

But how can he know that with a 4.7K resistor he will limit without knowing the aumount of current he wants to flow in? What i mean is.... i could find out the correct resistor if i also knew the current needed, but without that i don't know how to get to it.

I am gonna use the 4.7K resistor, but if i don't find out why i won't sleep peacefully tonight :D....this happens with every project of mine actually :) 

Hi,

I have found a swedish website. In the schematic a simple potentiometer have been used on ANA IN+. A higher voltage will only result in a distortion of the output signal, it will not kill the chip. I am not shure about the lineout voltage from a soundcard, but I think it can reach 2Vpp.

Hope this will help you.