Foo - How much voltage into Line in?

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View Full Version : How much voltage into Line in?

phantomcow2
02-19-07, 07:49 PM
When you have a microphone or whatever else you might plug into the "Line in" jack on your PC's sound card, how much voltage is actually going in? Or, how much voltage is permissible to enter in here?

RedHairedScot
02-19-07, 07:56 PM
When you have a microphone or whatever else you might plug into the "Line in" jack on your PC's sound card, how much voltage is actually going in? Or, how much voltage is permissible to enter in here?
Now that's a coincidence. I'm just now about to try to run from my pedal's output jack into my compy's line-in. Hope that works...

phantomcow2
02-19-07, 08:12 PM
Well my plan is to make my souncard into a digital oscilloscope. Might as well get some use from it

jsharr
02-19-07, 08:13 PM
1.21 gigawatts

VegaVixen
02-19-07, 08:26 PM
Voltage doesn't move. It's a potential across two different points in a circuit. Jes' saying, since that's gonna be on your next test. :p

My Ratshack microphone uses two AAA 1.5V batteries, though I can't tell without taking it apart if they are in series or parallel.

Perhaps Catatonic has a better answer for you.

Minesbroken
02-19-07, 08:28 PM
When you have a microphone or whatever else you might plug into the "Line in" jack on your PC's sound card, how much voltage is actually going in? Or, how much voltage is permissible to enter in here?
I would say between 2 and 8 probably like any other preamp.

Minesbroken
02-19-07, 08:40 PM
its quite possible that its even less depending on the size of your microphone and its intended purpose.

phantomcow2
02-19-07, 08:40 PM
Voltage doesn't move. It's a potential across two different points in a circuit. Jes' saying, since that's gonna be on your next test. :p

My Ratshack microphone uses two AAA 1.5V batteries, though I can't tell without taking it apart if they are in series or parallel.

Perhaps Catatonic has a better answer for you.
Fine:p
How much potential difference between charges can exist, allowing for movement of electrons to and from my soundcard?

VegaVixen
02-19-07, 09:04 PM
Perhaps a better way to ask is: what's the max rated voltage allowed at the input of my soundcard? With the implication that the second point is at the output of whatever device you're pluggin' in.

Does your o-scope have a rated electrical output?

02-19-07, 09:06 PM
Voltage doesn't move. It's a potential across two different points in a circuit. Jes' saying, since that's gonna be on your next test. :p

My Ratshack microphone uses two AAA 1.5V batteries, though I can't tell without taking it apart if they are in series or parallel.

Perhaps Catatonic has a better answer for you.

Probably in series.

iamlucky13
02-19-07, 09:30 PM
I think only a couple of volts.

This site (http://www.zelscope.com/faq.html), which also has some O-scope software, mentions using a buffering circuit. He also has a schematic for said circuit linked to in the FAQ.

RedHairedScot
02-19-07, 09:31 PM
Now that's a coincidence. I'm just now about to try to run from my pedal's output jack into my compy's line-in. Hope that works...
It works...well.

pc: check out zelscope and xoscope for good soundcard-as-scope stuff. The schematic indicates that the max voltage it'll put out is 12V (or, +-6V). A footnote says that it's adapted from a circuit in Art of Electronics by Horowitz and Hill -- if you don't have that book, starve until you get it. It's bit and gray and awesome!

ax0n
02-19-07, 09:32 PM
I've found line level is usually around 5v or so. Much more than that, you start to run out of headroom.

redfooj
02-19-07, 10:25 PM
line level output for car cd players range from 1.5 to 8v , typically 2 or 4
i think computer sound cards are in hundreds of millivolts (sub 1v)

grapetonix
02-21-07, 09:56 AM
I was going to say about 1 volt peak to peak and i nearly remembered right. (0.32Vrms = 900mV p-p)

http://en.wikipedia.org/wiki/Line_level

cpb406
02-21-07, 10:04 AM
The audio inputs are designed to accept high-level audio signals: 2 Vrms or +8 .2 dbu, which is the standard output level from CD and DVD players.