Author Topic: Peak to peak voltage from an audio jack  (Read 11007 times)

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Offline mathk

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Peak to peak voltage from an audio jack
« on: May 09, 2012, 06:05:47 pm »
All is in the subject. I have done some search on google here and there but did not found any answer. So what is the typical peak to peak voltage of an audio jack?

I have the idea to do a project that would take the audio sound out from my laptop sample it and transmit it wirelessly to my home cinema.
Any advice are welcome.

i just want to do it for fun and practice so it might sound pointless for you.
 

Offline SeanB

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Re: Peak to peak voltage from an audio jack
« Reply #1 on: May 09, 2012, 06:18:02 pm »
Nominally it should be 700mV RMS ( 2V peak to peak) into 600R but often it varies from manufacturer to manufacturer, it can be 150mV into 1k to 5V ( BMW head ends).

Laptop audio out is normally meant to drive 32R headphones, so at max it will be around 4V P-P, with some pretty bad distortion. At a more sane level it will be 0.7V RMS, and use a load resistance of around 1k, so it will pretty much work direct into the audio side of the transmitter. Quality will not be the best, is it not possible to use an USB cable and an USB audio device instead?
 

Offline mathk

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Re: Peak to peak voltage from an audio jack
« Reply #2 on: May 09, 2012, 06:23:36 pm »
It is a macbookpro.
Spec says: Audio line out/headphone minijack (digital/analog)

What would digital means?
 

Offline saturation

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Re: Peak to peak voltage from an audio jack
« Reply #3 on: May 09, 2012, 08:01:55 pm »
Mostly probably dual analog and S/PDIF optical.  Most all PCs with analog earphone jacks are mostly TOSLINK optical capable using S/PDIF cables.  Its the consumer version for optical quality audio output.


It is a macbookpro.
Spec says: Audio line out/headphone minijack (digital/analog)

What would digital means?
Best Wishes,

 Saturation
 

Offline T4P

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Re: Peak to peak voltage from an audio jack
« Reply #4 on: May 10, 2012, 03:32:11 pm »
It is a macbookpro.
Spec says: Audio line out/headphone minijack (digital/analog)

What would digital means?

SPDIF i had that on a HP laptop before , you could see the laser if you inserted the jack slowly
 

Offline mathk

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Re: Peak to peak voltage from an audio jack
« Reply #5 on: May 13, 2012, 09:13:34 pm »
Nominally it should be 700mV RMS ( 2V peak to peak) into 600R but often it varies from manufacturer to manufacturer, it can be 150mV into 1k to 5V ( BMW head ends).

Laptop audio out is normally meant to drive 32R headphones, so at max it will be around 4V P-P, with some pretty bad distortion. At a more sane level it will be 0.7V RMS, and use a load resistance of around 1k, so it will pretty much work direct into the audio side of the transmitter. Quality will not be the best, is it not possible to use an USB cable and an USB audio device instead?

Thanks SeanB. Would it be difficult to build my own USB Audio device? And if yes what do you recommend for my project?
 

Offline Psi

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Re: Peak to peak voltage from an audio jack
« Reply #6 on: May 14, 2012, 01:08:52 am »
If you plan to sample it why not just use the digital out, then the sampling part is already done.
Greek letter 'Psi' (not Pounds per Square Inch)
 

Offline electroguy

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Re: Peak to peak voltage from an audio jack
« Reply #7 on: May 14, 2012, 11:36:01 pm »
I also agree using digital output, saves you the trouble of sampling.
Good luck. If you don't get your project working, buy a ready made audio transmitter for $5 to $8. Plenty for sale on ebay.
You can even get USB to FM. Or audio to blue tooth and then convert blue tooth back to audio.
There are 10 types of people that understand binary, those that do and those that don't!
 


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