AUX to Optical Konverter (Schematic)

[oliver1]

Hello – I found an old Sonos soundbar at home a long time ago that’s still working and sounds great, but unfortunately it only has an optical input and my PC (which I want to connect to it) only has an AUX output. Since I have to do a school project for which we have one month, I decided to build an AUX‑to‑optical converter. Unfortunately, I couldn’t find any schematic for an AUX‑to‑optical converter online, and ChatGPT wasn’t able to help me either. Now I’d like to ask the DIY Audio community if someone could create such a schematic. You don’t need to do the PCB layout—that I can handle myself. The converter should also be stereo, since the soundbar supports that. Our only rule was that we weren’t allowed to program anything. And if possible, it should cost less than 50 CHF, as that is our budget limit, but if it goes over, it’s not too bad.

Thank you for the quick replies. I wanted to clarify a few things that might help solve my problem.
My PC has a Line-Out port with a green ring, which is for audio output, and I want to connect it to a Sonos soundbar.
I also checked, and my PC only has 3 x 3.5mm audio jack connectors (green, pink, and blue). They are all analog and directly connected to the motherboard. Other than that, I don't have any additional audio outputs.
The Sonos soundbar has a Toslink (optical) input.




Pictures that might help:

Green Line-Out port on the PC:

Toslink input on the Sonos soundbar:

 

[Markw4]

AUX is not the name of a standard connector on a PC. That's why you haven't gotten any help. Nobody knows what you're talking about.

Is it an input, an output? Is it analog, digital? Is an RCA connector, something else? Is on the motherboard, on a sound card, something else? Etc.

 

[newvirus2008]

Assuming AUX means auxiliary line level audio input, here is a chip that is known to output an IEC-60958 stream.
https://www.ti.com/lit/ds/symlink/dit4192.pdf

For a complete schematic, see
https://www.ti.com/lit/ug/sbau124/sbau124.pdf

To obtain optical output you'd need to add a TOSLINK transmitter following the S/PDIF chip. For a list of suitable parts, refer to the page 5 of the following:
https://en.everlight.com/wp-content/uploads/2021/02/Application-of-PLT-and-PLR-on-SPDIF-V1.0EN.pdf

 

[Markw4]

If AUX is an analog input on the PC, then how can the OP drive his soundbar optical input with that? Maybe AUX is reconfigurable to an analog output?

Anyway, some sound cards and or some MBs have a spare SPDIF output on the board. Might be worth checking that first?

 

[pboser]

Assuming the computer output is a line-level analog audio output, what you're looking for is a ADC (analog to digital converter), the opposite of a DAC. I don't know of a diy project, but they can be purchased for a range of prices. Here's a cheap one on Amazon: https://www.amazon.com/Digital-Converter-Optical-3-5mmAUX-Soundbar/dp/B09Y9CGT56/ref=asc_df_B09Y9CGT56?tag=bingshoppinga-20&linkCode=df0&hvadid=80195759886248&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583795279385462&psc=1

 

[uriy-ch]

I suspect your computer has a USB output. To get an optical SPDIF output, it is enough to use this product or something similar.

 

[newvirus2008]

If AUX is an analog input on the PC, then how can the OP drive his soundbar optical input with that? Maybe AUX is reconfigurable to an analog output?

Well, according to the OP, the PC only has an AUX output ... so that should do ..

I found an old Sonos soundbar ...but unfortunately it only has an optical input and my PC ... only has an AUX output.

 

[theAnonymous1]

Digital (PC as source) -> analog (PC out) -> digital (some ADC to S/PDIF) -> analog (soundbar internal DAC) is a lot of extra steps for no reason and won't give optimal results.

I would recommend something like a PCM2906C to do USB to S/PDIF

 

[Markw4]

Pictures that might help...

What might help more would be to know the make and model of the computer and or of its motherboard. That may lead to possibly better solutions for driving the soundbar.