Electronics > Projects, Designs, and Technical Stuff

world's most shielded cheapo USB sound card: 100g copper

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ChristofferB:
I'm getting a NIM bin full of nuclear/particle measurement modules!! Hype! Multiple shaping amplifiers, spectroscopy amplifiers, gate stretchers, HV bias etc.

I want to mess about with a PMT and some gamma-spectroscopy but it seems the rack is missing the ADC and/or multichannel analyzer. Bummer.

There are quite a few different "sound card multichannel analyzer" software packages available for free, and I figured using proffessoonal amplifiers/shapers for all teh low level stuff might make it a pretty decent-ish system until i crack and spend all my money on an actual MCA.

I was worried about digital noise from the laptop making its way back so I decided to provide some additional noise reduction measures. I wanted a BNC on the sound card dongle anyway so.. Here is a very copper shielded 10$ USB sound card!

Is it going to matter at all? I'm not convinced but at least it looks fancy. The IC foam is a bit silly in this application, the thought was for it to act as an absorber in case some overtones of the digital signalling found a resonance mode in the can.

Either way, I'm at least pleased with the visuals  ;D

--Chris










rwgast_lowlevellogicdesin:
I think it looks cool, not sure if that is necessary if your only viewing the audio spectrum though :). Why not stick a thermo-electric cooler on it, that way you can minimize the the johnson noise from the resistors! Seriously though it looks a lot more like gear now instead of consumer electronics from china, definatly thinking of doing this for the bling value! :)

magic:
That's some tweaks worthy of a serious audiophile, that piece of anti-static foam thrown inside is the best :-DD

But seriously, "computer noise" usually means ground loops and you can't do much about it without galvanically isolating USB.

And speaking of ground, those cheapo cards usually use virtual ground at something like 1.6V. So don't connect their analog I/O "grounds" to a real earth ground while the computer is grounded too.

ChristofferB:
..Yeah it went a bit more towards style points than use point  ;D All I really wanted was a BNC instead of a 3.5mm jack.

Good to know with the virtual ground! I'm pretty sure the audio ground was connected to the USB ground and shield though. Something to watch out for.

Yeah the foam is completely useless in this setup, but if nothing else it will confuse future me when i open the tin in 10 years  ;D

The humongous can for the tiny board is mainly so I can re-use the can for other things, and make modifications. A few of the 'sound card MCA' papers I found adds a passive LPF of different kinds at the input. Physicists are rubbish at explaining electronics satisfactorily, though. One of the MCA papers was about the construction of a microcontroller based MCA. The paper had a block diagram, no circuit, no code, and no supporting information..

magic:

--- Quote from: ChristofferB on January 09, 2020, 10:38:12 pm ---Good to know with the virtual ground! I'm pretty sure the audio ground was connected to the USB ground and shield though. Something to watch out for.

--- End quote ---
Maybe you found a better one. I had two and both used virtual grounds |O

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