Use BNC Cable to ADC in Teensy

[hsPark]

Hi guys, I'm doing a project in graduate school which uses AD converting and get analog signals with BNC Cables. I'm going to save data to the computer as text files. Actually, analog signals are neural signals(which is voltage up to 300 micro V)

Problem 1.

As I cut the BNC cable, there are two cables, red and black.

Where should I connect these cables to get analog signals in teensy board?

Problem 2.

After getting the analog signal, how do I write that data? measure frequency is 50k Hz.

Thank you

[GypsumFantastic]

I'd normally expect BNC connections to be coaxial - a core and a shield, so I'm a bit confused by your description. Maybe post a photo?

In any case, you won't be able to connect the wires directly, because your 300µV signal will be too tiny for the teensy to detect.

The Teensy has (I think) 10 bit ADCs so it can differentiate 1024 analogue levels.

Even with the minimum allowable external reference voltage (it's about 1 volt I think) the smallest voltage the ADCs can detect is approx 1mV (3 x larger than your max signal).

This means you'll need an analogue signal amplifier to bring your tiny signals into the teensy's workable range.

[hsPark]

I forget one thing important. Sorry. We use Amplifier. Then we connect BNC and Teensy.

[TomGeorge]

Hi,
Can you post a picture of your BNC cable and its plug?

Thanks.. Tom..

[hsPark]

Hi,

Here is the picture that BNC cable and Teensy 3.6 Board

open the image in new tab

[TomGeorge]

Hi,
Sorry, you need to attach it.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html

Use REPLY rather then QUICK REPLY, you will find an attachment facility.

Tom..

[hsPark]

Hi, sorry for bothering you.

Here is the photo.

Thanks. Park

[TomGeorge]

Hi,
Thanks for the picture.

Although a close look at either end would have helped.
Can you use a DMM and using continuity, check what the two wires are connected to in the plug?

Thanks.. Tom..

[hsPark]

Hi,
Thanks for the comment.

First BNC cable (picture 1) end is connected to the amp, and get the amplified signal.

And I want to connect another end of the cable(picture 2, red and black) at teensy 3.6 Board to transmit the signal to the board.

I want to get waveforms of data, collected at 50kHz,which is not continuous.

[TomGeorge]

Hi,
OPs pics

Okay so its unshielded cable.
Please check with a DMM that;
The RED wire goes to the BNC plug pin.
The Black wire goes to the BNC plug body.

Can you tell us your electronics, programming, Arduino, hardware experience?

Thanks.. Tom....
DMM == Digital Multimeter

[hsPark]

Hi,

Actually, it's my first time of arduino coding, and, I have no experience about hardware experience.

But, I have little experience with electronics and programming.

It's my first task in a lab. I want to do it successfully.

Sorry for bothering you again.

Thanks. Park

[jadkh]

Hello Everyone! I know it's been a long time but I need help with the same topic
HSpark, did you find a solution connecting the BNC plug to the Teensy's ADC ?
Thanks

[Paul_B]

It's almost certain that the black wire goes to ground and the red wire goes to the ADC pin.

Apart from that, perhaps you should explain what you are actually doing.

[TomGeorge]

Hi, @jadkh
Welcome to the forum.

Please read the post at the start of any forum , entitled "How to use this Forum".
OR
https://forum.arduino.cc/index.php?topic=712198.0

Thanks.. Tom...