• 0
Eric

Loop created when using both scope channels with Discovery 2

Question

Hi all,

I've run into an unexpected problem.    

Issue

It seems that when I use both scope channels within the same circuit (at least for this circuit) I get tons of 60Hz noise and its harmonics.  Using a single channel does not generate this kind of noise.

Setup

I am using a 3 channel DC supply plugged into 60hz wall power that feeds my breadboard circuit in two areas.  My breadboard circuit is a simple non-inverting op-amp whose input signal comes from a constant current source excited thermistor.  The gain is ~ 30 V/V.    I'm using the Analog Discovery 2.

Details

Normally, I've been using the either channel to check my pre or post-amplified signal.  This single channel behaves normally.  Nice low frequency temperature response from my thermistor.

However, upon adding the other channel to look at the opposite end of my op-amp circuit, I get tons of 60Hz, 120Hz, etc. garbage.

Advice?

 

Regards,

Eric

Share this post


Link to post
Share on other sites

2 answers to this question

Recommended Posts

  • 0

Hi Dan,

True,  I did not have the Discovery's ground hooked in.

Seems like I've confounded the issue now, however.  The single channel response has become way more garbled and I'm getting some inconsistent readings.  I feel like I've messed something up.  Will return when results are reproducible.

 

Thanks,

Eric.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now