Gold

What am I Looking At?
« on: January 15, 2018, 01:29:26 PM »
I thought a general topic on how to measure, what to measure and how to know what you are looking at when you do measure would be useful. I know it has taken me a long time to gain some proficiency with my test equipment. Just getting around on an oscilloscope can be challenging for a non electronics person.

Here is my question of the day. Often when I look at the positive and negative legs of a balanced output, the level on each leg looks different. Yet everything works as expected level wise when feeding  a balanced input. Why?


JohnRoberts

Re: What am I Looking At?
« Reply #1 on: January 16, 2018, 11:15:14 AM »
Because there are a number of ways to skin that output circuit cat...

Only a center tap grounded output transformer, and active differential (not active balanced) will deliver the same voltage (polarity inverted) to both legs.

If the transformer is floating, or using active balanced outputs, the signal on individual legs can vary with loading.

The net voltage difference between the + leg minus the -leg , should always remain stable.

JR
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Gold

Re: What am I Looking At?
« Reply #2 on: January 16, 2018, 06:40:47 PM »
Because there are a number of ways to skin that output circuit cat...

Only a center tap grounded output transformer, and active differential (not active balanced) will deliver the same voltage (polarity inverted) to both legs.

If the transformer is floating, or using active balanced outputs, the signal on individual legs can vary with loading.

The net voltage difference between the + leg minus the -leg , should always remain stable.

JR

Thanks, that solves the mystery for me.