why we need differential probes?

Thread Starter

ssonel1

Joined Feb 24, 2020
16
Hi all. I know we need differential probes for differential voltage measurements and single-ended for ground referenced voltages. But I couldn't find any resource that explains why it is like that. Maybe it is so simple but I can't see the reason.

Another thing that I want to ask is, can we use single-ended probe for low level differential voltage measurements, for example node-1 is 10V and node-2 is 15V. Can I connect ground probe of oscilloscope to node-1 and live probe to node-2? Is there any voltage limit for that?

Thanks in advance.
 

Tonyr1084

Joined Sep 24, 2015
5,091
Connecting the ground probe to node 1 could short out your power supply. The scope is grounded and if your power supply is also grounded then when you touch the ground lead to node 1 you're creating a direct short. You could damage the power supply. That in itself may answer your other question about why a differential probe is needed.
 

Reloadron

Joined Jan 15, 2015
5,646
I will give you one of the many uses of differential probes. I worked quite a bit with 480 VAC 3 Phase Delta 60 Hz as well as assorted frequencies of 3 phase delta. When I measured I normally used 3 channels measuring phase A to B, phase B to C and phase C to A. That simply is not going to happen without a good, high voltage differential probe. The probes we used were all Tektronix and active probes. Good stuff.

Now if you only have a single floating signal and two available channels with the right scope then you can do as suggested in post #4.

Ron
 
Top