Hi,
I am planning to buy an PC based USB oscilloscope from picotech. And i am concerned about how to prevent from blowing all three (1) My Laptop(to which i will connect my oscilloscope through USB) - Dell Inspiron N4110
(2) USB oscilloscope
(3) My board >Pandaboard which i aim to probe. I will power pandaboard with AC to DC adapter(5V-2A output, having 2 pin, no earth pin).
I saw Dave's video "EEVblog #279 - How NOT To Blow Up Your Oscilloscope!". Also read the post "Test Equipment / Interface Isolation on Entry Oscilloscopes? (+USB Scopes, A Hard Lesson Learned)". I tried to add in same post but it said its >120 days old so i made a new post.
So my question as given below
"Suppose i remove my laptop charger. Now according to me laptop is powered by battery and its ground is not connected to earth ground. Then i connect usb oscilloscope to PC. Pandaboard is connected to adapter as mentioned above. Now i start probing the board. If by mistake i touch probe ground to a point on board which is not ground & has some voltage level, but circuit will not complete through earth ground because my laptop is not connected to earth ground, and nothing will blow up".
So what i could conclude that disconnecting the laptop charger should prevent the devices from blowing because low impedance circuit through earth ground is not complete.
I request experts to review this conclusion since i am a newbie.
Also in the above post("Interface Isolation on Entry Oscilloscopes?"), there is a mention of differential probes. Does differential probe prevent the devices from blowing ? Again i need expert advice.
- Abhay