Hi,
Why don't you just buy a true RMS meter? It would be a lot cheaper than a scope.
It won't give useful results:
Some values:
Let's assume you use a LED, specified with 1A, 10V. It will be completely OFF (no current) with 8V
Now let's assume the LED current is DC 1A.
--> the RMS meter shows 1A, and 10V
--> an average meter shows 1A, 10V, too.
LED power is 10W.
Now let's assume the LED voltage is 8V/10V and thus the current is 0A/1A, 50 % duty cycle.
The LED power is 5W
--> the RMS meter shows 0.707A, 9.05V, ...how do you calculate the 5W?
--> the average meter shows 0.50A, 9.00V, ...how do you calculate the 5W?
Now let's assume the LED voltage is 0V/10V and thus the current is 0A/1A, 50 % duty cycle.
The LED power is 5W
--> the RMS meter shows 0.707A, 7.07V, ...here you can calculate 5W
--> the average meter shows 0.50A, 5.00V, ...how do you calculate the 5W?
--> you need a true V(t) x I(t) multiplying power meter = active power meter
Klaus
Added:
Too late...others recognized the same during me writing the post.