Pico Scope Circuit test using Ohms and Watts Law

Now I know this test will not be for everyone as we all have different processes and tooling to carry out the same tests but I hope this can show good use of Ohms/Watts law using the Pico scope to test a complete circuit using just Battery voltage on Channel 1 and Amps on Channel 2 and takes less than a Minute to set up.

Once you have the 2 channels hooked up for volts and amps you need to create 2 maths channels to calculate Ohms Law and Watts law

Click the tools tab(pictured) then select ‘maths channels’

A window will open which has some built in maths channels to select from , we are going to use A*B and A/B

This will give us 2 extra channels – one will use Ohms law to graph channel A(volts) divided by Channel B (current) equalling Resistance

The other will show Watts law using volts times current equalling power(in watts)

Now when you click start you should have 4 channels instead of 2 and it will now do all the maths for you !!!!

The Next picture shows a lighting circuit being switched on and then off again so we are testing a loaded circuit and can now see Volts ,Amps ,Resistance and Watts

In this we can see only 11 watts which is very low for a headlamp circuit and also 13 Ohms of resistance which is high for this circuit(enough to stop the lamp illuminating) , also a very low amp draw.

That’s 3 valuable measurements for any circuit and now gives good reason to look for a resistance in the circuit.

The last picture shows the result after removal of an 11 0hm resistance , Resistance is down to 2 ohms , power is fully restored(watts) and an expected current is flowing again.

Imagine you find a 5 ohm resistance in one wire – You know there is still another resistance in the circuit which can save some head scratching later on!!

Hopefully you can find a use for this and it helps along the way , It can be used in so many applications (actuator circuits , lighting , etc )

Glenn Norris CAE AMIMI

Definitive Diagnosis