Hi all, I am a total novice and I was given one of these to encourage me to learn about Electronics and am making good progress. However. I see a Yellow trace = Channel 1. A Blue trace = Channel 2. But I also see (sometimes) a Red trace. I have searched the User Manual and several forums and I cannot see any reference to a Red trace. Now obviously it is something which is blindingly obvious to anyone with half a brain. Unfortunately I cannot for the life of me see what it is. Could someone put me out of my misery please?