Hi, I'm sorry if this is not the right area. I'm new to this, but I got my hands on a TDS210 and my first project is to build a power up cycle current limiter for a set of power amplifiers. I need help in figuring out how to measure power line noise levels. The project: This project is related to my home theater. The amplifiers, three Rotel 1090, have huge transformers and the power up cycle of these beasts toast up the voltage regulator, a Monster Power AVS2000. I have a couple replaced already (at no cost by MonsterCable). The idea to solve this problem is very simple. Put just put a huge resistor 300W 20 ohms in series so to limit the power up cycle to some 3-6 amps and use solid state relays to bypass the resistor after 2-3 seconds when the current demands are more reasonable. In actuality I'm using 2 relays, a time delay solid state relay of 10 amps that triggers a high current solid state relay of 75 amps. The later is the one that bypasses the resistor. The idea is that the second relay at 75 amps will provide the amplifier with better dynamics than a regular time delay ssr rated at 10 amps. All of this times three (one circuit per amplifier). That is the part I think I have figured out. The problem: I would like to be able to measure the "noise" of the power line. Besides the voltage stabilizer (AVS-2000) I'm also using line filters (HTPS-2600). I want to be able to measure how clean the power is at several parts of the circuit and see if my modifications are introducing any noise and also see how well the equipment is filtering out the garbage that comes in the power line... may be this is more of a curiosity, but I'm eager to see this stuff measured. The short version: so I got my hands on this TDS210 oscilloscope from Tecktronics. The probes that come with it are general purpuse passive 10X and I fugure how to use the scope to measure low voltage AC stuff. However when I hook the probe to the wall outlet they don't seem to be measuring anything. I'm new to this... do I need different probes? Am I missing something? Once I get a reading off the regular power line (assuming we figure what I am doing wrong) how do I identify and measure the "noise"? I presume I'll need a data capture interface. which seems to be going for $350. But if in addition to that I need new probes then things start to get ugly. So, as you probably noticed I do not have much of an education on this electronics stuff. I'm trying to find/fight my way around it. Can you help me measure power line noise levels? Thanks!