Ok, to start off, I know how to read a schematic, and I'm familiar with how to build a circuit. I'm just not knowledges on creating either of those mainly because I'm not familiar with the 1000's of IC's and other special components and functions. But I will post what I want and see if I can get some help. I want a circuit where I can replicate what another wire has running through it without adding or lowering the resistance of the original circuit. Say there's a wire running 12V/30A and it's pulsing this voltage at various frequencies. I want to cut that wire, run it into a circuit, and out of that circuit and the generator of the original circuit not have any more or less load, and the receiver still get the same circuit. Basically I have a motor doing its job, I want another motor to work identically as the first. But I will also want the strength of the second motor to be adjustable on the fly. I am working with 12V DC circuits. And yes, it will be going in my car. Sometimes we want to add more to our cars electronics than they can handle. And this is one case. But I'm a do it yourselfer who wants a simple part that does what I want without any excess features, nor do I want it mass produced over seas. Thank you for your help.