CAD Drawings

I have 25 hand drawn drawings that I would like put into an electronic CAD format. Whatever the standard format is would work the best for me. If they are also in a format that can be read using at least a free reader that would help so that I can review them. As you can tell I am not an expert at CAD. I have attached a sample of the most complicated drawing. They vary in difficulty and detail, but the rest are far more simple than the on attached. Larger, more high resolution scans are also available.