Comment by mindcrime

A few come to mind, over the course of my childhood up to and including high-school.

The "Mad Scientist's Club" series

The Great Brain

Those "Encyclopedia Brown" stories

The "The Three Investigators" series

The Mysterious Island by Jules Verne

The original Doyle "Sherlock Holmes" canon

The Soul Of A New Machine by Tracy Kidder

The Lord of the Rings by Tolkien

Nineteen Eighty Four