I picked up a "Three Fives" Discrete Timer Kit this weekend. As it turns out the kit was well worth the money. The "Three Fives" Discrete Timer Kit is a transistor-scale replica of the NE555 timer IC. The printed circuit board (PCB) is high-quality and soldering the transistors and resistors was alot of fun. Thanks to Eric Schlaepfer and Evil Mad Scientist Labs for this high quality circuit kit.
The size of the board makes it easy to measure what's going on inside the circuit. Just connect the probes from an oscilloscope to any of the solder or test points on the board.
A photo of the board that I built is below. I also wired a sample test circuit for blinking a pink LED and then connected a scope to the board so that I could look at the square wave.