Extreme NXT: Extending the LEGO MIDSTORMS NXT to the Next Level is for intermediate-level users of NXT who would like to advance their capabilities by learning some of the basics of electronics. Plenty of examples are provided, and easy-to-follow instructions are included for building over 15 different sensors.
I had never soldered any electronics before, so I started with a simple project as described on the Extreme NXT website. The solder instructions in the book were very helpful.
Combined with the Mindsensors sensor sockets, it resulted in this:
The sensor works quite well. I’ve used some tape to cover the sides of the LEDs (not in this photograph) so that the photocell would only measure the reflected light from the surface.
Below is a video of a basic line follower with the sensor. First I calibrate the sensor by telling the robot what is white and what is black.
If you like to expand your knowledge of electronics and the NXT kit, I would really consider to buy the book.