Page 227 - The Unofficial Guide to Lego Mindstorms Robots

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11
Make Your Own Sensors

In this chapter:

• Mounting

• Passive Sensors

• Powered Sensors

• Touch Multiplexer

• Other Neat Ideas

• What About Actuators?

• Online Resources

If you're not afraid of a soldering iron, you can create your own robot sensors. Although you can buy the ''official" sensors
from the LEGO online store or LEGO DACTA (see the Appendix A, Finding Parts and Programming Environments), there's
not a very wide selection. Furthermore, they are expensive—$10US for the touch sensor, $20US for a light sensor, $15US for
the rotation sensor, and $25US for the temperature sensor. Building your own sensors is a great way to expand your robot's
capabilities without spending a lot of money.

This chapter describes different ways of fitting sensors into LEGO bricks, provides discussions of various types of sensors you
can build, and considers some innovative possibilities for putting multiple sensors on one RCX input.

Mounting

The first thing you should think about is how you are going to attach your new sensors to the LEGO world. There are two
goals to consider here:

1. The sensor, ideally, should be a LEGO brick itself so you can easily attach it to your robots. The sensors that come with RIS
exhibit this property: the touch sensors and the light sensor are simply specialized bricks.

2. The sensor needs to connect electrically to the RCX. Somehow the electrical connections from the sensor circuit will need to
mate with the RCX's input connections. There are four basic approaches—cut wire, copper tubing, machine screws, and a
conductor plate—which are described in the following sections.