Chapter 4. Contact Sensors
Contact sensors are the simplest NXT sensors because they're only on or off. The LEGO Touch Sensor is a good example of a contact sensor. Homebrew contact sensors use the same NXT-G Touch Sensor block shown in Figure 4-1 as the LEGO ones. You probably already have everything you need to homebrew one. Even if you don't, the parts are readily available from electronic stores such as Radio Shack, and even from hardware stores.
Figure 4-1. NXT-G Touch Sensor block
We've already covered many methods for connecting to the NXT sensor inputs in Chapter 3. For contact sensors, we're interested in only two of the six possible connections. ...