Dacta (the educational division of LEGO) has a number of sensors available
as part of their science and technology products. In addition, the #8479
Barcode Truck set contains a new version of the touch sensor. It looks like
all of these sensors are compatible with LEGO's new Mindstorms product,
though it remains to be seen if LEGO will start to offer any sensors as
S@H service packs. Presently, the only ways to purchase individual sensors
is through Pitsco, the single distributor of Dacta products. The sensors
fall into two categories: passive (a resistance is measured), and active
(the device consumes power). All of the dacta sensors have built in leads
that terminate in the standard 2x2 electrical plate. The new touch sensor
requires a separate lead. The various sensors are listed below:
- Touch Sensor (dacta): This passive sensor is simply a normally open
switch built into a 2x4 brick. Pitsco sells this as #779888 for $18.
- Temperature Sensor: This passive sensor is a thermistor (temperature
sensitive resistor) built into a 2x3 brick, with the sensor extending about
3 units from the brick. Pitsco sells this as #979889 for $27.
- Light Sensor: An active sensor that includes an LED and a phototransistor
built into a 2x4 brick (I believe the brick is actual 1-1/3 units high).
Information from Mindstorms indicates that the sensor can be used to either
detect incident light, or detect reflected light from the LED. Pitsco sells
this as #979890 for $27.
- Angle Sensor: An active sensor that includes an optically coupled quadrature
detector built into a 2x4 brick (2 units high?). The resolution of the
detector is 1/16 of a rotation (22.5 degrees). Available from Pitsco as
#979891 for $27.
- Touch Sensor II: Introduced with the Barcode Truck, this sensor is
similar in function to the original touch sensor, except it is a 2x3 brick
and requires an external lead.