fischertechnik ROBO STARTER Begleitheft Seite 19

R O B O
Lens Tip Bulb
A lens is a part of this light bulb and this focuses the light. It looks very much like the domed light so
that you have to watch out and don't mistake these. To make it easier to see the difference, the plug
base for this bulb is gray, but the domed light has a white plug base. You need the lens tip bulb to build
a light barrier. Technical data: 9V
Phototransistor
You can also call the phototransistor a "brightness sensor." This is a "detector" that reacts to brightness.
For a light barrier this is the counterpart to the lens tip bulb. When there is a high degree of brightness,
that is when the transistor receives light from the lens tip bulb, it conducts electricity. If the light beam
is interrupted, the transistor does not conduct any electricity.
Caution: When connecting the phototransistor to the power supply, you must pay special attention to
the right pole: red = plus.
Sensing Device
The sensing device is also called a touch sensor. When you press the red button, this moves a switch
mechanically and electricity flows between the contacts 1 (center contact) and 3. At the same, the
contact between the connections 1 and 2 is interrupted. So you can use the sensing device in two
different ways:
As a "closer"
Contacts 1 and 3 are connected.
When the button is pressed electricity flows.
When the button is not pressed, no electricity flows.
As a "opener"
Contacts 1 and 2 are connected.
When the button is pressed no electricity flows.
When the button is not pressed, electricity flows.
NTC Resistor
This component is a heat sensor that you can use to measure
temperatures. At 20°C, the resistance is 1.5kΩ (kilo ohms). NTC
stands for Negative Temperature Coefficient. This simply means that
the resistance value decreases when the temperature increases.
The information, which the sensors supply to us such as bright-dark, pressed-not pressed, and
temperature value, can be, as you will see later, passed to the PC through the interface and then with
the help of the software, for example, you can program a motor to open a door as soon as the light
barrier is interrupted.
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Before you get started
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