3T circuits 5.4

• Natuurkunde
• Middelbare school
• vwo
• Leerjaar 3

Homework from last time

2, 3, 5, 9 & 13

Components & functions

• The sensor produces an electrical signal with information about the surroundings. 
• The switch responds to the signal of the sensor (for example by switching power on/off)
• The actuator does does something that is needed according to the switch.

An example

Sensor

Actuator

Electric motor

LDR (Light Dependent Resistor)

LED light

NTC

Buzzer

But how does it work?

The actuator is often just an electrical component.

But what is the switch???

But how does it work?

The actuator is often just an electrical component.

But what is the switch???

Transistors!

The transistor

The transistor

When a small currrent flows from the base to the emitter, a much larger current can flow from collector to emitter.

The transistor is now in the ON position.

The transistor

When no current flows from the base to emitter, no current can flow through from collector to emitter.

The transistor is now in the OFF position.

Burglar system

Burglar system

Glass window

(sensor)

Buzzer

Transistor

Resistors

Burglar system

Burglar system

Working yourself

First see if you can understand the automatic streetlight (p. 99)

Then work on exercise:

4, 5, 7, 8

If you're done, then try 6