Subsystem: IP1

Task Title:
Light to Voltage Converter
Potential/Voltage Dividers
and Sensors


Introduction and Aims

In this starter project, we will be modelling a potential divider circuit. With the help of a multimeter, we will show how the output voltage can be made to change as we vary the amount of light falling on its input light sensor (Light Dependent Resistor - LDR).
Note - A potential divider circuit can be made up using other sensors. These can, for example, detect heat, touch, moisture and angles.

 


SubSystem Circuit and Block Diagram

 

IP1
Light Sensor
OP1
 


Investigating the System

First open the "Library of Subsystems" here and search for "IP1 Potential Dividers". Read the description given and then using the circuit and block diagrams above, complete the following:

1, The LDR symbol has arrows to show the light. These are pointing the LDR.

2, The resistor with an arrow through it, can have its resistance value varied: this will change the voltage across it. In the circuit diagram a is connected in parallel with it.

3, A light sensing system is used by street lights to....
.

4, The input or supply voltage from the battery is equal to the voltage across the LED added to the voltage across the which is connected in series with it.

Modelling the System/Circuit

There are different ways to model and test circuits before components are soldered to a P.C.B.. Modelling is an important stage as it helps you spot any problems and make modifications more easily.

Method 1: Breadboard

Using this method, components are pushed into the interconnected holes as shown in the diagram below. The lines shown, indicate which holes are internally connected.

Print this page and by using the circuit diagram above, design the breadboard layout for this system.

Method 2: Computer Simulation

To begin, ask your supervisor if circuit simulation software is available on your PC. This method allows you to build up your circuits quickly and cheaply in a virtual environment but will not give you hands-on experience of the components you will be using when finally soldering your P.C.B..

Method 3: Using OnTrack modelling hardware

See IP1 project guide.