Subsystem: OP3

Task Title:
Vehicle Safety System

Relay Driven Outputs


Introduction and Aims

To model a system that will reverse a motor when a light beam is
interrupted (Note - this could be part of an automatic vehicle's safety or steering system).

Subsystem Circuit and Block Diagram

IP1
Light
Sensor
P2
Darlington
Pair
IP3
-going
Switch
Trigger
OP2
Motor
Driver
OP3
Relay
DPDT

 
Sub System 1
IP1 and P2 make a Light /Dark sensor that controls the switching of the relay (see subsystem P2).
 
Sub System 2
OP2 produces a low voltage power source, to drive the motor. When the push switch on IP3 is pressed the power is available (see circuit diagram in links above).
 
Sub System 3
Relay module P3 reverses the polarity or connections to the motor (see circuit diagram in links above).This reverses the direction of the motor.


Investigating the System

Using the "Library of Subsystems" here and the circuit and block diagrams above, complete the following:

1, The relay could be described as an electrically/ mechanically operated .

2, The voltage needed to operate the relay can be much less than the voltages used in the output part of the relay. This relay can switch output devices operating at volages up to volts.(see OP3 Relay Outputs)

3, To make the motor run in reverse, the relay is used to the two wires going to the motor.

4, The diode connected across the relay is used to remove dangerous produced by the motor.

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 OP3 project guide.