The vehicle is capable of moving in two directions i.e, front and back. This has been implemented by the use of relays. Depending on which signal has been activated by the incoming transmission, from the computer parallel port, the car moves in the desired direction.
The Car.
Relay Logic :
Relay and Motor Connections.
From the above picture we see that the
normally open connections are connected to the power supply for the motor.
The normally closed contacts are connected to the ground.
The working is as follows. When relay 1 is activated, A gets a positive from
the normally open contact of relay 1 and B gets ground from the normally closed
contact of relay 2. When relay 2 is activated, A gets ground from the normally
closed contact of relay 1 and B gets positive from the normally open closed
contact of relay 2.
In other words, when relay 1 is activated, the motor gets one type of polarity
and when relay 2 is activated, the motor gets the opposite polarity. This
way the car is able to move in one direction when relay 1 is activated and
in the other direction when relay 2 is activated.
Power Supply :
The car requires only one power supply
to drive it. We have used only a 3Volt supply to power the car. Since it uses
relay logic, we do not require the use of different supplies for the different
directions of the motion of the car.
This in effect reduces the power overhead which has to be carried by the car.
Reed relays can be used if very less power is available to power the relays.
Since reed relays are very sensitive electromagnetic relays, it requires very
less current of the order of 15mA to power it.
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