06/06/2014 22:11
5. Electronic control systems:
Control systems are able to carry out increasingly complex operations.
Many of these sytems consist of just electronic elements.
5.1.Transistors as control systems.
When we want to detect one physical parameter with the purpose of carrying out an action we can use circuits with transistors.
-The physical parameter could be, for example pressure.
-The response could be to switch on an alarm.
Sensors are devices that detect the physical parameter.
-Basic control circuits using transistors
Using transistors we can control the components of an automated system that needs more power, i.e relays and motors.
5.1.1.Control of a relay
When we connect positive and negative energy to the circuit, then push the switch, the relay activates, and the energy flows trough the motor, and the circuit works.
5.1.2.Control of a motor
In this circuit the sensor is the LDR. That means that depending on the ammount of light the circuit will work or not.
If there is a lot of light the resistance decreases and the transistor gets energy on the base closing the circuit and making the motor work, the diode works as a protector. Also if the screw of the potentiometer is rotated the resistance of the potentiometer changes, varying the intensity of the motor.
