07-08-2012, 11:59 AM
Transformer
1Transformer.pptx (Size: 52.44 KB / Downloads: 44)
POWER SUPPLY :
They are designed to convert high voltage to low voltage ac mains.
It is broken into series of blocks they are,
Transformer- steps down high voltage to low voltage.
Smoothing – smoothes the dc from varying ripple.
Regulator – eliminates ripple.
Rectifier – converts ac to dc .
RELAY DRIVER :
It’s an electro – magnetic switch.
Used to switch on and off.
Its is connected to a 220v main supply.
The current needed to operate is more than the chips.
So we use transistors .
RELAY :
A relay is an electrically operated switch.
Current creates magnetic field in the coil.
Attracts a lever and changes switch contacts.
They have two switch positions its on and off.
They mostly have double throw switch contacts .
Sudden collapse of the relay coil due to high voltage is protected by using protection diode.
PWM:
It is a device that may be used as an efficient light dimmer or dc motor speed controller.
This device has been used as a motor speed control for dc fans.
Main advantage of pwm is that pulses reach the full supply voltage.
SPEED SENSOR :
Speed of the dc motor is sensed by opto interrupter.
It consist of an IR emitting diode and NPN silicon phototransistor.
It is encased by an black thermoplastic housing.
The phototransistor receives radiation from IR only .
But when an object is in between that , it could not receive radiation.