CONTROLLER CIRCUIT PART
PIC 16F877A
The pin RB0-RB7, RC0-RC7, and RD7 are digital l/O pins,
while pins AN0-AN7 are for analog I/O.RA0-RA5 and RE0-RA5 RE0-RE2 are also
ports, but with fewer pins. Some of these pins have special purposes, but mot
can be used as basic input/output pins. For example, you can set pin RBO to be
either an input pin, or an output pin. As an input pin, the digital voltage on
the pin can be read in. For example, if RBO is connected to ground (0v), then
you would read a digital 0 If RBO was connected to power (5v), then you would
read a digital 1. On the other hand, if you wanted to set RBO as an output pin,
you could choose to make RBO either be 5v, or 0v.This can be used, for example,
to turn off or on a LED, or to turn off or on a motor.
OPTOISOLATOR AND TRIAC SWITCHING
TRIAC,
from Triode for AC is a generalized trade name for an electronic component
which can conduct current in either direction when it is triggered (turn on), and is formally called a bidirectional triode thyristor or bilateral triode
thyristor. When used with inductive loads such as electric fans, care must be
taken to assure that the TRIAC will turn off correctly at the end of each
half-cycle of the AC power. An
optoisolator, also called an optocoupler, photocoupler or optical isolator is
an electronic device designed t transfer electrical signals by utilizing lights
waves to provide coupling with electrical isolation between its input and output. The main purpose of an optoisolator is to prevent high voltages or
rapidly changing voltages on one side of the circuit from damaging components
or distorting transmission on the other side.
INDUCTOR
When
current 1st starts flowing in the coil, the coil wants to build up a
magnetic field. While the field is
build, the coil inhibits the flow of current. Once the field is built, current
can flow normally through the wire. When the switch gets opened, the magnetic
field around the coil keeps current flowing in the coil until the field
collapse. This current keeps flows for a period of time even though the switch
is open. In other words, an inductor can store energy in its magnetic filed,
and an inductor tends to resist any change in the amount of current flowing
through it.
The inductor opposes
changes in a variable in the circuit. The indictor likes to maintain a constant
current.
The triac switching unit described here is the same basic design used in many solid state relays (SSR). The center of the circuit is the MOC3042 or MOC3041 opto isolator. The difference between these parts is the current required to trigger the internal LED. The resistor limits the current from the cap into the opto isolator and causes the LED to illuminate inside the chip. Line voltage flows through the 360 ohm resistor and into the zero-crossing circuit in the opto isolator. When the zero-crossing circuit detects a zero crossing voltage and the LED is illuminated, the gate on the triac in the optoisilator is triggered with the same phase as the phase of the line voltage. This line phase current is then used as the gate trigger to the alternator. This causes the line current to flow through the alternator and power the load. This circuit only works if line current is fed into pin 6 of the opto isolator. If the circuit hooked up wrong, the zero-crossing circuit will not detect the voltage zero crossing and will not trigger the alternator. A common mistake in this circuit is to take the series gate resistor too large in value. The circuit also builds with LC circuit that acts electrical resonator. It’s also known as resonant circuit or tuned circuit. Its can stores electrical energy oscillating at its resonant frequency. The capacitor stores energy in electric field by depending on the voltage across it and inductor stores energy and its magnetic field depending on current that flows through it. This circuit will be a key component in circuit application for oscillator, filter, tuner & frequency mixer. The main purpose of this circuit is to do oscillation with minimum damping.
CONTROLLER CIRCUIT OPERATION
The triac switching unit described here is the same basic design used in many solid state relays (SSR). The center of the circuit is the MOC3042 or MOC3041 opto isolator. The difference between these parts is the current required to trigger the internal LED. The resistor limits the current from the cap into the opto isolator and causes the LED to illuminate inside the chip. Line voltage flows through the 360 ohm resistor and into the zero-crossing circuit in the opto isolator. When the zero-crossing circuit detects a zero crossing voltage and the LED is illuminated, the gate on the triac in the optoisilator is triggered with the same phase as the phase of the line voltage. This line phase current is then used as the gate trigger to the alternator. This causes the line current to flow through the alternator and power the load. This circuit only works if line current is fed into pin 6 of the opto isolator. If the circuit hooked up wrong, the zero-crossing circuit will not detect the voltage zero crossing and will not trigger the alternator. A common mistake in this circuit is to take the series gate resistor too large in value. The circuit also builds with LC circuit that acts electrical resonator. It’s also known as resonant circuit or tuned circuit. Its can stores electrical energy oscillating at its resonant frequency. The capacitor stores energy in electric field by depending on the voltage across it and inductor stores energy and its magnetic field depending on current that flows through it. This circuit will be a key component in circuit application for oscillator, filter, tuner & frequency mixer. The main purpose of this circuit is to do oscillation with minimum damping.
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