Transciever Major Parts
1.
Resistor = to control or limit the current.
Makikita nyo sa picture, 12v na dumaan sa resistor, na limit nya ang current sa 3v
2.
Capacitor = ability to store electrical or voltage.
3.
Transistor = to enlarge, extend the signal.
4.
Diode = to rectify and detect the signal.
Rectify = to convert AC to DC.
what is RADIO
Radio = is an art of wireless communication.
1. Standard Radio
2. Output Transformer Less
Radio (O.T.L.)
Tube-Transistor = I.C.
(integrated circuit)
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Electronic Symbol
antenna
Antenna Coil
I.F. (intermidiate frequency) transformer
Ang I.F. transformer ay makikita nyo sa radyo na may kulay puti, yellow at black.
kung
makikita nyo ang signal ay lumabas na nakuha sa air, or radio station.
Ang ginagawa ng if transformer ,tingnan sa picture. Ay pinapaganda nya
ang tunog, mula sa 99% clear papunta sa 100% clear, papunta sa speaker
at maririnig na natin.
Oscillator
Coil ang kulay nya ay red.
Interstage transformer
Output transformer
Resistor
Thermistor
Volume control
Capacitor
Valuable capacitor
Diode
Battery
Ground
Speaker
Wire connected
Wire not connected
Transistor
Two kinds of transistor
1. NPN
2. PNP
1
. Block Diagram
2.
Pictorial Diagram
3.
Schematic Diagram
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1/8 watt - pinakamaliit - 1 ohm
1/4 watt - 1 ohm
1/2 watt - 1 ohm
1 watt - 1 ohm
10 watts - pinakamalaki - 1 ohm
What do resistors do?
Resistors limit current. In a
typical application, a resistor is
connected in series with an
LED:
Enough current flows to make
the LED light up, but not so
much that the LED is damaged.
Later in this Chapter, you will
find out how to calculate a
suitable value for this resistor.
Resistors
are used with transducers to make sensor subsystems. Transducers are
electronic components which convert energy from one form
into another, where one of the
forms
of energy is electrical. A light dependent resistor, or LDR, is an
example of an input transducer. Changes in the brightness of the light
shining
onto the surface of the LDR
result in changes in its
resistance. As will be explained
later, an input transducer is
most often connected along with a resistor to to make a
circuit called a potential divider. In this case, the output of the potential divider will be
a voltage signal which reflects
changes in illumination. Microphones and switches are
input transducers. Output transducers include loudspeakers, filament lamps
and LEDs. Can you think of
other examples of transducers
of each type? In other circuits, resistors are
used to direct current flow to
particular parts of the circuit,
or may be used to determine
the voltage gain of an
amplifier. Resistors are used with capacitors (Chapter 4) to
introduce time delays. Most electronic circuits require
resistors to make them work
properly and it is obviously
important to find out
something about the different
types
of resistor available, and to be able to choose the correct resistor
value, in , , or M , for a particular application. Up Go to Checkpoint .
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Diode
Function Diodes allow electricity to flow
in only one direction. The arrow
of the circuit symbol shows the
direction in which the current
can flow. Diodes are the
electrical version of a valve and early diodes were actually
called valves. Forward Voltage Drop Electricity uses up a little
energy pushing its way through
the diode, rather like a person
pushing through a door with a
spring. This means that there is
a small voltage across a conducting diode, it is called
the forward voltage drop and is about 0.7V for all normal
diodes which are made from
silicon. The forward voltage
drop of a diode is almost
constant whatever the current
passing through the diode so they have a very steep
characteristic (current-voltage
graph). Reverse Voltage When a reverse voltage is
applied a perfect diode does
not conduct, but all real diodes
leak a very tiny current of a few
µA or less. This can be ignored
in most circuits because it will be very much smaller than the
current flowing in the forward
direction. However, all diodes
have a maximum reverse voltage (usually 50V or more) and if this is exceeded the
diode will fail and pass a large
current in the reverse direction,
this is called breakdown . Ordinary diodes can be split
into two types: Signal diodes which pass small currents of
100mA
or less and Rectifier diodes which can pass large currents. In addition
there are LEDs (which have their own page) and Zener diodes (at the
bottom of this page). Connecting and
soldering Diodes must be connected the
correct way round, the diagram
may be labelled a or + for anode and k or - for cathode (yes, it really is k, not c, for
cathode!). The cathode is
marked by a line painted on
the body. Diodes are labelled
with their code in small print,
you may need a magnifying glass to read this on small
signal diodes! Small signal diodes can be damaged by heat when
soldering, but the risk is small
unless you are using a germanium diode (codes beginning OA...) in which case
you should use a heat sink
clipped to the lead between
the joint and the diode body. A
standard crocodile clip can be
used as a heat sink. Rectifier diodes are quite robust and no special
precautions are needed for
soldering them. Testing diodes You can use a multimeter or a simple tester (battery, resistor and LED) to check that a diode
conducts in one direction but
not the other. A lamp may be
used to test a rectifier diode , but do NOT use a lamp to test a signal diode because the large current passed by the lamp will
destroy the diode! Signal diodes (small
current) Signal diodes are used to
process information (electrical
signals) in circuits, so they are
only required to pass small
currents of up to 100mA. General purpose signal diodes
such as the 1N4148 are made
from silicon and have a
forward voltage drop of 0.7V. Germanium diodes such as the OA90 have a lower forward
voltage drop of 0.2V and this
makes them suitable to use in
radio circuits as detectors
which extract the audio signal
from the weak radio signal. For general use, where the size
of the forward voltage drop is
less important, silicon diodes
are better because they are
less easily damaged by heat
when soldering, they have a lower resistance when
conducting, and they have very
low leakage currents when a
reverse voltage is applied. Protection diodes for relays Signal diodes are also used to
protect transistors and ICs from
the brief high voltage produced
when a relay coil is switched
off. The diagram shows how a
protection diode is connected 'backwards' across the relay
coil. Current flowing through a relay
coil creates a magnetic field
which collapses suddenly when
the current is switched off. The
sudden collapse of the
magnetic field induces a brief high voltage across the relay
coil which is very likely to
damage transistors and ICs.
The protection diode allows the
induced voltage to drive a brief
current through the coil (and diode) so the magnetic field
dies away quickly rather than
instantly. This prevents the
induced voltage becoming high
enough to cause damage to
transistors and ICs. Rectifier diodes (large
current) Rectifier diodes are used in
power supplies to convert
alternating current (AC) to
direct current (DC), a process
called rectification. They are
also used elsewhere in circuits where a large current must
pass through the diode. All rectifier diodes are made
from silicon and therefore have
a forward voltage drop of 0.7V.
The table shows maximum
current and maximum reverse
voltage for some popular rectifier diodes. The 1N4001 is
suitable for most low voltage
circuits with a current of less
than 1A.
L.E.D - light emiting diode
Function LEDs emit light when an
electric current passes through
them. Connecting and
soldering LEDs must be connected the
correct way round, the diagram
may be labelled a or + for anode and k or - for cathode (yes, it really is k, not c, for
cathode!). The cathode is the
short lead and there may be a
slight flat on the body of round
LEDs. If you can see inside the
LED the cathode is the larger electrode (but this is not an
official identification method). LEDs can be damaged by heat
when soldering, but the risk is
small unless you are very slow.
No special precautions are
needed for soldering most
LEDs. Testing an LED Never connect an LED directly
to a battery or power supply! It will be destroyed almost
instantly because too much
current will pass through and
burn it out. LEDs must have a resistor in
series to limit the current to a
safe value, for quick testing
purposes a 1k resistor is suitable for most LEDs if your
supply voltage is 12V or less. Remember to connect the LED
the correct way round!
Zener diode
Zener diodes are used to
maintain a fixed voltage. They
are designed to 'breakdown' in
a reliable and non-destructive
way so that they can be used in reverse to maintain a fixed voltage across their terminals.
The diagram shows how they
are connected, with a resistor
in series to limit the current. Zener diodes can be
distinguished from ordinary
diodes by their code and
breakdown voltage which are
printed on them. Zener diode
codes begin BZX... or BZY... Their breakdown voltage is
printed with V in place of a
decimal point, so 4V7 means
4.7V for example. Zener diodes are rated by their
breakdown voltage and
maximum power: The minimum voltage available
is 2.4V. Power ratings of 400mW and
1.3W are common.
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TYPES OF CAPACITOR
(non polarized capacitor)
1. Mylar
2. Ceramic
3. Tantalum
4. Paper
(polarized capacitor) meaning may positive at negative sya. Di pwedeng pagpalit palitin ng koneksyon
5. Electrolytic
Variable Capacitor
Eto
yung pinipihit natin sa radyo, kung anong radio station ang gusto mo
mapakinggan, kung love radio o campus ka makikinig, tuner sya kumbaga.
