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Description |
Symbol |
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Transistors: Pin outs
left and Symbol on the right, they are used in many circuits as
amplifiers, switches, and power RF and Audio stages.
They come in two types
NPN and PNP, shown below the structure of an NPN
transistor.
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- NPN
- PNP
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The transformer has many
uses there are Mains transformer designed to reduce the mains
voltage down from 220v to just about any voltage needed usually
24/12/9/6/5 volts.
There are also audio
transformers and specialist transformers they all use the same type
symbol right. |
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Meters such as the one
shown left are used for many forms of measurement, this can range
from Voltage and Current to to Ohms and Signal strength in receivers
and transmitters.
They are one of the
earliest forms of electronic measuring instrument, Symbol
right. |
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The Fuse, a very
important part of any electrical or electronic circuit, it protect
any circuit from damage by over current or protects us from electric
shock in the event of a short circuit.
Fuses come in many forms
glass, and spade types and also thermal fuses for protecting
overheating circuits. |
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A Crystal or Resonator,
used in oscillator circuits for many application, can be the main
component of the first RF stage in a transmitter oscillator,
only works on the frequency it is cut for, the case will be stamped
with its operating frequency. |
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A Relay:- used for
switching of larger currents, they are used in many circuits the
principle is that a small amount of current can be used to open or
close the relays contacts, the contacts can be used to switch
anything on or off and the current is only limited by the
size of the contact area.
A relay using a coil of
say 12v at 200mA can be used to switch a mains 220v supply of up to
13A depending on the relay's contacts.
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Variable and trimmer
capacitors are the same in design it is only the way they are used
in a circuit that determines the name and the symbol
used.
On the right you can see
the two symbols top is a variable capacitor and underneath is a
trimmer capacitor, the trimmer capacitor is intended for initial
setup and to be left at that value while a variable capacitor is
intended for more use. |
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Same as in the capacitors
above these are preset and variable resistors.
On the right you can see
the two symbols top is a variable resistor and underneath
is a trimmer resistor, the trimmer again is intended for
initial setup and to be left at that value while a
variable resistor is intended for more use. |
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The Diode is a
semiconductor its wire terminals are called the anode and
cathode, current will only flow in one direction from the anode to
the cathode.
It is used as a detector
a rectifier and in any circuit where we need to stop current flowing
in one direction but not in the other.
The Diode bridge
rectifier circuit shown lower right shows how we can use 4 diodes to
make a Bridge rectifier, the coloured arrows show the current flow
in the bridge.
There is one other type
of diode this is called a Zener diode symbol right bottom, these can
look the same in encapsulation but are voltage sensitive and are
used in low current voltage regulation they come in voltages 3.3, 5,
6, 9, and 12v. |
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This is the symbol for
any antenna system, used in all radio receivers both amateur and
domestic radio's and television receivers. |
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This is the symbol used
for earth, same as in antenna's this is the general symbol used for
earth in radio, television and electronic circuits.
Also used in general
electrical systems such as house wiring, and electric supply
services. |
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Battery or Cell, the
symbol on the right is the symbol used in most circuits for the
Battery, it is a standard symbol, and no matter what type of battery
used this is the symbol. |
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