Transcript Electronic Components

Electronic Components
BADI Year 2
John Errington MSc
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Passive components
Resistors
Capacitors
Inductors
2
* Active components *
Diodes & rectifiers
Transistors
Thyristors
3
Resistor colour code
4
Capacitor codes
5
Diodes
+
I
A diode is a device that only lets
current flow one way.
Signal diodes look like a glass
bead on a thin wire.
Single rectifier diodes are often
packaged similarly, but in a black
plastic envelope with thick wire
leads.
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Rectifiers
• Rectifiers are diodes
that are specially made
to handle large
currents (>1A)
• They are often
packaged in a ‘bridge’
as this allows more
effective rectification
• Connections and
values are shown on
the package
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Transistors
Ic
Ib
• Transistors allow a
small current (Ib)
to control a larger
current (Ic)
• They are used as
amplifiers and
switches
• The gain (Ic/Ib) is
usually between
10 and 1000
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Thyristors (SCR’s)
• Used for controlling power in ac circuits
• Also used for switching dc currents: the Thyristor acts as a
switch. It is turned on by a current through the gate circuit.
It can only be turned off by removing the anode current.
Main current flow
Anode
Cathode
Gate
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Thyristor 1
• No supply to anode
• No gate current
• Lamp off
+
R
-
10
Thyristor 2
• Supply to anode
• No gate current
• Lamp off
+
R
-
11
Thyristor 3
• Supply to anode
• Gate current
• Lamp on
+
R
-
12
Thyristor 3
• Supply to anode
• Gate current removed
• Lamp stays on
+
R
-
13
Thyristor 4
• No supply to anode
• No gate current
• Lamp off
+
R
-
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Links
http://www.elexp.com/tips.htm
http://www.ee.ualberta.ca/html/cookbook.html
electronic cookbook archive
http://www.electro-tech-online.com/
technology projects forum etc
http://www.irf.com/technical-info/guide/circuit.html
http://electronics.howstuffworks.com/
http://www.clear-skies.org/
grants for renewable energy installations
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