Transcript Transistors and ICs

Transistors and ICs
The SCR
• SCR = SILICON
CONTROLLED RECTIFIER
• In the family of
semiconductors that
includes transistors and
diodes.
• Controls current in one
direction
• Not all SCRs use the casing
shown, but this is typical of
most of the high-power
units.
From
http://www.tpub.com/neets/book7/26c.htm
The electrical engineering training series
anode
220 Ohms
1K Ohms
9 volts
cathode
+
gate
-
Beveled Edge front
Gate
Anode
• Note: the cathode side is
towards the negative
side of the battery
• A SCR is very sensitive
to too much electrical
energy, we use a 1000
ohm resistor to protect
the SCR from burning
out.
• Which part of the SCR
needs very little current?
• The gate
• Which side is the
beveled edge?
• The gate
Similar to a basic light switch,
transistors have two operating
positions, on and off.
•The transistor is a solid state
semiconductor device
•can be used for amplification,
switching, voltage stabilization, signal
modulation and many other functions.
• It acts as a variable valve which,
based on its input voltage, controls the
current drawn by it from a connected
voltage supply.
The 555 timer is an extremely versatile
integrated circuit which can be used to
build lots of different circuits.
Integrated circuits are used for a
variety of devices, including :
•microprocessors,
•audio and video equipment,
• automobiles and more
Integrated circuits are often classified by the number of
transistors and other electronic components they contain:
SSI (small-scale integration): Up to 100 electronic components
per chip
MSI (medium-scale integration): From 100 to 3,000 electronic
components per chip
LSI (large-scale integration): From 3,000 to 100,000 electronic
components per chip
VLSI (very large-scale integration): From 100,000 to 1,000,000
electronic components per chip
ULSI (ultra large-scale integration): More than 1 million
electronic components per chip