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Chapter 2 Resistors
2.1 Symbols.
Figure 2.1 resistor symbol
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2.2 Resistor values.
Common resistors comes in values from some milli-ohms, to several Mega-ohms.
The Maximum voltage is depending on the power and the resistor value in Ohms .
(P=U .I)
Common values here are 1/8 watt to 50 Watt resistors
Figure 2.2 Prefix values for values (also for coils and capacitors)
Most axial resistors use a pattern of colored stripes to indicate resistance, which also indicate
tolerance, and may also be extended to show temperature coefficient and reliability class.
Cases are usually tan, brown, blue, or green, though other colors are occasionally found such
as dark red or dark gray. The power rating is not usually marked and is deduced from the size.
The color bands of the carbon resistors can be four, five or, six bands. The first two bands
represent first two digits to measure their value in ohms. The third band of a four-banded
resistor represents multiplier and the fourth band as tolerance. For five and six color-banded
resistors, the third band is a third digit, fourth band multiplier and fifth is tolerance. The sixth
band represents temperature co-efficient in a six-banded resistor.
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Figure 2.3 Color code
Figure 2.3 E12 series, 12 preferred values.
There are also E12, E24, E48, E96 and E192 series
Surface mounted resistors are marked numerically, if they are big enough to permit marking;
more-recent small sizes are impractical to mark.
Surface mounted resistors are printed with numerical values in a code related to that used on
axial resistors. Standard-tolerance surface-mount technology (SMT) are marked with a threedigit code, in which the first two digits are the first two significant digits of the value and the
third digit is the power of ten (the number of zeroes). For example:
334 = 33 × 104 ohms = 330 kilohms
222 = 22 × 102 ohms = 2.2 kilohms
473 = 47 × 103 ohms = 47 kilohms
105 = 10 × 105 ohms = 1 megohm
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Resistances less than 100 ohms are written: 100, 220, 470. The final zero represents ten to the
power zero, which is 1. For example:
100 = 10 × 100 ohm = 10 ohms
220 = 22 × 100 ohm = 22 ohms
Sometimes these values are marked as 10 or 22 to prevent a mistake.
Resistances less than 10 ohms have 'R' to indicate the position of the decimal point (radix
point). For example:
4R7 = 4.7 ohms
R300 = 0.30 ohms
0R22 = 0.22 ohms
0R01 = 0.01 ohms
Precision resistors are marked with a four-digit code, in which the first three digits are the
significant figures and the fourth is the power of ten. For example:
1001 = 100 × 101 ohms = 1.00 kilohm
4992 = 499 × 102 ohms = 49.9 kilohm
1000 = 100 × 100 ohm = 100 ohms
000 and 0000 sometimes appear as values on surface-mount zero ohms, since these have
(approximately) zero resistance.
More recent surface-mount resistors are too small, physically, to permit practical markings to
be applied.
Figure 2.4 SMD resistors values.
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2.3 Packages.
Fig 2.5 typical axial through hole resistors
Fig 2.6 High power (50 Watt) resistor
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Figure 2.7 SMD resistor and capacitor sizes (source : www.interfacebus.com)
Figure 2.8 Typical precision resistor networks. (source:Analogue Devices)
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Figure 2.9 Resistor network with symbol.
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Variable resistors
Figure 2.10 variable resistors: some packages
Linear taper potentiometer
A linear taper potentiometer (linear describes the electrical
characteristic of the device, not the geometry of the resistive
element) has a resistive element of constant cross-section,
resulting in a device where the resistance between the contact
(wiper) and one end terminal is proportional to the distance
between them. Linear taper potentiometers are used when the
division ratio of the potentiometer must be proportional to the
angle of shaft rotation (or slider position), for example,
controls used for adjusting the centering of the display on an analog cathode-ray oscilloscope.
Precision potentiometers have an accurate relationship between resistance and slider position.
Logarithmic potentiometer
A logarithmic taper potentiometer has a resistive element that either 'tapers' in from one end
to the other, or is made from a material whose resistivity varies from one end to the other.
This results in a device where output voltage is a logarithmic function of the slider position.[3]
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Most (cheaper) "log" potentiometers are not accurately logarithmic, but use two regions of
different resistance (but constant resistivity) to approximate a logarithmic law. The two
resistive tracks overlap at approximately 50% of the potentiometer rotation; this gives a
stepwise logarithmic taper. A logarithmic potentiometer can also be simulated (not very
accurately) with a linear one and an external resistor. True logarithmic potentiometers are
significantly more expensive.
Logarithmic taper potentiometers are often used in connection with audio amplifiers as human
perception of audio volume is logarithmic.
2.4 Maximum Power
Resistors are rated by the value of their resistance and the Electrical Power
in Watts, (W) that they can safely dissipate based mainly upon their size. Every resistor has a
maximum power rating which is determined by its physical size as generally, the greater its
surface area the more power it can dissipate safely into the ambient air or into a heatsink.
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Chapter 3 Capacitors
3.1 Capacitor symbols
Figure 3.1 Capacitor values
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3.2 Capacitor values
Figure 3.2 construction Capacitor
The value of a capacitor , depends on the Dielectric the distance of the plats an
the surface of the plates. The unit is Farad.(F)
Typical values comes from pico farad to Fahrads.
For higher values (0.1 uF to 10.000 uF we use electrolytic capacitors) . The have
a polarity, that should not be connected wrong. There is a change of explosion.
The super capacitors or Gold Caps has values up to 10.000 F. they are
expensive.
Breakdown voltage
Above a particular electric field, known as the dielectric strength Eds, the
dielectric in a capacitor becomes conductive. The voltage at which this occurs is
called the breakdown voltage of the device, and is given by the product of the
dielectric strength and the separation between the conductors the maximum
energy that can be stored safely in a capacitor is limited by the breakdown
voltage. Special for the electrolytic capacitors and the Tantal capacitor we must
choose the capacitor , not only on their value in Farad, but also on the maximum
Voltage.
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3.3 Capacitor Packages
Figure 3.3 typical Capacitors
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Figure 3.4 Tantalic capacitors.
Figure 3.5 Gold Cap. (values to 10.000 F. )
Figure 3.6 High power capacitor
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Chapter 4 Electromagnetic Coils Inductor
An inductor, also called a coil or reactor, is a passive two terminal electrical which resists changes in
electrical current passing through it. It consists of a conductor such as a wire, usually wound into a
coil. When a current flows through it, energy is stored temporarily in a magnatic field in the coil.
4.1 Inductor Symbols
Figure 4.1 Inductor symbol
4.2 Values
An inductor is characterized by its inductance, the ratio of the voltage to the rate of change of
current, which has units of henries (H). Inductors have values that typically range from 1 µH (10−6H)
to 1 H.
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4.3 Packages
Figure 4.2 Some typical inductors
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Figure 4.3 Large 50MVAR three-phase iron-core loading inductor at German utility
substation
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Sources:
Wikipedia
http://www.resistorguide.com/resistor-sizes-and-packages/
http://www.talkingelectronics.com/projects/Testing%20Electronic%20Components/TestingC
omponents.html)
And look at :http://www.youtube.com/watch?v=Xwp5KT3E558
All websites form 8september 2014
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