WIRELESS LOAD
CONTROLLER BY GSM
GURU TEGH BAHADUR INSTITUTE OF
TECHNOLOGY
SUBMITTED BY
ANANT KUMAR SHARMA
0901324906, EEE 7TH SEMESTER
SHEKHAR SINGH
0971324906, EEE 7TH SEMESTER
AIM:To design & develop the wireless controller load by the GSM.
ABSTRACT:GSM contoller is a low cost solution to Remote Control and Monitoring via your
mobile phone. It has 2 relay outputs and 4 contact closure inputs. Outputs can be
used to control lighting, central heating boiler, pumps etc and the inputs can be
connected to thermostats, security sensors and flood detectors. An optional
wireless interface allows communicate with an expanding range of security and
fire sensors, heating thermostats for temperature control and panic switches.
Description:
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GSM Control Unit using SMS text messaging
2 x mains rated relay outputs for switching for example lights, pumps,
central heating
4 x contact closure inputs from example PIR detectors, flood detectors,
security alarm systems etc
Can switch on/off outputs from simple SMS text message
Can send an SMS message when a input changes state
Uses standard mobile phone SIM card, including pre-paid
Easy to use and configure via SMS, the internet or optional USB lead
Optional battery back-up for operation even during mains power failure
Optional wireless sensor interface for use with;
o Wireless thermostat for heating control
o Wireless Fire and Smoke detectors
o Wireless PIR and Glass break Security sensor
o Wireless remote switch output unit
o Wireless Panic or Wrist button for th infirm
Add SMS alerting to your security alarm
Remote control and monitoring of your 2nd or holiday home
Central heating control via your mobile phone
24 hour property flood monitoring
OPERATION:-
Switching Outputs from your Phone:-
Two output terminals (X or Y) can be used as:
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An SMS-controlled switch. SMS texts for switching particular terminals
on/off are configurable (e.g. "light on", "light off" and "sunblind close",
"sunblind open"). Any such instruction can be automatically echoed by
David sending you an SMS report.
A time-switch which can be activated remotely via a mobile phone. (the
switch-on period is configurable from 1 second to 10 hours).
A relay with dialling-in remote control. Up to 50 tel. numbers can be
authorized for each relay. Because calls are not answered dialling-in control
within GSM is free of charge. (David only checks the caller’s number and –
if the number is authorized – responds with relay activation.) This can be
used for parking access control, door lock control, switching lights etc.
Each authorized number can have a limit to the number of calls. For example,
when the customer is only allowed to open the parking lot entrance for 30 times at
most, any further access is denied to him/her. The customer can then be reauthorized for entrance control via SMS by the administrator.
Reporting Inputs to your phone:-
Four input terminals (A to D) can have their switching on/off reported by SMS
(e.g. "freezer mains dropout" or "freezer mains recovered")
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SMS reports can contain up to 30 characters.
Each input can have up to 8 tel. numbers programmed for where reports are
sent to.
SMS reports can be emphasized by subsequent calls.
David’s current status (input/output terminal states) can be interrogated
remotely via SMS instructions.
David can perform periodical calls every 24 hours allowing you to monitor
its functioning.
If you use a prepaid SIM card, David can send you a warning SMS
whenever a critically low credit balance is detected on periodic
interrogation.
POWER SUPPLY
In alternating current the electron flow is alternate, i.e. the electron flow
increases to maximum in one direction, decreases back to zero. It then increases in
the other direction and then decreases to zero again. Direct current flows in one
direction only. Rectifier converts alternating current to flow in one direction only.
When the anode of the diode is positive with respect to its cathode, it is forward
biased, allowing current to flow. But when its anode is negative with respect to the
cathode, it is reverse biased and does not allow current to flow. This unidirectional
property of the diode is useful for rectification. A single diode arranged back-toback might allow the electrons to flow during positive half cycles only and
suppress the negative half cycles. Double diodes arranged back-to-back might act
as full wave rectifiers as they may allow the electron flow during both positive and
negative half cycles. Four diodes can be arranged to make a full wave bridge
rectifier. Different types of filter circuits are used to smooth out the pulsations in
amplitude of the output voltage from a rectifier. The property of capacitor to
oppose any change in the voltage applied across them by storing energy in the
electric field of the capacitor and of inductors to oppose any change in the current
flowing through them by storing energy in the magnetic field of coil may be
utilized. To remove pulsation of the direct current obtained from the rectifier,
different types of combination of capacitor, inductors and resistors may be also be
used to increase to action of filtering.
THEORY
USE OF DIODES IN RECTIFIERS:
Electric energy is available in homes and industries in India, in the form of
alternating voltage. The supply has a voltage of 220V (rms) at a frequency of 50
Hz. In the USA, it is 110V at 60 Hz. For the operation of most of the devices in
electronic equipment, a dc voltage is needed. For instance, a transistor radio
requires a dc supply for its operation. Usually, this supply is provided by dry cells.
But sometime we use a battery eliminator in place of dry cells. The battery
eliminator converts the ac voltage into dc voltage and thus eliminates the need for
dry cells. Nowadays, almost all-electronic equipment includes a circuit that
converts ac voltage of mains supply into dc voltage. This part of the equipment is
called Power Supply. In general, at the input of the power supply, there is a power
transformer. It is followed by a diode circuit called Rectifier. The output of the
rectifier goes to a smoothing filter, and then to a voltage regulator circuit. The
rectifier circuit is the heart of a power supply.
RECTIFICATION
Rectification is a process of rendering an alternating current or voltage into a
unidirectional one. The component used for rectification is called ‘Rectifier’. A
rectifier permits current to flow only during the positive half cycles of the applied
AC voltage by eliminating the negative half cycles or alternations of the applied
AC voltage. Thus pulsating DC is obtained. To obtain smooth DC power,
additional filter circuits are required.
A diode can be used as rectifier. There are various types of diodes. But,
semiconductor diodes are very popularly used as rectifiers. A semiconductor diode
is a solid-state device consisting of two elements is being an electron emitter or
cathode, the other an electron collector or anode. Since electrons in a
semiconductor diode can flow in one direction only-from emitter to collector- the
diode provides the unilateral conduction necessary for rectification. Out of the
semiconductor diodes, copper oxide and selenium rectifier are also commonly
used.
FULL WAVE RECTIFIER
It is possible to rectify both alternations of the input voltage by using two
diodes in the circuit arrangement. Assume 6.3 V rms (18 V p-p) is applied to the
circuit. Assume further that two equal-valued series-connected resistors R are
placed in parallel with the ac source. The 18 V p-p appears across the two resistors
connected between points AC and CB, and point C is the electrical midpoint
between A and B. Hence 9 V p-p appears across each resistor. At any moment
during a cycle of vin, if point A is positive relative to C, point B is negative
relative to C. When A is negative to C, point B is positive relative to C. The
effective voltage in proper time phase which each diode "sees" is in Fig. The
voltage applied to the anode of each diode is equal but opposite in polarity at any
given instant.
When A is positive relative to C, the anode of D1 is positive with respect to
its cathode. Hence D1 will conduct but D2 will not. During the second alternation,
B is positive relative to C. The anode of D2 is therefore positive with respect to its
cathode, and D2 conducts while D1 is cut off.
There is conduction then by either D1 or D2 during the entire input-voltage
cycle.
Since the two diodes have a common-cathode load resistor RL, the output
voltage across RL will result from the alternate conduction of D1 and D2. The
output waveform vout across RL, therefore has no gaps as in the case of the halfwave rectifier.
The output of a full-wave rectifier is also pulsating direct current. In the
diagram, the two equal resistors R across the input voltage are necessary to provide
a voltage midpoint C for circuit connection and zero reference. Note that the load
resistor RL is connected from the cathodes to this center reference point C.
An interesting fact about the output waveform vout is that its peak amplitude
is not 9 V as in the case of the half-wave rectifier using the same power source, but
is less than 4½ V. The reason, of course, is that the peak positive voltage of A
relative to C is 4½ V, not 9 V, and part of the 4½ V is lost across R.
Though the full wave rectifier fills in the conduction gaps, it delivers less
than half the peak output voltage that results from half-wave rectification.
Filtration
The rectifier circuits we have discussed above deliver an output voltage that
always has the same polarity: but however, this output is not suitable as DC power
supply for solid-state circuits. This is due to the pulsation or ripples of the output
voltage. This should be removed out before the output voltage can be supplied to
any circuit. This smoothing is done by incorporating filter networks. The filter
network consists of inductors and capacitors. The inductors or choke coils are
generally connected in series with the rectifier output and the load. The inductors
oppose any change in the magnitude of a current flowing through them by storing
up energy in a magnetic field. An inductor offers very low resistance for DC
whereas; it offers very high resistance to AC. Thus, a series connected choke coil
in a rectifier circuit helps to reduce the pulsations or ripples to a great extent in the
output voltage. The fitter capacitors are usually connected in parallel with the
rectifier output and the load. As, AC can pass through a capacitor but DC cannot,
the ripples are thus limited and the output becomes smoothed. When the voltage
across its plates tends to rise, it stores up energy back into voltage and current.
Thus, the fluctuations in the output voltage are reduced considerable. Filter
network circuits may be of two types in general:
CAPACITOR INPUT FILTER
If a capacitor is placed before the inductors of a choke-input filter network,
the filter is called capacitor input filter. The D.C. along with AC ripples from the
rectifier circuit starts charging the capacitor C. to about peak value. The AC ripples
are then diminished slightly. Now the capacitor C, discharges through the inductor
or choke coil, which opposes the AC ripples, except the DC. The second capacitor
C by passes the further AC ripples. A small ripple is still present in the output of
DC, which may be reduced by adding additional filter network in series.
PRINTED CIRCUIT BOARD
Printed circuit boards are used for housing components to make a circuit, for
comactness, simplicity of servicing and ease of interconnection. Single sided,
double sided and double sided with plated-through-hold (PYH) types of p.c boards
are common today.
Boards are of two types of material (1) phenolic paper based material (2)
Glass epoxy material. Both materials are available as laminate sheets with copper
cladding.
Printed circuit boards have a copper cladding on one or both sides. In both
boards, pasting thin copper foil on the board during curing does this. Boards are
prepared in sizes of 1 to 5 metre wide and upto 2 metres long. The thickness of the
boards is 1.42 to 1.8mm. The copper on the boards is about 0.2 thick and weighs
and ounce per square foot.
TRANSFORMER
PRINCIPLE OF THE TRANSFORMER:-
Two coils are wound over a Core such that they are magnetically coupled.
The two coils are known as the primary and secondary windings.
In a Transformer, an iron core is used. The coupling between the coils is
source of making a path for the magnetic flux to link both the coils. A core as in
fig.2 is used and the coils are wound on the limbs of the core. Because of high
permeability of iron, the flux path for the flux is only in the iron and hence the flux
links both windings. Hence there is very little ‘leakage flux’. This term leakage
flux denotes the part of the flux, which does not link both the coils, i.e., when
coupling is not perfect. In the high frequency transformers, ferrite core is used. The
transformers may be step-up, step-down, frequency matching, sound output,
amplifier driver etc. The basic principles of all the transformers are same.
TRANSISTOR
The name is transistor derived from ‘transfer resistors’ indicating a solid
state Semiconductor device. In addition to conductor and insulators, there is a third
class of material that exhibits proportion of both. Under some conditions, it acts as
an insulator, and under other conditions it’s a conductor. This phenomenon is
called Semi-conducting and allows a variable control over electron flow. So, the
transistor is semi conductor device used in electronics for amplitude. Transistor has
three terminals, one is the collector, one is the base and other is the emitter, (each
lead must be connected in the circuit correctly and only then the transistor will
function). Electrons are emitted via one terminal and collected on another terminal,
while the third terminal acts as a control element. Each transistor has a number
marked on its body. Every number has its own specifications.
There are mainly two types of transistor (i) NPN & (ii) PNP
NPN Transistors:
When a positive voltage is applied to the base, the transistor begins to
conduct by allowing current to flow through the collector to emitter circuit. The
relatively small current flowing through the base circuit causes a much greater
current to pass through the emitter / collector circuit. The phenomenon is called
current gain and it is measure in beta.
PNP Transistor:
It also does exactly same thing as above except that it has a negative voltage
on its collector and a positive voltage on its emitter.
Transistor is a combination of semi-conductor elements allowing a
controlled current flow. Germanium and Silicon is the two semi-conductor
elements used for making it. There are two types of transistors such as POINT
CONTACT and JUNCTION TRANSISTORS. Point contact construction is
defective so is now out of use. Junction triode transistors are in many respects
analogous to triode electron tube.
A junction transistor can function as an amplifier or oscillator as can a triode
tube, but has the additional advantage of long life, small size, ruggedness and
absence of cathode heating power.
Junction transistors are of two types which can be obtained while
manufacturing.
The two types are: -
1)
PNP TYPE: This is formed by joining a layer of P type of
to an N-P Junction
P
N
germanium
P
2)
NPN TYPE:This is formed by joining a layer of N type germanium to a PN Junction.
N
P
N
Both types are shown in figure, with their symbols for representation. The
centre section is called the base, one of the outside sections-the emitter and the
other outside section-the collector. The direction of the arrowhead gives the
direction of the conventional current with the forward bias on the emitter. The
conventional flow is opposite in direction to the electron flow.
OPERATION OF PNP TRANSISTOR:-
A PNP transistor is made by sand witching two PN germanium or silicon
diodes, placed back to back. The centre of N-type portion is extremely thin in
comparison to P region. The P region of the left is connected to the positive
terminal and N-region to the negative terminal i.e. PN is biased in the forward
direction while P region of right is biased negatively i.e. in the reverse direction as
shown in Fig. The P region in the forward biased circuit is called the emitter and P
region on the right, biased negatively is called collector. The centre is called base.
The majority carriers (holes) of P region (known as emitter) move to N
region as they are repelled by the positive terminal of battery while the electrons of
N region are attracted by the positive terminal. The holes overcome the barrier and
cross the emitter junction into N region. As the width of base region is extremely
thin, two to five percent of holes recombine with the free electrons of N-region
which result in a small base current while the remaining holes (95% to 98%) reach the
collector junction. The collector is biased negatively and the negative collector
voltage aids in sweeping the hole into collector region.
As the P region at the right is biased negatively, a very small current should
flow but the following facts are observed:-
1)
A substantial current flows through it when the emitter junction is biased in a
forward direction.
2)
The current flowing across the collector is slightly less than that of the
emitter, and
3)
The collector current is a function of emitter current i.e. with the decrease or
increase in the emitter current a corresponding change in the collector current
is observed.
The facts can be explained as follows:-
1. As already discussed that 2 to 5% of the holes are lost in recombination with the electron n base
region, which result in a
small base current and hence the collector current is slightly less than the
emitter current.
2.
The collector current increases as the holes reaching the collector junction are
attracted by negative potential applied to the collector.
3.
When the emitter current increases, most holes are injected into the
base
region, which is attracted by the negative potential of the collector and hence
results in increasing the collector current. In this way emitter is analogous to
the control of plate current by small grid voltage in a vacuum triode.
Hence we can say that when the emitter is forward biased and collector is
negatively biased, a substantial current flows in both the circuits. Since a small emitter
voltage of about 0.1 to 0.5 volts permits the flow of an appreciable emitter current the
input power is very small. The collector voltage can be as high as 45 volts.
Resistors
The resistor's function is to reduce the flow of electric current.
This symbol
is used to indicate a resistor in a circuit diagram, known as a
schematic.
Resistance value is designated in units called the "Ohm." A 1000 Ohm resistor is
typically shown as 1K-Ohm ( kilo Ohm ), and 1000 K-Ohms is written as 1M-Ohm (
megohm ).
There are two classes of resistors; fixed resistors and the variable resistors. They are
also classified according to the material from which they are made. The typical
resistor is made of either carbon film or metal film. There are other types as well, but
these are the most common.
The resistance value of the resistor is not the only thing to consider when selecting a
resistor for use in a circuit. The "tolerance" and the electric power ratings of the
resistor are also important.
The tolerance of a resistor denotes how close it is to the actual rated resistance value.
For example, a ±5% tolerance would indicate a resistor that is within ±5% of the
specified resistance value.
The power rating indicates how much power the resistor can safely tolerate. Just like
you wouldn't use a 6 volt flashlight lamp to replace a burned out light in your house,
you wouldn't use a 1/8 watt resistor when you should be using a 1/2 watt resistor.
The maximum rated power of the resistor is specified in Watts.
Power is calculated using the square of the current ( I2 ) x the resistance value ( R ) of
the resistor. If the maximum rating of the resistor is exceeded, it will become
extremely hot, and even burn.
Resistors in electronic circuits are typicaly rated 1/8W, 1/4W, and 1/2W. 1/8W is
almost always used in signal circuit applications.
When powering a light emitting diode, a comparatively large current flows through
the resistor, so you need to consider the power rating of the resistor you choose.
Rating electric power
For example, to power a 5V circuit using a 12V supply, a three-terminal
voltage regulator is usually used.
However, if you try to drop the voltage from 12V to 5V using only a resistor,
then you need to calculate the power rating of the resistor as well as the
resistance value.
At this time, the current consumed by the 5V circuit needs to be known.
Here are a few ways to find out how much current the circuit demands.
Assemble the circuit and measure the actual current used with a multi-meter.
Check the component's current use against a standard table.
Assume the current consumed is 100 mA (milliamps) in the following example.
7V must be dropped with the resistor. The resistance value of the resistor
becomes 7V / 0.1A = 70(ohm). The consumption of electric power for this
resistor becomes 0.1A x 0.1A x 70 ohm = 0.7W.
Generally, it's safe to choose a resistor which has a power rating of about twice
the power consumption needed.
Resistance value
As for the standard resistance value, the values used can be divided like a
logarithm. ( See the logarithm table)
For example, in the case of E3, The values [1], [2.2], [4.7] and [10] are used.
They divide 10 into three, like a logarithm.
In the case of E6 : [1], [1.5], [2.2], [3.3], [4.7], [6.8], [10].
In the case of E12 : [1], [1.2], [1.5], [1.8], [2.2], [2.7], [3.3], [3.9], [4.7], [5.6],
[6.8], [8.2], [10].
It is because of this that the resistance value is seen at a glance to be a discrete
value.
The resistance value is displayed using the color code ( the colored bars/the
colored stripes ), because the average resistor is too small to have the value
printed on it with numbers.
You had better learn the color code, because almost all resistors of 1/2W or less
use the color-code to display the resistance value.
Fixed Resistors
A fixed resistor is one in which the value of its resistance cannot change.
Carbon film resistors
This is the most general purpose, cheap resistor. Usually the tolerance of the
resistance value is ±5%. Power ratings of 1/8W, 1/4W and 1/2W are frequently
used.
Carbon film resistors have a disadvantage; they tend to be electrically noisy.
Metal film resistors are recommended for use in analog circuits. However, I
have never experienced any problems with this noise.
The physical size of the different resistors are as follows.
Rough size
From the top of the
photograph
1/8W
1/4W
1/2W
Ratin
Thicknes Lengt
g
s
h
power
(mm) (mm)
(W)
1/8
2
3
1/4
2
6
1/2
3
9
This resistor is called a Single-In-Line(SIL) resistor network. It is made with
many resistors of the same value, all in one package. One side of each resistor
is connected with one side of all the other resistors inside. One example of its
use would be to control the current in a circuit powering many light emitting
diodes (LEDs).
In the photograph on the left, 8 resistors are housed in the package. Each of the
leads on the package is one resistor. The ninth lead on the left side is the
common lead. The face value of the resistance is printed. ( It depends on the
supplier. )
Some resistor networks have a "4S" printed on the top of the resistor network.
The 4S indicates that the package contains 4 independent resistors that are not
wired together inside. The housing has eight leads instead of nine. The internal
wiring of these typical resistor networks has been illustrated below. The size
(black part) of the resistor network which I have is as follows: For the type with
9 leads, the thickness is 1.8 mm, the height 5mm, and the width 23 mm. For the
types with 8 component leads, the thickness is 1.8 mm, the height 5 mm, and
the width 20 mm.
Metal film resistors
Metal film resistors are used when a higher tolerance (more accurate value) is
needed. They are much more accurate in value than carbon film resistors. They
have about ±0.05% tolerance. They have about ±0.05% tolerance. I don't use
any high tolerance resistors in my circuits. Resistors that are about ±1% are
more than sufficient. Ni-Cr (Nichrome) seems to be used for the material of
resistor. The metal film resistor is used for bridge circuits, filter circuits, and
low-noise analog signal circuits.
Rough size
Rating power Thickness Length
(W)
(mm)
(mm)
1/8
2
3
From the top of the photograph
1/8W (tolerance ±1%)
1/4
2
6
1/4W (tolerance ±1%)
1
3.5
12
1W (tolerance ±5%)
2
5
15
2W (tolerance ±5%)
Variable Resistors
There are two general ways in which variable resistors are used. One is the
variable resistor which value is easily changed, like the volume adjustment of
Radio. The other is semi-fixed resistor that is not meant to be adjusted by
anyone but a technician. It is used to adjust the operating condition of the
circuit by the technician. Semi-fixed resistors are used to compensate for the
inaccuracies of the resistors, and to fine-tune a
circuit. The rotation angle of the variable resistor is
usually about 300 degrees. Some variable resistors
must be turned many times to use the whole range of
resistance
they offer.
This allows
for very precise adjustments of their
value. These are called
"Potentiometers" or "Trimmer
Potentiometers."
In the photograph to the left, the variable resistor typically used for volume
controls can be seen on the far right. Its value is very easy to adjust.
The four resistors at the center of the photograph are the semi-fixed type. These
ones are mounted on the printed circuit board.
The two resistors on the left are the trimmer potentiometers.
This symbol
is used to indicate a variable resistor in a circuit diagram.
There are three ways in which a variable resistor's value can change according
to the rotation angle of its axis.
When type "A" rotates clockwise, at first, the resistance value changes slowly
and then in the second half of its axis, it changes very quickly.
The "A" type variable resistor is typically used for the volume control of a
radio, for example. It is well suited to adjust a low sound subtly. It suits the
characteristics of the ear. The ear hears low sound changes well, but isn't as
sensitive to small changes in loud sounds. A larger change is needed as the
volume is increased. These "A" type variable resistors are sometimes called
"audio taper" potentiometers.
As for type "B", the rotation of the axis and the change of the resistance value
are directly related. The rate of change is the same, or linear, throughout the
sweep of the axis. This type suits a resistance value adjustment in a circuit, a
balance circuit and so on.
They are sometimes called "linear taper" potentiometers.
Type "C" changes exactly the opposite way to type "A". In the early stages of
the rotation of the axis, the resistance value changes rapidly, and in the second
half, the change occurs more slowly. This type isn't too much used. It is a
special use.
As for the variable resistor, most are type "A" or type "B".
CDS Elements
Some components can change resistance value by changes in the amount of
light hitting them. One type is the Cadmium Sulfide Photocell. (Cd) The more
light that hits it, the smaller its resistance value becomes.
There are many types of these devices. They vary according to light sensitivity,
size, resistance value etc.
Pictured at the left is a typical CDS photocell. Its diameter is 8 mm, 4 mm high, with a
cylinder form. When bright light is hitting it, the value is about 200 ohms, and when
in the dark, the resistance value is about 2M ohms.
This device is using for the head lamp illumination confirmation device of the car, for
example.
Other Resistors
There is another type of resistor other than the carbon-film type and the metal
film resistors. It is the wirewound resistor.
A wirewound resistor is made of metal resistance wire, and because of this,
they can be manufactured to precise values. Also, high-wattage resistors can be
made by using a thick wire material. Wirewound resistors cannot be used for
high-frequency circuits. Coils are used in high frequency circuits. Since a
wirewound resistor is a wire wrapped around an insulator, it is also a coil, in a
manner of speaking. Using one could change the behavior of the circuit. Still
another type of resistor is the Ceramic resistor. These are wirewound resistors
in a ceramic case, strengthened with a special cement. They have very high
power ratings, from 1 or 2 watts to dozens of watts. These resistors can become
extremely hot when used for high power applications, and this must be taken
into account when designing the circuit. These devices can easily get hot
enough to burn you if you touch one.
The photograph on the left is of wirewound
resistors.
The upper one is 10W and is the length of 45
mm, 13 mm thickness.
The lower one is 50W and is the length of 75
mm, 29 mm thickness.
The upper one is has metal fittings attached.
These devices are insulated with a ceramic
coating.
The photograph on above is a ceramic (or
cement) resistor of 5W and is the height of 9
mm, 9 mm depth, 22 mm width.
Thermistor ( Thermally sensitive resistor )
The resistance value of the thermistor changes according to
temperature.
This part is used as a temperature sensor.
There are mainly three types of thermistor.
NTC(Negative Temperature Coefficient Thermistor)
: With this type, the resistance value decreases continuously
as the temperature rises.
PTC(Positive Temperature Coefficient Thermistor)
: With this type, the resistance value increases suddenly when
the temperature rises above a specific point.
CTR(Critical Temperature Resister Thermistor)
: With this type, the resistance value decreases suddenly when
the temperature rises above a specific point.
The NTC type is used for the temperature control.
The relation between the temperature and the resistance value of the NTC
type can be calculated using the following formula.
R : The resistance value at the temperature T
T : The temperature [K]
R0 : The resistance value at the reference temperature T0
T0 : The reference temperature [K]
B : The coefficient
As the reference temperature, typically, 25°C is used.
The unit with the temperature is the absolute temperature(Value of
which 0 was -273°C) in K(Kelvin).
25°C are the 298 kelvins.
Resistor color code
Example 1
(Brown=1),(Black=0),(Orange=3)
10 x 103 = 10k ohm
Tolerance(Gold) = ±5%
Example 2
(Yellow=4),(Violet=7),(Black=0),(Red
=2)
470 x 102 = 47k ohm
Tolerance(Brown) = ±1%
Color
Valu
e
Multiplie
r
Toleranc
e
(%)
Black
0
0
-
Brown
1
1
±1
Red
2
2
±2
Orang
e
3
3
±0.05
Yellow
4
4
-
Green
5
5
±0.5
Blue
6
6
±0.25
Violet
7
7
±0.1
Gray
8
8
-
White
9
9
-
Gold
-
-1
±5
Silver
-
-2
±10
None
-
-
±20
Diodes
A diode is a semiconductor device which allows
current to flow through it in only one direction.
Although a transistor is also a semiconductor device,
it does not operate the way a diode does. A diode is
specifically made to allow current to flow through it
in only one direction.
Some ways in which the diode can be used are listed here.
A diode can be used as a rectifier that converts AC (Alternating Current) to
DC (Direct Current) for a power supply device.
Diodes can be used to separate the signal from radio frequencies.
Diodes can be used as an on/off switch that controls current.
This symbol
is used to indicate a diode in a circuit diagram.
The meaning of the symbol is (Anode)
(Cathode).
Current flows from the anode side to the cathode side.
Although all diodes operate with the same general principle, there are
different types suited to different applications. For example, the following
devices are best used for the applications noted.
Voltage regulation diode (Zener Diode)
The circuit symbol is
.
It is used to regulate voltage, by taking advantage of the fact that Zener
diodes tend to stabilize at a certain voltage when that voltage is applied in
the opposite direction.
Light emitting diode
The circuit symbol is
.
This type of diode emits light when current flows through it in the
forward direction. (Forward biased.)
Variable capacitance diode
The circuit symbol is
.
The current does not flow when applying the voltage of the opposite
direction to the diode. In this condition, the diode has a capacitance like
the capacitor. It is a very small capacitance. The capacitance of the diode
changes when changing voltage. With the change of this capacitance, the
frequency of the oscillator can be changed.
The graph on the right shows the electrical characteristics of a typical diode.
When a small voltage is applied to the diode in the forward direction, current
flows easily.
Because the diode has a certain amount of resistance, the voltage will drop
slightly as current flows through the diode. A typical diode causes a voltage
drop of about 0.6 - 1V (VF) (In the case of silicon diode, almost 0.6V)
This voltage drop needs to be taken into consideration in a circuit which uses
many diodes in series. Also, the amount
of current passing through the diodes
must be considered.
When voltage is applied in the reverse
direction through a diode, the diode will
have a great resistance to current flow.
Different diodes have different
characteristics when reverse-biased. A
given diode should be selected
depending on how it will be used in the
circuit.
The current that will flow through a diode biased in the reverse direction will
vary from several mA to just µA, which is very small.
The limiting voltages and currents permissible must be considered on a case
by case basis. For example, when using diodes for rectification, part of the
time they will be required to withstand a reverse voltage. If the diodes are not
chosen carefully, they will break down.
Rectification / Switching / Regulation Diode
The stripe stamped on one end of the diode shows indicates the polarity of
the diode.
The stripe shows the cathode side.
The top two devices shown in the picture are diodes used for rectification.
They are made to handle relatively high currents. The device on top can
handle as high as 6A, and the one below it can safely handle up to 1A.
However, it is best used at about 70% of its rating because this current value
is a maximum rating.
The third device from the top (red color) has a part number of 1S1588. This
diode is used for switching, because it can switch on and off at very high
speed. However, the maximum current it can handle is 120 mA. This makes
it well suited to use within digital circuits. The maximum reverse voltage
(reverse bias) this diode can handle is 30V.
The device at the bottom of the picture is a voltage regulation diode with a
rating of 6V. When this type of diode is reverse biased, it will resist changes
in voltage. If the input voltage is increased, the output voltage will not
change. (Or any change will be an insignificant amount.) While the output
voltage does not increase with an increase in input voltage, the output current
will.
This requires some thought for a protection circuit so that too much current
does not flow.
The rated current limit for the device is 30 mA.
Generally, a 3-terminal voltage regulator is used for the stabilization of a
power supply. Therefore, this diode is typically used to protect the circuit
from momentary voltage spikes. 3 terminal regulators use voltage regulation
diodes inside.
Diode bridge
Rectification diodes are used to make DC from AC. It is possible to do only
'half wave rectification' using 1 diode. When 4 diodes are combined, 'full
wave rectification' occurrs.
Devices that combine 4 diodes in
one package are called diode
bridges. They are used for fullwave rectification.
The photograph on the left shows two examples of diode bridges.
The cylindrical device on the right in the photograph has a current limit of
1A. Physically, it is 7 mm high, and 10 mm in diameter.
The flat device on the left has a current limit of 4A. It is has a thickness of 6
mm, is 16 mm in height, and 19 mm in width.
The photograph on the right
shows a large, high-power diode
bridge.
It has a current capacity of 15A.
The peak reverse-bias voltage is
400V.
Diode bridges with large current
capacities like this one, require a
heat sink. Typically, they are
screwed to a piece of metal, or the
chasis of device in which
they are used. The heat
sink allows the device to
radiate excess heat.
As for size, this one is 26
mm wide on each side,
and the height of the
module part is 10 mm.
Light Emitting Diode ( LED )
Light emitting diodes must be choosen according to how they will be used,
because there are various kinds.
The diodes are available in several colors. The most common colors are red
and green, but there are even blue ones.
The device on the far right in the photograph combines a red LED and green
LED in one package. The component lead in the middle is common to both
LEDs. As for the remaing two leads, one side is for the green, the other for
the red LED. When both are turned on simultaneously, it becomes orange.
When an LED is new out of the package, the polarity of the device can be
determined by looking at the leads. The longer lead is the Anode side, and
the short one is the Cathode side.
The polarity of an LED can also be determined using a resistance meter, or
even a 1.5 V battery.
When using a test meter to determine polarity, set the meter to a low
resistance measurement range. Connect the probes of the meter to the LED.
If the polarity is correct, the LED will glow. If the LED does not glow,
switch the meter probes to the opposite leads on
the LED. In either case, the side of the diode
which is connected to the black meter probe
when the LED glows, is the Anode side. Positive
voltage flows out of the black probe when the
meter is set to measure resistance.
It is possible to use an LED to obtain a fixed voltage.
The voltage drop (forward voltage, or VF) of an LED is comparatively stable
at just about 2V.
I explain a circuit in which the voltage was stabilized with an LED in
"Thermometer of bending apparatus-2".
Shottky barrier diode
Diodes are used to rectify alternating current into direct current. However,
rectification will not occur when the frequency of the alternating current is
too high. This is due to what is known as the "reverse recovery
characteristic."
The reverse recovery characteristic can be explained as follows:
IF the opposite voltage is suddenly applied to a forward-biased diode, current
will continue to flow in the forward direction for a brief moment. This time
until the current stops flowing is called the Reverse Recovery Time. The
current is considered to be stopped when it falls to about 10% of the value of
the peak reverse current.
The Shottky barrier diode has a short reverse recovery time, which makes it
ideally suited to use in high frequency rectification.
The shottky barrier diode has the following characteristics.
The voltage drop in the forward direction is low.
The reverse recovery time is short.
However, it has the following disadvantages.
The diode can have relatively high leakage current.
The surge resistance is low.
Because the reverse recovery time is short, this diode is often used for the
switching regulator in a high frequency circuit.
Capacitors
The capacitor's function is to store electricity, or electrical energy.
The capacitor also functions as a filter,
passing alternating current (AC), and
blocking direct current (DC).
This symbol
is used to indicate a
capacitor in a circuit diagram.
The capacitor is constructed with two
electrode plates facing eachother, but
separated by an insulator.
When DC voltage is applied to the capacitor, an electric charge is stored on
each electrode. While the capacitor is charging up, current flows. The current
will stop flowing when the capacitor has fully charged.
When a circuit tester, such as an analog meter set to measure resistance, is
connected to a 10 microfarad (µF) electrolytic capacitor, a current will flow,
but only for a moment. You can confirm that the meter's needle moves off of
zero, but returns to zero right away.
When you connect the meter's probes to the capacitor in reverse, you will note
that current once again flows for a moment. Once again, when the capacitor
has fully charged, the current stops flowing. So the capacitor can be used as a
filter that blocks DC current. (A "DC cut" filter.)
However, in the case of alternating current, the current will be allowed to pass.
Alternating current is similar to repeatedly switching the test meter's probes
back and forth on the capacitor. Current flows every time the probes are
switched.
The value of a capacitor (the capacitance), is designated in units called the
Farad ( F ).
The capacitance of a capacitor is generally very small, so units such as the
microfarad ( 10-6F ), nanofarad ( 10-9F ), and picofarad (10-12F ) are used.
Recently, an new capacitor with very high capacitance has been developed.
The Electric Double Layer capacitor has capacitance designated in Farad units.
These are known as "Super Capacitors."
Sometimes, a three-digit code is used to indicate the value of a capacitor.
There are two ways in which the capacitance can be written. One uses letters
and numbers, the other uses only numbers. In either case, there are only three
characters used. [10n] and [103] denote the same value of capacitance. The
method used differs depending on the capacitor supplier. In the case that the
value is displayed with the three-digit code, the 1st and 2nd digits from the left
show the 1st figure and the 2nd figure, and the 3rd digit is a multiplier which
determines how many zeros are to be added to the capacitance. Picofarad ( pF
) units are written this way.
For example, when the code is [103], it indicates 10 x 103, or 10,000pF = 10
nanofarad( nF ) = 0.01 microfarad( µF ).
If the code happened to be [224], it would be 22 x 104 = or 220,000pF = 220nF
= 0.22µF.
Values under 100pF are displayed with 2 digits only. For example, 47 would
be 47pF.
The capacitor has an insulator( the dielectric ) between 2 sheets of electrodes.
Different kinds of capacitors use different materials for the dielectric.
Breakdown voltage
When using a capacitor, you must pay attention to the maximum voltage
which can be used. This is the "breakdown voltage." The breakdown voltage
depends on the kind of capacitor being used. You must be especially careful
with electrolytic capacitors because the breakdown voltage is comparatively
low. The breakdown voltage of electrolytic capacitors is displayed as Working
Voltage.
The breakdown voltage is the voltage that when exceeded will cause the
dielectric (insulator) inside the capacitor to break down and conduct. When
this happens, the failure can be catastrophic.
I will introduce the different types of capacitors below.
Electrolytic Capacitors (Electrochemical type capacitors)
Aluminum is used for the electrodes by using a thin oxidization membrane.
Large values of capacitance can be obtained in comparison with the size of the
capacitor, because the dielectric used is very thin.
The most important characteristic of electrolytic capacitors is that they have
polarity. They have a positive and a negative electrode.[Polarised] This means
that it is very important which way round they are connected. If the capacitor
is subjected to voltage exceeding its working voltage, or if it is connected with
incorrect polarity, it may burst. It is extremely dangerous, because it can quite
literally explode. Make
absolutely no mistakes.
Generally, in the circuit
diagram, the positive
side is indicated by a
"+" (plus) symbol.
Electrolytic capacitors
range in value from
about 1µF to thousands
of µF. Mainly this type
of capacitor is used as a
ripple filter in a power
supply circuit, or as a
filter to bypass low
frequency signals, etc. Because this type
of capacitor is comparatively similar to
the nature of a coil in construction, it isn't
possible to use for high-frequency
circuits. (It is said that the frequency
characteristic is bad.)
The photograph on the left is an example
of the different values of electrolytic
capacitors in which the capacitance and
voltage differ.
From the left to right:
1µF (50V) [diameter 5 mm, high 12 mm]
47µF (16V) [diameter 6 mm, high 5 mm]
100µF (25V) [diameter 5 mm, high 11 mm]
220µF (25V) [diameter 8 mm, high 12 mm]
1000µF (50V) [diameter 18 mm, high 40 mm]
The size of the capacitor sometimes depends on the manufacturer. So the
sizes shown here on this page are just examples.
In the photograph to the right, the mark indicating the negative lead of the
component can be seen.
You need to pay attention to the polarity indication so as not to make a mistake
when you assemble the circuit.
Tantalum
Capacitors
Tantalum
Capacitors
are
electrolytic
capacitors
that is use
a material
called tantalum for the electrodes.
Large values of capacitance similar to aluminum electrolytic capacitors can be
obtained. Also, tantalum capacitors are superior to aluminum electrolytic
capacitors in temperature and frequency characteristics. When tantalum
powder is baked in order to solidify it, a crack forms inside. An electric charge
can be stored on this crack.
These capacitors have polarity as well. Usually, the "+" symbol is used to
show the positive component lead. Do not make a mistake with the polarity on
these types.
Tantalum capacitors are a little bit more expensive than aluminum electrolytic
capacitors. Capacitance can change with temperature as well as frequency, and
these types are very stable. Therefore, tantalum capacitors are used for circuits
which demand high stability in the capacitance values. Also, it is said to be
common sense to use tantalum capacitors for analog signal systems, because
the current-spike noise that occurs with aluminum electrolytic capacitors does
not appear. Aluminum electrolytic capacitors are fine if you don't use them for
circuits which need the high stability characteristics of tantalum capacitors.
The photograph on the left illustrates the tantalum capacitor.
The capacitance values are as follows, from the left:
0.33 µF (35V)
0.47 µF (35V)
10 µF (35V)
The "+" symbol is used to
show the positive lead of the
component. It is written on
the body.
Ceramic Capacitors
Ceramic capacitors are constructed with materials such as titanium acid barium
used as the dielectric. Internally, these capacitors are not constructed as a coil,
so they can be used in high frequency applications. Typically, they are used in
circuits which bypass high frequency signals to ground.
These capacitors have the shape of a disk. Their capacitance is comparatively
small.
The capacitor on the left is a 100pF capacitor with a diameter of about 3 mm.
The capacitor on the right side is printed with 103, so 10 x 10 3pF becomes
0.01 µF. The diameter of the disk is about 6 mm.
Ceramic capacitors have no polarity.
Ceramic capacitors should not be used for analog circuits, because they can
distort the signal.
Multilayer Ceramic Capacitors
The multilayer ceramic capacitor has a many-layered dielectric. These
capacitors are small in size, and have good temperature and frequency
characteristics.
Square wave signals
used in digital circuits can have a comparatively
high frequency component included.
This capacitor is used to bypass the high frequency to ground.
In the photograph, the capacitance of the component on the left is displayed as
104. So, the capacitance is 10 x 104 pF = 0.1 µF. The thickness is 2 mm, the
height is 3 mm, the width is 4 mm.
The capacitor to the right has a capacitance of 103 (10 x 103 pF = 0.01 µF).
The height is 4 mm, the diameter
of the round part is 2 mm.
These capacitors are not
polarized. That is, they have no
polarity.
Polystyrene Film Capacitors
In these devices, polystyrene film is used as the dielectric. This type of
capacitor is not for use in high frequency circuits, because they are constructed
like a coil inside. They are used well in filter circuits or timing circuits which
run at several hundred KHz or less.
The component shown on the left has a red color due to the copper leaf used
for the electrode. The silver color is due to the use of aluminum foil as the
electrode.
The device on the left has a height of 10 mm, is 5 mm thick, and is rated
100pF.
The device in the middle has a height of 10 mm, 5.7 mm thickness, and is
rated 1000pF.
The device on the right has a height of 24 mm, is 10 mm thick, and is rated
10000pF.
These devices have no polarity.
Electric Double Layer Capacitors (Super Capacitors)
This is a "Super Capacitor," which is quite a wonder.
The capacitance is 0.47 F (470,000 µF).
I have not used this capacitor in an actual
circuit.
Care must be taken when using a capacitor
with such a large capacitance in power
supply circuits, etc. The rectifier in the
circuit can be destroyed by a huge rush of
current when the capacitor is empty. For a
brief moment, the capacitor is more like a
short circuit. A protection circuit needs to be
set up.
The size is small in spite of capacitance. Physically, the diameter is 21 mm, the
height is 11 mm.
Care is necessary, because these devices do have polarity.
Polyester Film Capacitors
This capacitor uses thin polyester
film as the dielectric.
They are not high tolerance, but
they are cheap and handy. Their
tolerance is about ±5% to ±10%.
From the left in the photograph
Capacitance: 0.001 µF (printed
with 001K)
[the width 5 mm, the height 10
mm, the thickness 2 mm]
Capacitance: 0.1 µF (printed with 104K)
[the width 10 mm, the height 11 mm, the thickness 5mm]
Capacitance: 0.22 µF (printed with .22K)
[the width 13 mm, the height 18 mm, the thickness 7mm]
Care must be taken, because different manufacturers use different methods to
denote the capacitance values.
Here are some other polyester film capacitors.
Starting from the left
Capacitance: 0.0047 µF (printed
with 472K)
[the width 4mm, the height
6mm, the thickness 2mm]
Capacitance: 0.0068 µF (printed
with 682K)
[the width 4mm, the height
6mm, the thickness 2mm]
Capacitance: 0.47 µF (printed
with 474K)
[the width 11mm, the height
14mm, the thickness 7mm]
These capacitors have no polarity.
Polypropylene Capacitors
This capacitor is used when a higher tolerance is necessary than polyester
capacitors offer. Polypropylene film is used for the dielectric. It is said that
there is almost no change of capacitance in these devices if they are used with
frequencies of 100KHz or less.
The pictured capacitors have a tolerance of ±1%.
From the left in the photograph
Capacitance: 0.01 µF (printed with 103F)
[the width 7mm, the height 7mm, the thickness 3mm]
Capacitance: 0.022 µF (printed with 223F)
[the width 7mm, the height 10mm, the thickness 4mm]
Capacitance: 0.1 µF (printed with 104F)
[the width 9mm, the height 11mm, the thickness 5mm]
When I measured the capacitance of a 0.01 µF capacitor with the meter which
I have, the error was +0.2%.
These capacitors have no polarity.
Mica Capacitors
These capacitors use Mica for
the dielectric. Mica capacitors
have good stability because
their temperature coefficient is
small. Because their frequency
characteristic is excellent, they
are used for resonance circuits,
and high frequency filters. Also,
they have good insulation, and
so can be utilized in high voltage
circuits. It was often used for
vacuum tube style radio
transmitters, etc.
Mica capacitors do not have high
values of capacitance, and they
can be relatively expensive.
Pictured at the right are "Dipped
mica capacitors." These can
handle up to 500 volts.
The capacitance from the left
Capacitance: 47pF (printed with 470J)
[the width 7mm, the height 5mm, the thickness 4mm]
Capacitance: 220pF (printed with 221J)
[the width 10mm, the height 6mm, the thickness 4mm]
Capacitance: 1000pF (printed with 102J)
[the width 14mm, the height 9mm, the thickness 4mm]
These capacitors have no polarity.
Metallized Polyester Film Capacitors
These capacitors are a kind of a polyester film capacitor. Because their
electrodes are thin, they can be miniaturized.
From the left in the photograph
Capacitance: 0.001µF (printed with 1n. n means nano:10-9)
Breakdown voltage: 250V
[the width 8mm, the height 6mm, the thickness 2mm]
Capacitance: 0.22µF (printed with u22)
Breakdown voltage: 100V
[the width 8mm, the height 6mm, the thickness 3mm]
Capacitance: 2.2µF (printed with 2u2)
Breakdown voltage: 100V
[the width 15mm, the height 10mm, the thickness 8mm]
Care is necessary, because the component lead easily breaks off from these
capacitors. Once lead has come off, there is
no way to fix it. It must be discarded.
These capacitors have no polarity.
Variable Capacitors
Variable capacitors are used for adjustment etc. of frequency mainly.
On the left in the photograph is a "trimmer," which uses ceramic as the
dielectric. Next to it on the right is one that uses polyester film for the
dielectric.
The pictured components are meant to be mounted on a printed circuit board.
When adjusting the value of a variable capacitor, it is advisable to be careful.
One of the component's leads is connected to the adjustment screw of the
capacitor. This means that the value of the capacitor can be affected by the
capacitance of the screwdriver in your hand. It is better to use a special
screwdriver to adjust these components.
Pictured in the upper left photograph are variable capacitors with the following
specifications:
Capacitance: 20pF (3pF - 27pF measured)
[Thickness 6 mm, height 4.8 mm]
Their are different colors, as well. Blue: 7pF (2 - 9), white: 10pF (3 - 15),
green: 30pF (5 - 35), brown: 60pF (8 - 72).
In the same photograph, the device on the right has the following
specifications:
Capacitance: 30pF (5pF - 40pF
measured)
[The width (long) 6.8 mm, width
(short) 4.9 mm, and the height 5 mm]
The components in the photograph on
the right are used for radio tuners, etc.
They are called "Varicons" but this
may be only in Japan.
The variable capacitor on the left in the photograph, uses air as the dielectric. It
combines three independent capacitors.
For each one, the capacitance changed 2pF - 18pF. When the adjustment axis
is turned, the capacitance of all 3 capacitors change simultaneously.
Physically, the device has a depth of 29 mm, and 17 mm width and height.
(Not including the adjustment rod.)
There are various kinds of variable capacitor, chosen in accordance with the
purpose for which they are needed. The pictured components are very small.
To the right in the photograph is a variable capacitor using polyester film as
the dielectric. Two independent capacitors are combined.
The capacitance of one side changes 12pF - 150pF, while the other side
changes from 11pF - 70pF.
Physically, it has a depth of 11mm, and 20mm width and height. (Not
including the adjustment rod.)
The pictured device also has a small trimmer built in to each capacitor to allow
for precise adjustment up to 15pF.
Relays
The relay takes advantage of the fact that when electricity flows through a coil, it
becomes an electromagnet.
The electromagnetic coil attracts a steel plate, which is attached to a switch. So the
switch's motion (ON and OFF) is controled by the current flowing to the coil, or not,
respectively.
A very useful feature of a relay is that it can be used to electrically isolate different
parts of a circuit.
It will allow a low voltage circuit (e.g. 5VDC) to switch the power in a high voltage
circuit (e.g. 100 VAC or more).
The relay operates mechanically, so it can not operate at high speed.
There are many kind of relays. You can select one according to your needs.
The various things to consider when selecting a relay are its size, voltage and current
capacity of the contact points, drive voltage, impedance, number of contacts, resistance
of the contacts, etc.
The resistance voltage of the contacts
is the maximum voltage that can be
conducted at the point of contact in
the switch. When the maximum is
exceeded, the contacts will spark and
melt, sometimes fusing together. The
relay will fail. The value is printed on
the relay.
On the left in the photograph is a small relay with a coil
driving voltage of 12 VDC. It has two electrically
independant points of contact (switches.)
Although the resistance and permissible voltage and current
at the point of contact are indistinct, I think that it will
handle several hundred mA.
The relay on the right in the photograph can be used to
control a 100 VAC system. Its driving voltage is 3 VDC,
and if it is used to control an AC system, the maximum
resistance voltage is 125 VAC, and the permissible current
limit is 1A. If it is used to control a DC system, the maximum resistance voltage is
DC30V, and the permissible current limit is 2A. It has one contact only.
Both types of relay can be mounted on the PWB; the spacing of the component leads is
a multiple of 0.1 inches. It can also be mounted on the universal PWB.
The physical dimensions of the relay on the left are width 19.5 mm, height 10 mm, and
depth 10 mm.
The one that is on the right has the width 20 mm, height 15 mm, and depth 11 mm.
The relay pictured to the right is able to handle a little larger electric power.
Its driving voltage is 12 VDC, maximum resistance voltage is AC 240V, and the
permissible current limit is 5A in case of AC system. In a DC system, the maximum
resistance voltage is DC 28V, and the permissible current limit is 5A. It has 2 contacts.
This type of relay can not be mounted on the PWB. It needs a socket, and mounts on the
case or some other place with a screw.
The dimensions are width 22 mm, height 35 mm, and depth 20 mm.
Integrated Circuits
An integrated circuit contains
transistors, capacitors, resistors
and other parts packed in high
density on one chip.
Although the function is similar
to a circuit made with separate
components, the internal
structure of the components are
different in an integrated circuit.
The transistors, resistors, and
capacitors are formed very small,
and in high density on a
foundation of silicon. They are
formed by a variation of printing technology.
There are many kind of ICs, including special use ICs.
The top left device in the photograph is an SN7400. It contains 4 separate "2 input
NAND" circuits. There are 7 pins on each side, 14 pins total.
ICs in this form are called Dual In line Package (DIP).
When an IC has only one row of pins, it os called a Single In line Package (SIP).
The number of pins changes depending on the function of IC.
At the bottom left is an IC socket for use with 14 pin DIP ICs.
ICs can be attached directly to the printed circuit board with solder, but it's better
to use an IC socket, because you can easily exchange it should the IC fail.
On the top right is an LM386N audio amplifier. It can be used for amplification of
low frequency, low power signals. IT has 8 pins and the maximum output is
660mW.
On the bottom right is a TA7368P, which also is for amplification of low frequency
electric power. It has a maximum output of 1.1 watts.
It is a 9 pin SIP IC.
Common ICs
Below, the most common ICs are shown. (Those parts that I use most.)
For extensive details on each part, see the corresponding data sheet.
The part numbers of the SN74 series ICs are written with a 74, often followed by
LS or HC.
LS (Low power Shottky) indicates low power consumption. HC indicates the device
is High speed C-MOS (Complementary-Metal Oxide Semiconductor), and is also a
low power consumption IC.
The average current consumption for each type of chip is listed below.
The current shown is for when the device is in a LOW state output. In the case of
the LOW state output, current consumption is much greater than in the HIGH state
output.
SN7400
----- 22mA
SN74LS00 ----- 4.4mA
SN74HC00 ----- 0.02mA
Several kinds of ICs are not available in the LS or HC type. For example, SN7445
is not available in LS or HC. It is available only as SN7445, the normal type.
Name
Function
Vcc Pin Assign(Top View)
Remarks
SN74HC00 Quad 2 Input
+5V
2 input NAND
NAND
circuits
entered 4
pieces
SN74HC04 Hex Inverters
+5V
Inverter
circuit entered
6 pieces
Details
SN74LS42
BCD to
DECIMAL
Decoder
+5V
One of output
takes LOW
state serected
by the binary
input.
SN7445
O.C. BDC to
+5V
DECIMAL
Decoder/Driver
Open
collector type
of 7442
Max current
of output is
80mA.
SN74LS47
BCD to
+5V
Segment
Decoder/Driver
Front View
Driving IC of
‚Vsegments
LED.
Open
collector type
Max
resistance
voltage:15V
6 and 9 disply
type:
Related
74247
SN74HC73 Dual JK-FFs
With Clear
SN74LS90
+5V
Decade Counter +5V
2 pieces of
JK-FF
Asynchronous
2 + 5 counter.
Async preset :
9
Async clear
Related
74290
SN74HC93 4-Bit Binary
Counter
+5V
SN74HC12 Dual
+5V
3
Retriggaerable
Single Shot
74390
Asynchronous
2 + 8 counter.
Single shot
resister holds
the output in
the required
time from the
input states
goes to ON.
The output
holding time
corresponds
to
C(capacitor)
and
R(resistor)
connected to
the
Cext(External
capacitor) and
Rext(External
resistor)
respectivly.
SN74LS247 BCD to
+5V
Segment
Decoder/Driver
Front View
SN74LS290 Decade Counter +5V
6 and 9 disply
type:
Related 7447
This type is
the same as
the SN7490,
with a
different
layout of pins.
Related
7490
SN74HC39 Dual Decade
0
Counters
+5V
74390
Type that
inserted 2
SN7490.
Presetting 9 is
omitted .
Related
7490
74290
4040B
12Bit Binary
Counter
(CMOS)
+5V
4541B
Progarammable +5V
Oscillator/Time
r
(CMOS)
NE555
Timer
+4.5
to
+16
V
12-stage
Binary
counter.
It has a clear
function.
Counts
downward
with an
external clock
pulse.
Programmabl
e 16 stage
binary
counter.
Used in RC
oscillation
circuits,
power reset,
output control
circuits.
Tap outputs of
8, 10, 13, 16
bits are
possible by the
control
terminal.
Max
frequency:
500kHz
Temperature
drift:
0.005%/°C.
Max output
current:
200mA.
Delay time
setting
:several micro
sec to several
hours
Max output:
660mW
Load: 8 to 32ohm
Waiting
current: 4mA
Max output:
1.25W
Load: 8 to 32ohm
Waiting
current: 4mA
LM386N-1 Low frequency
electric power
amplifier
+4 to
12V
LM386N-4 Low frequency
electric power
amplifier
+5 to
18V
TA7368P
Low frequency
electric power
amplifier
+2 to
+10
V
Max output:
1.1W
Load: 4 to 16ohm
uPC319
Voltage
comparator
5 to
18V
Standard
general use
comparator
with single
power
supply/dual
power supply
operation
±5
to
±18V
Other
compatible
ICs
LM319
7975
Multi-melody
IC
(CMOS)
+1.5
to
+3V
NJM319
AN1319
Melody IC
that includes 8
preprogrammed
melodies.
It has 2 sound
resources and
a settable
envelope.
Title
GreenSleeves
Fur Elise
Heavenly
Creatures
Ich bin ein
musikante
Valse
Favorite
Holderia
Amaryllis
Home On
The Range
Three Terminal Voltage Regulator
It is very easy to get stabilized voltage for ICs by
using a three terminal voltage regulator.
The power supply voltage for a car is +12V - +14V.
At this voltage, some ICs can not operate directly
except for the car component ICs. In this case, a three
terminal voltage regulator is necessary to get the
required voltage.
The three terminal voltage regulator outputs
stabilized voltage at a lower level than the higher input voltage. A voltage
regulator cannot put out higher voltage than the input voltage. They are
similar in appearance to a transistor.
On the left in the photograph is a 78L05. The size and form is similar to a
2SC1815 transistor.
The output voltage is +5V, and the maximum output
current is about 100mA.
The maximum input voltage is +35V. (Differs by
manufacturer.)
On the right is a 7805. The output voltage is +5V, and
maximum output current is 500mA to 1A. (It depends on
the heat sink used)
The maximum input voltage is also +35V.
There are many types with different output voltages.
5V, 6V, 7V, 8V, 9V, 10V, 12V, 15V, 18V
Component Lead of Three Terminal Voltage
Regulator
Because the component leads differ between kinds of
regulators,
you need to confirm the leads with a datasheet, etc.
Example of 78L05
Part number is printed on the flat face of the regulator, and indicates the front.
Right side : Input
Center : Ground
Left side : Output
Example of 7805
Part number is printed on the flat face of the regulator, and indicates the front.
Right side : Output
Center : Ground
Left side : Input
Opposite from 78L05.
MT 8870 DTMF decoder:
IC MT8870/KT3170 serves as DTMF decoder. This IC takes DTMF signal
coming via telephone line and converts that signal into respective BCD number. It
uses same oscillator frequency used in the remote section so same crystal oscillator
with frequency of 3.85M Hz is used in this IC.
Working of IC MT8870:
The MT-8870 is a full DTMF Receiver that integrates both band split filter and
decoder functions into a single 18-pin DIP. Its filter section uses switched capacitor
technology for both the high and low group filters and for dial tone rejection. Its
decoder uses digital counting techniques to detect and decode all 16 DTMF tone pairs
into a 4-bit code. External component count is minimized by provision of an onchip differential input amplifier, clock generator, and latched tri-state interface bus.
Minimal external components required include a low-cost 3.579545 MHz crystal, a
timing resistor, and a timing capacitor. The MT-8870-02 can also inhibit the decoding
of fourth column digits.
MT-8870 operating functions include a band split filter that separates the high
and low tones of the received pair, and a digital decoder that verifies both the
frequency and duration of the received tones before passing the resulting 4-bit code to
the output bus.
The low and high group tones are separated by applying the dual-tone signal to the
inputs of two 6th order switched capacitor band pass filters with bandwidths that
correspond to the bands enclosing the low and high group tones.
Figure (F). Block diagram of IC MT8870
The filter also incorporates notches at 350 and 440 Hz, providing excellent dial
tone rejection. Each filter output is followed by a single-order switched capacitor
section that smoothes the signals prior to limiting. Signal limiting is performed by
high gain comparators provided with hysteresis to prevent detection of unwanted lowlevel signals and noise. The MT-8870 decoder uses a digital counting technique to
determine the frequencies of the limited tones and to verify that they correspond to
standard DTMF frequencies. When the detector recognizes the simultaneous presence
of two valid tones (known as signal condition), it raises the Early Steering flag (ESt).
Any subsequent loss of signal condition will cause ESt to fall. Before a decoded tone
pair is registered, the receiver checks for valid signal duration (referred to as
character- recognition-condition). This check is performed by an external RC time
constant driven by ESt. A short delay to allow the output latch to settle, the delayed
steering output flag (StD) goes high, signaling that a received tone pair has been
registered. The contents of the output latch are made available on the 4-bit output bus
by raising the three state control input (OE) to logic high. Inhibit mode is enabled by a
logic high input to pin 5 (INH). It inhibits the detection of 1633 Hz.
The output code will remain the same as the previous detected code. On the M8870 models, this pin is tied to ground (logic low).
The input arrangement of the MT-8870 provides a differential input operational
amplifier as well as a bias source (VREF) to bias the inputs at mid-rail. Provision is
made for connection of a feedback resistor to the op-amp output (GS) for gain
adjustment.
The internal clock circuit is completed with the addition of a standard 3.579545 MHz
crystal.
The input arrangement of the MT-8870 provides a differential input operational
amplifier as well as a bias source (VREF) to bias the inputs at mid-rail. Provision is
made for connection of a feedback resistor to the op-amp output (GS) for gain
adjustment.
The internal clock circuit is completed with the addition of a standard 3.579545
MHz crystal.
IC NE 555 timer:
The NE555 is an integrated circuit that capable of producing accurate timing
pulses. This IC is used as a multivibrater By using this IC we can construct two types
of multivibrater, monostable and astable. The monostable multivibrater produces a
single pulse when a triggering pulse is applied to its triggering input. The astable
multivibrater produces a train of pulses depending on the Resister-Capacitor
combination wired around it.
With a monostable operation, the time delay is controlled by one external
resistor and one capacitor connected between Vcc-Discharge (R), and ThresholdGround (C). With an astable operation, the frequency and pulse width are produced by
two external resistors and one capacitor connected between Vcc-Discharge (R),
Discharge-Threshold (R), and Threshold-Ground (C).
Figure J. IC NE 555
74154 4-16 line decoder/demultiplexer:
IC 74154 is a 4-16 line decoder, it takes the 4 line BCD input and selects
respective output one among the 16 output lines . It is active low output IC so when
any output line is selected it is indicated by active low signal, rest of the output lines
will remain active high. This 4-line-to-16-line decoder utilizes TTL circuitry to
decode four binary-coded inputs into one of sixteen mutually exclusive outputs when
both the strobe inputs, G1 and G2, are low. The demultiplexing function is performed
by using the 4 input lines to address the output line, passing data from one of the
strobe inputs with the other strobe input low. When either strobe input is high, all
outputs are high. These demultiplexer are ideally suited for implementing highperformance memory decoders.
Figure G. IC 74154 4-16 line decoder
All inputs are buffered and input clamping diodes are provided to minimize
transmission-line effects and thereby simplify system design.
TRUTH TABLE:
74126 Tri - State Buffer:
This IC is a tri state buffer contains four independent gates each of which
performs a non-inverting buffer function. The outputs have the 3-STATE feature.
When control signal is at high state, the outputs are nothing but the data present at its
input terminals. When control signal is at low state, the outputs are held at high
impedance state. So no output will be available at the output terminal.
Figure H. IC 74126
IC 7474 D-flip-flop:
IC 7474 is a conventional D-flip-flop IC. This IC consists of two D
flip-flops. These flip-flops are used to latch the data that present at its input terminal.
Each flip-flop has one data, one clock, one clear, one preset input terminals.
(Above figure shows a single D-flip-flop)
IC 7447 BCD - seven segment decoder:
The DM74LS47 accepts four lines of BCD (8421) input data, generates their
complements internally and decodes the data with seven AND/OR gates having opencollector outputs to drive indicator segments directly. Each segment output is
guaranteed to sink 24mA in the ON (LOW) state and withstand 15V in the OFF
(HIGH) state with a maximum leakage current of 250 mA. Auxiliary inputs provided
blanking, lamp test and cascadable zero-suppression functions.
Figure I. IC 7447 BCD - seven segment decoder
ULN2003A-ULN2004A
..SEVEN DARLINGTONS PER PACKAGE OUTPUT CURRENT 500mA PER
DRIVER .(600mA PEAK) .OUTPUT VOLTAGE 50V INTEGRATED
SUPPRESSION DIODES FOR .INDUCTIVE LOADS OUTPUTS CAN BE
PARALLELED FOR .HIGHER CURRENT .TTL/CMOS/PMOS/DTL
COMPATIBLE INPUTS INPUTS PINNED OPPOSITE OUTPUTS TO
SIMPLIFY LAYOUT
DESCRIPTION
The ULN2001A, ULN2002A, ULN2003 and ULN2004A are high voltage, high
current darlington arrays each containing seven open collector darlington pairs with
common emitters. Each channel rated at 500mA and can withstand peak currents of
600mA. Suppression diodes are included for inductive load driving and the inputs are
pinned opposite the outputs to simplify board layout.
The four versions interface to all common logic families
:
ULN2001A General Purpose, DTL, TTL, PMOS, CMOS
ULN2002A 14-25V PMOS
ULN2003A 5V TTL, CMOS
ULN2004A 6–15V CMOS, PMOS
These versatile devices are useful for driving a wide range of loads including
solenoids, relays DC motors, LED displays filament lamps, thermal printheads and
high power buffers.
The ULN2001A/2002A/2003A and 2004A are supplied in 16 pin plastic DIP
packages with a copper leadframe to reduce thermal resistance. They are available
also in small outline package (SO-16) as ULN2001D/2002D/2003D/2004D.
DIP16
ORDERING NUMBERS: ULN2001A/2A/3A/4A
SO16
ORDERING NUMBERS: ULN2001D/2D/3D/4D