RELAY

Relays are one of the oldest, simplest, and yet, easiest and most useful devices. Before

the advent of the mass produced transistor, computers were made from either relays or

vacuum tubes, or both.

A relay, quite simply, is a small machine consisting of an electromagnet (coil), a switch,

and a spring. The spring holds the switch in one position, until a current is passed through

the coil. The coil generates a magnetic field which moves the switch. It's that simple. You

can use a very small amount of current to activate a relay, and the switch can often handle

a lot of current.

The relay we are going to look at is the Bosch 5 pin relay. Bosch is a German

manufacturing conglomerate (who also happen to own Bosch Telekom and Blaupunkt),

but they are not the only manufacturer of this relay. There are several other companies

such as Siemens (stop laughing) and Potter & Brumfield. I don't know why they call it

the Bosch type relay, but dammit, I don't give a shit either. The Bosch 5 pin relay is the

most widely used and versatile relay, and it can handle up to 30 amps, which is more than

suitable for most applications.

Relay’s Circuit

Relay With Coil

555 TIMER MONOTABLE IC

The 555 timer IC is an integrated circuit implementing a variety of timer and multivibrator

applications. Its ease of use, low price and good stability, using fewer external components and

less power.

Depending on the manufacturer, the standard 555 package includes over 20 transistors,2 diodes

and 15 resistors on a silicon chip installed in an 8-pin mini dual-in-line package(DIP-8).

The 555 has three operating modes:

Monostable mode: in this mode, the 555 function as a “one-shot”. Applications include timers,

missing pulse detection, bouncefree switches, touch switches, frequency divider, capacitance

measurement, pulse-width modulation etc

Astable-free running mode: the 555 can operate as an oscillator. Uses include LED and lamp

flashers, pulse generation, logic clocks, tone generation, security alarms, pulse position

modulation etc.

Bistable mode or Schmitt trigger: the 555 can operate as a flip-flop, if the DIS pin is not

connected and no capacitor is used. Uses include bouncefree latched switches etc.

ENCODER IC

An encoder is a device, circuit, transducer, software program, algorithm or person that converts

information from one format or code to another, for the purposes of standardization, speed,

secrecy, security, or saving space by shrinking size.The HT 12E encoder ICs are series of CMOS

LSIs for remote control system applications. They are capable of encoding 12 bit of information

which consists of N address bits and 12-N data bits. Each address/data input is externally trinary

programmable if bonded out.

The HT 12D ICs are series of CMOS LSIs for remote control system applications. This ICs are

paired with each other. For proper operation a pair of encoder/decoder with the same number of

address and data format should be selected. The decoder receive the serial address and data from

its corresponding decoder, transmitted by a carrier using an RF transmission medium and gives

output to the output pins after processing the data.

RF TRANSMITTER MODULE

Radio frequency transmitters are widely used in radio frequency communications systems. With

the increasing availability of efficient, low cost electronic modules, mobile communication

systems are becoming more and more widespread. Wireless communication systems, including

cellular phones, paging devices, personal communication services systems, and wireless data

networks, have become ubiquitous in society.

Generally, a radio transmitter and receiver is used for performing a radio transmission and

receiving operation, where by a high frequency signal outputted from a modulator is transmitted

to an antenna of the radio transmitter and is transmitted there form to a remote radio transmitter

and receiver, or the thusly transmitted signal is received through another antenna. The

transmitting baseband signal is subjected to a predetermined signal process, input to a modulator,

which modulates a carrier wave signal. The modulated carrier wave signal is converted into a

radio frequency by a transmitting radio frequency circuit and amplified to a predetermined

transmitting power, and transmitted to the base station from the antenna via the duplexer.

RF RECEIVER MODULE:

This compact radio frequency receiver module is suitable foe remote control or telemetry

applications. The double sided circuit board is pre-populated with surface mount devices and is

tuned to 433 MHz. no module assembly or adjustments are required. RF receiver module RX433

receivers RF control signals from the 8 channel RF remote control transmitter K8058 and

performs as an RF receiver interface when used on the 8 channel remote control relay board

K8056 . RF receiver module RX433 is a highly sensitive passive design that is easy to implement

with a low external parts count.

RF remote receiver module RX433 can also be used with 433 MHz RF transmitter TX433N for

your custom remote control or telemetry requirements.

DECODER IC

A decoder is a device which does the reverse of an encoder, undoing the encoding so that the

original information can be retrieved. The same method used to encode is usually just reversed in

order to decode.

In digital electronics, a decoder can take the form of a multiple-input, multiple-output logic

circuit that converts coded inputs into coded outputs, where the input and output codes are

different. e.g. n-to-2, binary-coded decimal decoders. Enable inputs must be on for the decoder to

function, otherwise its outputs assume a single “disabled” output codeword. Depending is

necessary in applications such as data multiplexing, 7 segment display and memory address

decoding.

The example decoder circuit would be an AND gate is HIGH (1) only when all its input are

HIGH. Such output is called as “active high output”. If instead of AND gate, the NAND gate

connected the output will be LOW (0) only when all its inputs are “high”. Such output is called as

“active low output”.

OTHER COMPONENT’S

RESISTOR

A resistor is a two-terminal electronic component designed to oppose an electric current

by producing a voltage drop between its terminals in proportion to the current, that is, in

accordance with Ohm's law: V = IR. The resistance R is equals to the voltage drop V

across the resistor divided by the current I through the resistor.

Resistors are characterized primarily by their resistance and the power they can dissipate.

Other characteristics include temperature coefficient, noise, and inductance. Practical

resistors can be made of resistive wire, and various compounds and films, and they can

be integrated into hybrid and printed circuits.

Size, and position of leads are relevant to equipment designers; resistors must be

physically large enough not to overheat when dissipating their power. Variable resistors,

adjustable by changing the position of a tapping on the resistive element, and resistors

with a movable tap ("potentiometers"), either adjustable by the user of equipment or

contained within, are also used.

Resister symbol (American) resister symbol (Europe)

UNITS

The ohm (symbol: Ω) is the SI unit of electrical resistance, named after Georg Ohm. The

most commonly used multiples and submultiples in electrical and electronic.

Axial-Lead Resistors On Tape

COLOUR CODES VALUES

There are many different types of Resistors available and that they can be used in both

electrical and electronic circuits to control the flow of current and voltage in many

different ways. But in order to do this the actual Resistor needs to have some form of

"Resistance" value, and resistors are available in a range of different resistance values

from fractions of an Ohm (Ω) to millions of Ohms.

Obviously, it would be impractical to have available resistors of every possible value for

example, 1Ω, 2Ωs, 3Ωs, 4Ωs etc because literally hundreds of thousands, if not millions

of resistors would exist. Instead, resistors are manufactured in preferred values with their

"Resistance" rating printed onto their body.

The resistance value, tolerance, and watt rating of the resistor are generally printed onto

the body of the resistor when it is big enough to read the print, such as large power

resistors.

When resistors are small such as 1/4W Carbon and Film types, these specifications must

be shown in some other manner as the print would be too small to read. So to overcome

this, small resistors use coloured paint bands to indicate both their resistive value and

their tolerance with the physical size of the resistor indicating its wattage rating.

An International resistor colour coding scheme was developed many years ago as a

simple way of identifying resistor values. It consists of coloured rings (in spectral order)

whose meanings are illustrated below

The Resistor Colour Code Table

Colour Digit Multiplier Tolerance

Black 0 1  

Brown 1 10 ± 1%

Red 2 100 ± 2%

Orange 3 1K  

Yellow 4 10K  

Green 5 100K ± 0.5%

Blue 6 1M ± 0.25%

Violet 7 10M ± 0.1%

Grey 8    

White 9    

Gold   0.1 ± 5%

Silver   0.01 ± 10%

None     ± 20%

CALCULATING RESISTOR VALUES

The "left-hand" or the most significant colored band is the band which is nearest to a

connecting lead with the color coded bands being read from left-to-right as follows;

Digit, Digit, Multiplier = Colour, Colour x 10 colour  in Ohm's (Ω's)

For example, a Resistor has the following colored markings;

Yellow Violet Red = 4 7 2 = 4 7 x 10 2 = 4700Ω or 4k7.

CAPACITOR

Practical capacitors are available commercially in many different forms. The type of

internal dielectric, the structure of the plates and the device packaging all strongly affect

the characteristics of the capacitor, and its applications.

Capacitors

DIELETRIC MATERIALS

Most types of capacitor include a dielectric spacer, which increases their capacitance.

However, low capacitance devices are available with a vacuum between their plates,

which allows extremely high voltage operation and low losses. Variable capacitors with

their plates open to the atmosphere were commonly used in radio tuning circuits. Later

designs use polymer foil dielectric between the moving and stationary plates, with no

significant air space between them.

Several solid dielectrics are available, including paper, plastic, glass, mica and ceramic

materials. Paper was used extensively in older devices and offers relatively high voltage

performance.

However, it is susceptible to water absorption, and has been largely replaced by plastic

film capacitors. Plastics offer better stability and aging performance, which makes them

useful in timer circuits, although they may be limited to low operating temperatures and

frequencies.

Ceramic capacitors are generally small, cheap and useful for high frequency applications,

although their capacitance varies strongly with voltage, and they age poorly. They are

broadly categorized as Class 1 dielectrics, which have predictable variation of

capacitance with temperature or Class 2 dielectrics,

This can operate at higher voltage. Glass and mica capacitors are extremely reliable,

stable and tolerant to high temperatures and voltages, but are too expensive for most

mainstream applications.

Ceramic Capacitor

From left: multilayer ceramic, ceramic disc, multilayer polyester film, tubular ceramic,

polystyrene, metalized polyester film, aluminum electrolytic. Electrolytic capacitors use

an aluminum or tantalum plate with an oxide dielectric layer. The second electrode is a

liquid electrolyte, connected to the circuit by another foil plate.

Electrolytic capacitors offer very high capacitance but suffer from poor tolerances, high

instability, gradual loss of capacitance especially when subjected to heat, and high

leakage current.

The conductivity of the electrolyte drops at low temperatures, which increases equivalent

series resistance. While widely used for power-supply conditioning, poor high-frequency

characteristics make them unsuitable for many applications.

Different Capacitors

Capacitor packages

SMD ceramic at top left; SMD tantalum at bottom left; through-hole tantalum at top

right; through-hole electrolytic at bottom right. Major scale divisions are cm.

DIODES

In electronics, a diode is a two-terminal device (thermionic diodes may also have one or

two ancillary terminals for a heater).

Diodes have two active electrodes between which the signal of interest may flow, and

most are used for their unidirectional electric current property. The varicap diode is used

as an electrically adjustable capacitor.

Diode

The directionality of current flow most diodes exhibit is sometimes generically called the

rectifying property. The most common function of a diode is to allow an electric current

to pass in one direction (called the forward biased condition) and to block the current in

the opposite direction (the reverse biased condition).

CURRENT–VOLTAGE CHARACTERISTIC

A semiconductor diode's current–voltage characteristic, or I–V curve, is related to the

transport of carriers through the so-called depletion layer or depletion region that exists at

the p-n junction between differing semiconductors.

When a p-n junction is first created, conduction band (mobile) electrons from the N-

doped region diffuse into the P-doped region where there is a large population of holes

(places for electrons in which no electron is present) with which the electrons

"recombine" When a mobile electron recombines with a hole, both hole and electron

vanish, leaving behind an immobile positively charged donor on the N-side and

negatively charged acceptor on the P-side. The region around the p-n junction becomes

depleted of charge carriers and thus behaves as an insulator.

If an external voltage is placed across the diode with the same polarity as the built-in

potential, the depletion zone continues to act as an insulator, preventing any significant

electric current flow.

I–V Characteristics of a P-N Junction Diode (Not To Scale).

This is the reverse bias phenomenon. However, if the polarity of the external voltage

opposes the built-in potential, recombination can once again proceed, resulting in

substantial electric current through the p-n junction. For silicon diodes, the built-in

potential is

Approximately 0.6 V. Thus, if an external current is passed through the diode, about 0.6

V will be developed across the diode such that the P-doped region is positive with respect

to the N-doped region and the diode is said to be "turned on" as it has a forward bias.

At very large reverse bias, beyond the peak inverse voltage or PIV, a process called

reverse breakdown occurs which causes a large increase in current that usually damages

the device permanently. The avalanche diode is deliberately designed for use in the

avalanche region. In the zener diode, the concept of PIV is not applicable.

A zener diode contains a heavily doped p-n junction allowing electrons to tunnel from the

valence band of the p-type material to the conduction band of the n-type material, such

that the reverse voltage is "clamped" to a known value (called the zener voltage), and

avalanche does not occur.

Both devices, however, do have a limit to the maximum current and power in the

clamped reverse voltage region. Also, following the end of forward conduction in any

diode, there is reverse current for a short time. The device does not attain its full blocking

capability until the reverse current ceases.

The second region, at reverse biases more positive than the PIV, has only a very small

reverse saturation current. In the reverse bias region for a normal P-N rectifier diode, the

current through the device is very low (in the µA range).

The third region is forward but small bias, where only a small forward current is

conducted.

As the potential difference is increased above an arbitrarily defined "cut-in voltage" or

"on-voltage" or "diode forward voltage drop (Vd)", the diode current becomes appreciable

(the level of current considered "appreciable" and the value of cut-in voltage depends on

the application), and the diode presents a very low resistance.

The current–voltage curve is exponential. In a normal silicon diode at rated currents, the

arbitrary "cut-in" voltage is defined as 0.6 to 0.7 volts. The value is different for other

diode types — Schottky diodes can be as low as 0.2 V and red light-emitting diodes

(LEDs) can be 1.4 V or more and blue LEDs can be up to 4.0 V.

At higher currents the forward voltage drop of the diode increases. A drop of 1 V to 1.5 V

is typical at full rated current for power diodes.

DiodeZener

diode

Schottky

diode

Tunnel

diode

Light-emitting

diodePhotodiode Varicap Silicon controlled rectifier

Figure 2.22 Some Diode Symbols

ELECTRIC SWITCHES

Tactile Switch: tactile switch uses a clicking sound for distinctive feel to make it

easy to tell whether the switch is in on or off position. This is also known as a

push to on switch. These switches have tendency to produce bounce when contact

opens or closes. Bouncing duration increases with increase in operation time.

Switch

2.6.5 VOLTAGE REGULATOR (78xx)

An Assortment of 78XX ICs

The Voltage Regulator (78xx) (also sometimes known as LM78xx) series of devices is a

family of self-contained fixed linear voltage regulator integrated circuits. The 78xx

family is a very popular choice for many electronic circuits which require a regulated

power supply, due to their ease of use and relative cheapness.

When specifying individual ICs within this family, the xx is replaced with a two-digit

number, which indicates the output voltage the particular device is designed to provide

(for example, the 7805 has a 5 volt output, while the 7812 produces 12 volts).

The 78xx line is positive voltage regulators, meaning that they are designed to produce a

voltage that is positive relative to a common ground. There is a related line of 79xx

devices which are complementary negative voltage regulators. 78xx and 79xx ICs can be

used in combination to provide both positive and negative supply voltages in the same

circuit, if necessary.

78xx ICs have three terminals and are most commonly found in the TO220 form factor,

although smaller surface-mount and larger TO3 packages are also available from some

manufacturers. These devices typically support an input voltage which can be anywhere

from a couple of volts over the intended output voltage, up to a maximum of 35 or 40

volts, and can typically provide up to around 1 or 1.5 amps of current (though smaller or

larger packages may have a lower or higher current rating).

LED

A light when electrically biased in the forward direction light-emitting diode (LED) is a

semiconductor device that emits incoherent narrow-spectrum. This effect is a form of

electroluminescence. The colour of the emitted light depends on the composition and

condition of the semiconducting material used, and can be infrared, visible or near-

ultraviolet. Rubin Braunstein of the Radio Corporation of America first reported on

infrared emission from gallium arsenide (GaAs) and other semiconductor alloys in 1955.

LEDs

In the case of LEDs, the conductor material is typically aluminum-gallium-arsenide

(AlGaAs). In pure aluminum-gallium-arsenide, all of the atoms are bonded perfectly to

their neighbors, leaving no free electrons (negatively-charged particles) to conduct

electric current. In doped material, additional atoms change the balance, either adding

free electrons or creating holes where electrons can go. Either of these additions make the

material more conductive.

A semiconductor with extra electrons is called N-type material, since it has extra

negatively-charged particles. In N-type material, free electrons move from a negatively-

charged area to a positively charged area.

COLOURS OF LEDS

LEDs are available in red, orange, amber, yellow, green, blue and white. Blue and white

LEDs are much more expensive than the other colors. The color of an LED is determined

by the semiconductor material, not by the coloring of the 'package' (the plastic body).

LEDs of all colors are available in uncolored packages which may be diffused (milky) or

clear (often described as 'water clear'). The colored packages are also available as

diffused or clear.as:

MONO-COLOUR LEDS

BI-COLOUR LEDS

TRI-COLOUR LED