ANÁLISIS DE LA COMPETENCIA POR CICLO DE LA VIDA DE LOS PRODUCTOS

Since all electronic circuits work only with low dc voltage it needs a power supply unit to provide the appropriate voltage supply. This unit consists of a transformer, rectifier, filter and regulator. AC voltage typically 230v is connected to the transformer that steps the AC voltage down to the level to the desired AC voltage. A diode rectifier then provides a full wave rectified voltage that is initially filtered by a simple capacitive filter to produce a DC voltage. This resulting DC voltage usually has some ripple or AC voltage variations.

5.3 DTMF

What are DTMF tones ?

There are companies which have a telephone system which can be controlled by DTMF tones (for instance: pager systems). To use these services you need to have a phone which is capable to send DTMF tones.

DTMF stands for Dual Tone Multiple Frequency. When a key on the phone is pressed during a phone call this character is send using DTMF. The following characters can be send using DTMF: 0,1,2,3,4,5,6,7,8,9,A,B,C,D,* and #.

The DTMF keypad is laid out in a 4�4 matrix, with each row representing a low frequency, and each column representing a high frequency (see table). Pressing a single key such as '1' will send a sinusoidal tone of the two frequencies 697 and 1209 hertz (Hz). The original keypads had levers inside, so each button activated two contacts. The multiple tones are the reason for calling the system multifrequency. These tones are then decoded by the switching center to determine which key was pressed.

1209Hz 1336Hz 1477Hz 1633Hz

697Hz 1 2 3 A

770 4 5 6 B

1209Hz 1336Hz 1477Hz 1633Hz

941Hz * 0 # D

How to send DTMF tones

Of course you can send DTMF phones using your fixed line phone or cellphone, but if you want to automate the sending of these tones over a phone connection, it becomes difficult because most modems can only send DTMF to dial a number, but when the connection is made, there is no way to send these tones. Some GSM modems do have this featuresuch as the WaveCom and the Multitech GSM modems.

5.4 Relay driver and relay:

U L N 2 0 0 3 1 2 V 1 2 3 4 R e l a y 9 8 p r o t o t y p e m o t o r w h e e l 1 6 1 2 V

A ULN2003 is an Integrated Circuit (IC) chip with a High Voltage/High Current Darlington Transistor Array. It allows you to interface TTL signals with higher voltage/current loadsA TTL signal operates from 0-5V, with everything between 0.0 and 0.8V considered "low" or off, and 2.2 to 5.0V being considered "high" or on. The maximum power available on a TTL signal depends on the type, but generally does not exceed 25mW (~5mA @ 5V), so it is not useful for providing power to something like a relay coil. Computers and other electronic devices frequently generate TTL signals. On the output side the ULN2003 is generally rated at 12v, so it can operate small loads directly. Alternatively, it is frequently used to power the coil of one or more relays, which in turn allow even higher voltages/currents to be controlled by the low level signal. In electrical terms, the ULN2003 uses the low level (TTL) signal to switch on/turn off the higher voltage/current signal on the output side.

Relay:

Relays are components which allow a low-power circuit to switch a relatively high current on and off, or to control signals that must be electrically isolated from the controlling circuit itself. To make a relay operate, you have to pass a suitable pull-in and

holding current (DC) through its energising coil. And generally relay coils are designed to operate from a particular supply voltage often 12V or 5V, in the case of many of the small relays used for electronics work. In each case the coil has a resistance which will draw the right pull-in and holding currents when its connected to that supply voltage. So the basic idea is to choose a relay with a coil designed to operate from the supply voltage you.re using for your control circuit (and with contacts capable of switching the currents you want to control), and then provide a suitable .relay driver. circuit so that your low- power circuitry can control the current through the relays coil.

6. PCB DESIGN

Design and Fabrication of Printed circuit boards 6.1 INTRODUCTION:

Printed circuit boards, or PCBs, form the core of electronic equipment domestic and industrial. Some of the areas where PCBs are intensively used are computers, process control, telecommunications and instrumentation.

6.2 MANUFATCURING:

The manufacturing process consists of two methods; print and etch, and print, plate and etch. The single sided PCBs are usually made using the print and etch method. The double sided plate through – hole (PTH) boards are made by the print plate and etch method.

The production of multi layer boards uses both the methods. The inner layers are printed and etch while the outer layers are produced by print, plate and etch after pressing the inner layers.

6.3 SOFTWARE:

The software used in our project to obtain the schematic layout is MICROSIM.

6.4 PANELISATION:

Here the schematic transformed in to the working positive/negative films. The circuit is repeated conveniently to accommodate economically as many circuits as possible in a

panel, which can be operated in every sequence of subsequent steps in the PCB process. This is called penalization. For the PTH boards, the next operation is drilling.

6.5 DRILLING:

PCB drilling is a state of the art operation. Very small holes are drilled with high speed CNC drilling machines, giving a wall finish with less or no smear or epoxy, required for void free through whole plating.

6.6 PLATING:

The heart of the PCB manufacturing process. The holes drilled in the board are treated both mechanically and chemically before depositing the copper by the electro less copper platting process.

6.7 ETCHING:

Once a multiplayer board is drilled and electro less copper deposited, the image available in the form of a film is transferred on to the outside by photo printing using a dry film printing process. The boards are then electrolytic plated on to the circuit pattern with copper and tin.

The tin-plated deposit serves an etch resist when copper in the unwanted area is removed by the conveyor’s spray etching machines with chemical etch ants. The etching machines are attached to an automatic dosing equipment, which analyses and controls etch ants concentrations

6.8 SOLDERMASK:

Since a PCB design may call for very close spacing between conductors, a solder mask has to be applied on the both sides of the circuitry to avoid the bridging of conductors. The solder mask ink is applied by screening. The ink is dried, exposed to UV, developed in a mild alkaline solution and finally cured by both UV and thermal energy.

6.9 HOT AIR LEVELLING:

After applying the solder mask, the circuit pads are soldered using the hot air leveling process. The bare bodies fluxed and dipped in to a molten solder bath. While removing the board from the solder bath, hot air is blown on both sides of the board through air knives in the machines, leaving the board soldered and leveled. This is one of the common finishes given to the boards. Thus the double sided plated through whole printed circuit board is manufactured and is now ready for the components to be soldered.

7 SOFTWARE TOOLS