vb.net My SQL Tutorial 1

hi all this is the first tutorial of 7 series vb.net My SQL Tutorial..happy reading :) 
vb.net My SQL Tutorial 1

UPS

Of late, you use a number of things which run by electricity. Frequent power cuts leave you paralyzed therefore the idea of uninterruptible power supplies (UPS) came in existence. The uninterruptible power supplies are designed to avoid power trips and cuts as brings power supply as soon as it experiences power failure. This gadget can be seen everywhere from houses to offices to industrial plants to hospitals. Ranging from 200VA to 4.8mVA, most of UPS in the country comprise of a battery pack and an input and output phase.

Knowing extensively about uninterruptible power supplies

Also recognized as a continuous power supplies or a battery backup, uninterruptible power supplies are devices assist in maintaining a continuous supply of electric power to connected devices and equipments by supplying power from a separate source when utility power gets failed. UPS is popular than standby generator as the generator does not provide instant power for a momentary power interruption.    

Different types of UPS

There are three types of uninterruptible power supplies available in the UK include:

•    Online or Double Conversion
•    Line Interactive
•    Offline (or Passive Standby)

The type of UPS depends upon the requirements of customers. Market is packed from low budget to high budget devices; you can buy according to your use.

Knowing about the components of the device

Your UPS and other electronic devices are comprised of components such rectifier, charger, battery, inverter, maintenance bypass and static switch which make them work effectively and efficiently. Each component has its own area of specification. Comprising of a series of battery backups, they employ DC to convert it to AC and thus it is useful for your appliances.   

Why are online stores preferred for uninterruptible power supplies?

The internet has been considered as an economical option for buying UPSes and their accessories. Apart from cost effective, it brings exclusive and vital products for wide range of customers. After searching a reliable and genuine online UPS store, you need to fill in its online order form and send it to the mentioned address for further course of action. So, why are you thinking of?

Building your own computer

Have you ever dream to building your own computer? Actually buying a motherboard and a case ­along with all the supporting stuff and assembling the whole thing by yourself?

Here are 3 reasons why you might want to consider taking the plunge:

1. You can create a custom machine that exactly matches your needs.
2. It will be much easier to upgrade your machine in the future because you will understand it completely.
3. You may be able to save a lot of money.

And, if you have never done it before in your live, you will definitely learn a lot about computers.
­In this article, we'll take you through the entire process of building a computer. You'll learn how to choose the parts you will use, how to buy them and how to put them all together. When you're done, you will have exactly the machine that you need. Let's get started.

The first step in building a computer is deciding what type of machine you want to build. Do you want a really inexpensive computer for the kids to use? A small, quiet machine to use as a media computer in the living room? A high-end gaming computer? Or maybe you need a powerful machine with a lot of disk space for video editing. The possibilities are endless, and the type of machine you want to build will control many of the decisions you make down the line. Therefore, it is important to know exactly what you want the machine to accomplish from the start.­

­Let's imagine that you want to build a powerful video editing computer. You want it to have a dual-core CPU, lots of RAM and a terabyte of disk space. You also want to have FireWire connectors on the motherboard. These requirements are going to cause you to look for a motherboard that supports:

• Latest multi core processor (either Intel or AMD)
• At least 4GB of high-speed RAM
• Four (or more) SATA hard drives
• FireWire connections (possibly in both the front and back of the case)

­Then it all needs to go in a case with enough space to hold multiple hard disks and enough air ­flow to keep everything cool.
With any computer you build, knowing the type of machine you want to create can really help with decision-making.

Refurbished laptop

Now people begin to start searching for cheaper options as they are having a low budget, under which they want something more reliable and durable. So the maker started to make an strategy in which they offer off-leased computers and laptops on cheap prices which are in range of a budget oriented buyer.

Some of the people has started to think that these off-leased/refurbished systems which laptop maker are giving on low prices are faulty ones, and they just want to increase their market share that's why they are giving out these low priced laptops or systems.
Well perceptions can be changed too, by giving them more authenticated information and good quality products in low prices. Refurbished systems are checked by the manufacturing company because if they sell out a faulty PC then it's a matter of their reputation and they might have to face some legal challenges, so they make sure that what they are offering in refurbished condition should be thoroughly checked and tested so that customer who buys these systems and laptops should not face any kind of problems.
Cheap computers does not always means that they are cheap so they won't be good, cheap computers are cheap because they are used ones, but they sometime comes with very good specifications too which can easily get a client what they are looking for. In the end Refurbished Computers or Cheap Computers are a good option for all people who want to use a computer by investing low amount of bucks.
Student who have tense budget, you can have a fastidious Refurbished hp desktop computer for your academy work without contravention your budget.
Those who have an undersized business this is a good means to make available all workers with an upright laptop or computer and save on your corporation everyday expenditure.
Parents with young children need to have a computer so you can make stay them away of mom and dad's computer then find them a reasonably priced Refurbished hp desktop computer!
Designers, architects who run mostly heavy design software can also use Refurbished hp desktop computers for their and client presentations. Officially Refurbished hp desktop computers can provide heavy data storage if you get huge hard disk.

Sony Vaio VPCY11S1E/S

Plenty of laptop maker deliver their own notebook computers in a variety of styles, although the Sony corp happens to be on this for longer as compared to most. You can certainly trace that all the way back again towards C Line around Feb 2007, which was swapped out with the CR Line within August that time and then the CS Series last year. However, while the outgoing CR was rather practical, the CS has been very a considerable step backward, therefore experts were not stunned to find out it quickly changed by the Sony Vaio VPCY11S1E/S laptop together with the advent of Windows 7.

There are 5 colors accessible: white, red, pink, blue and black. Any pink version no matter individual desire, is most likely the least likable preference of them all. Even consumers that like pink will see that the brighter, additional energetic shade viewed over the lid and hand rest does not sit properly using the somewhat sickly, pale shade applied on the rest in the laptop. No real issues may be made on the alternative options, even though, and we all especially prefer the red/black and white designs.

As for the general style, the VPCY11S1E/S isn't really a type icon, however it's yet another solid, incredibly properly set together laptop computer coming from Sony. While competitors tend to over complicate their models in an effort to stand out, Sony achieves to create a sense of type in a very far a lot more restrained approach. Every thing is within the correct place and posesses function, leaving your selection of coloration to make the statement - in the event that's what you're after.

Option isn't reduced only to colour, either. Even though we are reviewing one particular in the retail bound SKUs, which go for among £650 and £700 determined by where you shop, Sony provides modification possibilities via their web site. Options are not that varied, however it is possible to select fewer RAM, weaker graphics, reduced CPUs and a resulting £579 starting cost or perhaps advancements that consist of a 500GB hard disk and Blu-ray disk, delivering somewhat flexibility.

Connectivity is not too poor, either. Whilst the VPCY11S1E/S laptop doesn't have eSATA or USB 'sleep and charge' abilities, it does have got mini-FireWire - an increasingly hard to find terminal on laptop computers lately. Every thing else is fairly regular, such as: 3 USB ports (2x left, 1x right); High-definition multimedia interface along with VGA for video; a 34mm ExpressCard port, sound jacks (1x earphone, 1x mic); an Ethernet port on the back as well as separate memory card slots for Sony's proprietary types as well as the extra commonly utilized SD card format.

Yet another strength of this Sony Vaio VPCY11S1E/S is its display screen. Measuring 14.1in and when using the industry standard 1,366 x 768 native resolution it's not a masterpiece, it still experiences the comparatively shallow watching perspectives and glossy, reflective coatings of all notebook computers within this sector and value. But colours are just somewhat punchier, black levels a little bit deeper and whites a tad cleaner when compared with the normal, doing it greater in comparison with several we can come across.

Equivalent plaudits may be granted towards the accompanying touchpad. For starters it is large enough which the currently stylish multi-touch assistance is really helpful, unlike the recent Toshiba Satellite U500. The surface is actually completely clean, though the two buttons seem to be independently hinged thereby provide outstanding tactile response. If you are ever in doubt about precisely what you get if you ever spend a bit more on a brand just like Sony, this sort of finer details should really convince.

And what better way to enjoy such video clips compared to making use of your very own instant-on internet browser? It really is no Google Chrome OS, but pushing the 'Web' key above the laptop keyboard will take you from nothing to a internet page in about Twenty secs. This is really a really neat function that is well implemented.

iPad webcam Accesory from PhotoFast

The accessory is called the PhotoFast Webcam for iPad and it looks like any other webcam you would connect to a computer

Dell - Inspiron Laptop with Intel® Core™ i3 Processor - Cherry Red

Perfect gadget for PLC programing..

  What's Included

• Dell Inspiron Laptop with Intel® Core™ i3 Processor
• 6-cell lithium-ion battery
• AC power cable
• Software: Microsoft Works and more
• Owner's manual

Product Features

• Intel® Core™ i3-330M processor
  Features a 3MB cache and 2.13GHz processor speed.
• Intel® Core i3 processor
  Features smart 4-way processing performance for HD quality computing. Intel® HD Graphics provide extra graphics power for your laptop when you need it.
• 4GB DDR3 SDRAM
  For multitasking power, expandable to 8GB.
• Multiformat DVD±RW/CD-RW drive
  To create custom DVDs and CDs.
• 15.6" glossy WLED high-definition widescreen display
  With TrueLife technology showcases movies and games in stunning clarity.
• 320GB Serial ATA hard drive (5400 rpm)
  Offers spacious storage and fast read/write times.
• Intel® Graphics Media Accelerator HD
  For lush images. HDMI output for connecting to an HDTV. Built-in stereo speakers.
• Built-in 1.3MP webcam
  Makes it easy to chat with family and friends.
• 7-in-1 media reader
  Supports Secure Digital, Secure Digital High Capacity, MultiMediaCard, MultiMediaCard Plus, xD-Picture Card, Memory Stick and Memory Stick PRO formats.
• 3 high-speed USB 2.0 ports
  For fast digital video, audio and data transfer.
• Built-in Dell 1397 wireless LAN (802.11b/g)
  Wirelessly connect to the Internet.
• Built-in 10/100 Ethernet LAN
  For quick and easy wired Web connection.
• Weighs 5.4 lbs. and measures just 1.3" thin
  For easy portability.
• Long battery life
  Of up to 4 hours to give you more time away from an outlet.
• Microsoft Windows 7 Home Premium Edition 64-bit operating system preinstalled
  Provides a stable platform for word processing, Web navigation, gaming, media storage and more.
• Software package included
  With Microsoft Works and more.
• ENERGY STAR qualified
  Designed to use less energy and meets strict energy efficiency guidelines set by the Environmental Protection Agency and U.S. Department of Energy.
• Intel, Pentium, Celeron, Centrino, Core, Viiv, Intel Inside and the Intel Inside logo are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries.

iPhone 4

Slimmer, brighter, more powerful and apparently the product of 18 months development: the Apple iPhone 4 certainly is something. The wwdc 2010 opening keynote is over, and we’ve just been back to check out the new Apple smartphone. Set to debut on June 24th – and up for preorder from June 15th – the Jobs hyperbole and press shots don’t do the iPhone 4 justice in your hand. Whether you are an Apple fan or not, you have to give them credit for creating a very slick device

Sony VAIO P

Sony’s second-gen VAIO P ultraportable has finally shown up for preorder on the company’s US SonyStyle webstore, priced from $899.99 and with deliveries expected to kick off from around June 25th 2010. The newly refreshed VAIO P packs a 1.6GHz Intel Atom Z530 processor paired with GMA 500 graphics, and comes in five different casing colors

Electronics Basic Symbol (just for kids)

Here are five basic symbols that you will find on electronic wiring diagrams, along with a brief definition. Look them over. When you get to #12 you can see if you remember the name of each symbol.

• Battery--a DC (direct current) voltage energy source.

• Ground--the common or reference point in an electrical circuit.

                             

• Resistor--an electrical component that opposes current.

• Capacitor--an electrical device that can store an electrical charge.

• Diode--a one-way conductor that allows current to flow only in one direction.

   

CCTV camera

Network Camera STC-IPM3096A allows for round the clock surveillance in the "Day" / "night" in all light up 0.4/0.06 lux, and forms an image with resolution up to 1280 × 960 pixels.  It can be broadcast on the network simultaneously two customized stream video M-JPEG format and / or MPEG-4.

In addition, STC-IPM3096A has motion detector, equipped with 2 GB SD-card memory, alarm inputs / output, audio inputs / outputs for audio link between the operator and the area of observation and supports PoE. Setting up the camera can be carried out through a web browser or with the NetStation.IP-camera is capable of transmitting on the network to two video streams simultaneously in the MPEG-4 and / or M-JPEG with resolution settings and the framerate each. In the M-JPEG format with a maximum resolution of the image STC-IPM3096A can reach SXVGA (1280 × 960 pixels.) With frame rate 10-15 fps. Increase framerate flow up to 25 fps in this format by specifying the resolution VGA (640 × 480 pixels.) Or QVGA (320 × 240 pixels.).In MPEG-4 IP-megapixel camera capable of transmitting video VGA-standard full-frame mode Low, Middle, and High. To optimize the video stream in the M-JPEG for bandwidth video, you can choose the degree of video compression: Low, Middle or High.

Record and store video and audio c IP-camera can be carried out on a network video recorder (NVR), PC hard drive or external disk drives and arrays. For temporary storage of data, including anxiety, designed SD-card memory capacity of 2 GB, which is supplied STC-IPM3096A. This IP-megapixel camera can record video on a map constantly, cyclically updating archive as it is filled, or just disturbing video. Efficient operation IP-camera in the security video provided by the hardware motion detector, alarm inputs, which can connect an external alarm sensors, and alarm output, through which you can manage the work of executive device.  Built-in STC-IPM3096A VMD has the three levels of sensitivity and allows you to set up 48 areas of detection of 8x6 square grid elements. In the basic setup IP-camera "reacts" to the alarm event lasting no less than 100 milliseconds, but in order to avoid false positives during her reaction may be increased to 60 seconds. Thanks to the audio input / output cell 

STC-IPM3096A lets you listen to the zone of its installation or to arrange two-way audio with the operator of the security services.

Aircraft Receiver

The Passive Aircraft Receiver is basically an amplified "crystal radio" designed to receive nearby AM aircraft transmissions. The "passive" design uses no oscillators or other RF circuitry capable of interfering with aircraft communications so it should be fine inside the cabin of the aircraft. Nevertheless, check the regulations before using this receiver on a commercial airliner.

New security regulations probably prohibit this device on commercial flights. Do not expect to hear two-way aircraft transmissions with this receiver! It is a short-range receiver only.The detector diode is a 1N5711, HP2835 or similar Schottky detector diode. The 10 megohm resistors provide a small diode bias current for better detector efficiency. The tuning capacitor may be any small variable with a range from about 5 pF to about 15 or 20 pF. The 0.15 uH inductor may be a molded choke or a few turns wound with a small diameter. Experiment with the coil to get the desired tuning range. The aircraft frequencies are directly above the FM band so a proper inductor will tune FM stations with the capacitor set near maximum capacity. (The FM stations will sound distorted since they are being slope detected.) Other capacitor and inductor combinations may be selected to tune other bands if desired. (Try the CB band at 27 MHz.) The LM358 dual op-amp draws under 1 ma so the battery life is quite long. A speaker amplifier may be added to drive a speaker or low-z earphone. The antenna can be a couple of inches if the receiver is near the transmitter or a couple of feet for maximum range. The selectivity is reduce as the antenna length is increased so best performance is achieved with the shortest acceptable antenna. Try increasing the 1.8 pF capacitor value when using very short antennas and decreasing it for long antennas. The receiver could be built into a small plastic box with a short antenna inside.

Battery tipes

Basically there are two types of batteries; starting (cranking), and deep cycle (marine/golf cart).The starting battery (SLI starting lights ignition) is designed to deliver quick bursts of energy (such as starting engines) and have a greater plate count. The plates will also be thinner and have somewhat different material composition. The deep cycle battery has less instant energy but greater long-term energy delivery. Deep cycle batteries have thicker plates and can survive a number of discharge cycles. Starting batteries should not be used for deep cycle applications. The so-called Dual Purpose Battery is only a compromise between the 2 types of batteries.

Battery safety tips

Batteries is dangerous if we treat them wrong.We must think safety when we are working around and with batteries. Remove all jewelry. After all you don't want to melt your watchband while you are wearing the watch. The hydrogen gas that batteries make when charging is very explosive. I have had 2 batteries blow up and drench me in sulfuric acid. That is no fun. This is a good time to use those safety goggles that are hanging on the wall. Sulfuric Acid eats up clothing and you may want to select Polyester clothing to wear, as it is naturally acid resistant. I just wear junk clothes, after all Polyester is so out of style. When doing electrical work on vehicles it is best to disconnect the ground cable. Just remember you are messing with corrosive acid, explosive gases and 100's amps of electrical current.

Move it with a VFD - Part 2

As we saw last time, a VFD can often be used in a motion application where some high torque and variable speed is required. If we apply them properly they are one of the best motor controllers in industry. The key statement there is 'if we apply them properly'.

To apply one correctly we really need to understand the load requirements. Basically, we need to ensure we can supply enough current for the motor so it can produce as much 'torque' as needed.Torque may be a new term for you in the motor world. Generally, we talk about horsepower in the motor world but it relates to torque and that's what we need to discuss in the VFD world.

Torque is a force that produces rotation. It is commonly measured in units of lb-ft (pound-feet). It is the force necessary to cause an object to rotate... Think of a merry-go-round (carousel ride). To get it to rotate by hand you would need to push it with a certain amount of muscle. That 'certain amount of muscle' would be the 'torque'.

If you tighten a bolt with a small wrench it will be difficult. Use a bigger (i.e. longer) wrench and it will be easier to tighten. For example, to tighten the bolt to 50 lb-ft you would have to apply 50lbs of force to a 1ft long wrench. On the contrary, you would have to onlyapply 1lb of force to a 50ft long wrench to tighten it the same.

Many (most?) machinery loads are constant torque loads. Conveyors,compressors, etc are some good examples. Variable torque loads are generally most pumps and fans. A VFD is usually specified for variable torque loads because they can help save energy but they are used forconstant torque loads too.

Peak torque efficiency comes at a certain volts per hertz ratio. As long as our VFD stays at this ratio we can develop the rated torque.For example, let's assume we're using a 460 volt source at 60 hertz.The ratio is therefore:
volts / hertz
460v / 60hz
7.667 v/hz

As long as the ratio stays in the above proportion we can supply the rated torque. So, if the volts fall we'll need to decrease the frequency to maintain the same ratio.

Horsepower is torque with the addition of time and distance. So, it's the torque generated to move something a given distance in a given period of time. It's related to torque by the formula:

HP = (torque * speed) / 5252

For example, if we have 30 lb-ft of torque developed in a motor rotating at 1500rpm we get:

HP= (30 * 1500) / 5252
HP= 45,000 / 5252
HP= 8.57

For reference, if we exert 1 hp we can move 550 lbs in 1 second. If we are just holding the 550 lbs still, we are not exerting any horsepower.There MUST be movement...

No movement would mean no torque which would mean no horsepower. See?
To specify a VFD we need to understand the torque requirements of the load. We need to consider:
1- The torque required to start the motion
2- The torque required to bring the load to speed in a certain period of time
3- The torque required to keep the load moving
4- The torque required when the motor acts like a brake to slow down the load
5- And the peak torque needed by the load

Most folks will use an ammeter to measure the current under all the load conditions listed above and find the peak current drawn. The VFD is then sized to the motor based on the maximum current draw at the peak torque levels plus an extra margin. Notice that the VFD is not specified based on the horsepower ratings of the motor. It's a torque thing..

Move it with a VFD - Part 1

VFD is a Variable Frequency Drive. It works with AC motors and setsthem into motion. It does so by varying the frequency of the voltage
supplied to them. There you go. That's it. Simple... but now let's see
some details.

The VFD controls two factors of the motor... speed and torque. As you
may remember from your school days, torque is a rotational force and
speed is ... well... speed. Combine the 2 and you get into horsepower
but that's a topic for another issue.An induction motor (real commonly used by folks in the industrial
factories of the world) would rotate at a fixed speed that is
determined by the frequency of the voltage supplied to it.

Alternating current (i.e. AC)applied to the motor windings in the
'stator' produces a magnetic field that turns the motor shaft. We vary
the speed of the motor shaft by either changing:
1- The frequency of the AC applied to the windings
2- The number of magnetic poles in the windings

So, using a little math... and I mean a 'little math'... we can
calculate the speed of the motor. Just use the formula:
(120 * frequency) / number of poles = speed

If we supply a 50Hz voltage to a 4 pole motor and use the formula
above we can see that we will be turning the motor shaft:
(120 * frequency) / number of poles = speed
(120 * 50) / 4 = speed
(6000) / 4 = 1500rpm (Revolutions Per Minute)

So, if we examine the formula above a little closer, we can see
that if we want the motor to go faster we can increase the frequency
of the AC voltage applied to the windings. If, for example, we change
from 50Hz to 60Hz in the example above we get:

(120 * frequency) / number of poles = speed
(120 * 60) / 4 = speed
(7200) / 4 = 1800rpm (Revolutions Per Minute)

So, now instead of turning at 1500rpm we're flying at 1800rpm.

How else can we change the speed? Well as we read above we can also
change the number of poles our motor has. So, if for example our
motor had 8 poles in the original example we'd be moving at:
(120 * frequency) / number of poles = speed
(120 * 50) / 8 = speed
(6000) / 8 = 750rpm (Revolutions Per Minute)

So, now instead of turning at 1500rpm we're crawling at 750rpm.

Trouble is, however, that the poles are a physical 'fact' of the motor
so we can't just change them on the fly. We'd have to change the whole
motor! What good is that if we just want the speed to vary?
No good...

So, you can see that the best way for us to change the speed of the
motor is to 'vary the frequency' of the voltage being applied to it.
Can we do that? Sure we can... with a Variable Frequency Drive (VFD)!

Stay tuned as next time we'll see how the VFD actually works along
with it's relationship to our powerful friend 'torque'.

AS-Interface... Let the Sensors Do the Talking - Part 2

 

Let's continue with our AS-Interface discussion. You will remember from last time that we discussed the physical hardware features. we pointed out that up to 31 sub devices can be connected to 1 main device. maximum separation between them can be up to 100 meters...
that's a far distance, isn't it?

Regarding speed, it's 'reasonably' quick. Each device added to the network increases the time needed for communication. Each device requires a maximum of 150 us to talk. Plus the network needs 300 us to
do some housekeeping.
So, a network with the maximum 31 devices needs
(31 x 150) + 300 = 4650 + 300 = 4950 us or 4.95 ms

A network of only 15 devices would therefore require:
(15 x 150) + 300 = 2250 + 300 = 2550 us or 2.55 ms

As you can see from the above, less units mean a quicker speed. If we have 15 devices connected we can pretty much guarantee that they will be spoken to every 2.55 milliseconds. Not bad...

Now let's see what actually gets sent during each message transfer and  understand what goes on throughout the network.

Messages sent throughout the network are called telegrams. The main unit sends as many telegrams as there are connected and active sub devices on the network. So, if we have 25 devices connected the main
unit will send 25 telegrams.

Each sub unit will be sequentially polled by the telegrams from the main unit. The sub unit with the lowest address gets polled first and then the next higher, etc. If a sub unit becomes disconnected the main
unit will notice within 1 cycle time (a maximum of 5 ms).

An AS-Interface telegram sends/receives a message in both directions  with the sub units. First the main unit sends a request to the subs (a write command) and then the subs reply (a read command) all within a
single telegram.

So, we have a main call, then a main unit pause, then a sub unit reply and a sub unit pause.

A telegram will actually look like the below if we break it down into digestible pieces:

St Cb A4 A3 A2 A1 A0 I4 I3 I2 I1 I0 Pb Eb

St= Start Bit. This is always a 0. It's a 1 when not transmitting...

Cb= Control bit. This controls if we're working with 'data/parameter access' or 'command access'. It is set to 0 for data/parameter access and 1 for command access.

A4-A0= Address bits. This is the address of the sub unit we are talking with. There are 5 bits here because 11111 in binary is 31.
So we can talk to any of the sub units just by setting it's address here.

I3-I0= Information bits. This is the actual information that we are sending to the sub unit... depending upon the command.
Pb= Parity bit. this is used for error checking. If there are an even
number of 1's in the message this is a 0. if there are an odd number of 1's in the message this is a 1.

Eb= End bit. This terminates the message and is always a 1.

Now, let's put together a telegram where we are talking with only one  sub unit. It will look like the below string of data:

main unit call
St Cb A4 A3 A2 A1 A0 I4 I3 I2 I1 I0 Pb Eb
main unit pause
3 to 10 bit times
sub unit response
St I3 I2 I1 I0 Pb Eb
sub unit pause
1 bit time

Remember that the above communication happens in 1 telegram. If there were 25 sub units connected to the main unit it would still all be sent in only 1 telegram.

Well, hopefully we can see how easy this network is to understand. Not much to it when we break it down into pieces and analyze the results.

Transformer

Introduction to Transformers

Two coils that have mutual inductance make up a transformer. The coil connected to the source of energy is called primary coil and the other is called secondary coil. It is useful in that the electrical energy can be transferred from one circuit to another without direct connection. It can also change the voltage level from one level to another level depending on the windings ratio of the primary and secondary coils. It can only be used with AC voltage because no voltage is induced if there is no change in magnetic field.
The increase of the inductance of coils can be done by windings the coils on magnetic material like iron core.

Turns Ratio, Voltage and Current
In a varying magnetic field, the voltage induced in a coil is proportional to the number of turns in the coil. If the coils are wound in the same field, the induced voltages will be proportional to the number of turns in each coil.

Vs = Vp(Ns/Np) 

where

• Vs = secondary voltage 
• Vp = primary voltage 
•  Ns = number of turns on secondary 
•  Np = number of turns on primary

If no current is taken from the secondary(open circuit), the current that flows in the primary is called magnetizing current of the transformer. Typically, the transformer is designed in such a way that the power consumed by it is only to overcome the losses in the iron core and in the resistance of the wire with which the primary is wound.
If the secondary is connected to the load, the current on the primary is given in the formula below assuming that the entire primary current is caused by the secondary load.
Ip = Is(Ns/Np)
where Ip = primary current
Is = secondary current
Ns = number of turns on secondary
Np = number of turns on primary

Impedance Matching
 
Many devices need a specific value of of load resistance for optimum operation. The impedance of an actualload that is to dissipate the power may differ from this value, so a transformer is used to change the actual load into an impedance of the desired value. This is called impedance matching.
Np/Ns = Square root(Zp/Zs) where
Np = number of turns on primary
Ns = number of turns on secondary
Zp = primary impedance required
Zs = impedance load connected to the secondary

Example : A transistor for audio amplifier requires a load of 200 ohms for optimum operation and is to be connected to a loudspeaker with an impedance of 4 ohms. The turn ratio, Np/Ns required will be Square root (200/4) = 7.1 i.e. the primary must have 7.1 times as many turns as the secondary.


Construction of Transformer
 
Two common types of construction are SHELL type and CORE type. In the SHELL type both windings are placed on the inner leg, while in the CORE type the primary and secondary windings may be placed on separate legs. They are usually designed so that the magnetic path around the core is as short as possible.

The material used for the core is usually silicon steel, built up by laminations, insulated from each other by a layer of coating. The number of turns required is inversely proportional to the cross sectional area of the core. Typically, the windings of small power transformers usually have 6-8 turns/volt on a core of 1 square inch cross section and have a magnetic path of 10-12 inches in length. A longer path or smaller cross section requires more turns/volt and vice versa.

The material used for the core is usually silicon steel, built up by laminations, insulated from each other by a layer of coating. The number of turns required is inversely proportional to the cross sectional area of the core. Typically, the windings of small power transformers usually have 6-8 turns/volt on a core of 1 square inch cross section and have a magnetic path of 10-12 inches in length. A longer path or smaller cross section requires more turns/volt and vice versa. 

555 oscillator

This is the square wave oscillation circuit which used NE555. 555 was developed as the IC for the precision timer. It is compactness (DIP 8 pins) and it is simple composition. It is often used for the timer circuit, the oscillation circuit because of precision well the operation
 

NE555 is composed of the voltage comparators, the flip-flop and the transistor for the discharge. The composition is simple, but it is excellent one.
Three resistors are connected with the inside in series and the power supply voltage(Vcc) is divided in 3. This composition is an excellent point. 1/3 with power supply voltage is applied to the positive input terminal of the comparator (COMP1) and the voltage of 2/3 is applied to the negative terminal of the comparator (COMP2). When the voltage of the trigger terminal(TRIGGER) is less than 1/3 of the power supply voltage, the S terminal of the flip-flop(FF) becomes H level and an FF is set. When the voltage of the threshold terminal(THRESHOLD) is more than 2/3 of the power supply voltage, the R terminal of the FF becomes H level and an FF is reset.

The condition immediately after the turning on
 

Immediately after a power supply voltage is supplied, as for the FF, the Q becomes H and becomes L condition. Because is the L, TR is in the OFF condition and the electric current flows through the resistor of Ra and the Rb at the capacitor (C). Immediately after a power supply voltage is supplied, the electric charge isn't stagnant in capacitor(C). So the voltage of the X point starts from 0V. Because the X point is lower than V1 of COMP1, the S terminal of the FF becomes the H condition. With this, the Q becomes H, becomes L condition but they are in the condition already. On the other hand, because the COMP2 (+) terminal is lower than V2, the output of COMP2 becomes the L and the FF is stable in this condition.

Output's reverse (1)

When the voltage of the X point crosses V1 of COMP1, the output of COMP1 becomes L. However, this change doesn't change the condition of the FF. The output of COMP2 becomes the H condition when the voltage of the X point rises more and reaches V2 of COMP2. With this, the R terminal of the FF becomes H and the output state of the FF reverses. The Q becomes the L condition and becomes the H condition. At this time, OUT changes into the L from H. Because became the H condition, TR becomes the ON condition. Because the interface of Ra and the Rb becomes the grounded condition, the electric current which was flowing through C so far through Ra and the Rb gets not to flow through capacitor(C). The electric charge which was stagnant in capacitor(C) begins the discharge through the Rb and TR. Voltage of the X point begins to go down with this discharge. Because voltage of the X point goes down, the voltage of the COMP2 (+) terminal becomes less than V2 and the R terminal of the FF changes into the L condition from H. This change doesn't change the condition of the FF.
It is only in a little time that the R terminal of the FF becomes the H condition.


Output's reverse (2)


Because TR becomes ON, as for the electric charge of capacitor(C), it continues the discharge and the voltage of the X point falls. When the voltage of the X point becomes equal to or less than V1 of COMP1, the output of COMP1 becomes the H condition and the S terminal of the FF becomes the H condition. This changes the Q of the FF to H and changes into the L condition. Because became the L condition, TR becomes the OFF condition and the discharge from capacitor(C) stops. The electric current flows through Ra and the Rb again in capacitor(C) and the electric charge begins to store up. When the electric charge begins to store up in capacitor(C), voltage of the X point begins to go up and the output of COMP1 becomes the L condition immediately. After that, it repeats this operation and the signal of the square wave is output.

When charging (accumulating the electric charge) capacitor(C), the electric current flows through Ra and the Rb and in case of the discharge (missing the electric charge), it passes only the Rb. So, the time of the charging and the time of the discharge are different. By making the Rb compared with Ra big, the difference of both becomes small but can not make the same at all. To make the same, it is good if Ra is 0 ohm, but in the case, Vcc is directly connected with TR and TR has broken. Don't make Ra = 0 ohm absolutely. If doing the ratio of Ra and the Rb by several times, in case of the practical use, there is not a problem.

Timer IC ( 555 )

There are a lot of second sources in 555 because the circuit is simple and is with a good performance.
The second source is the IC to be selling by the similar function from the other manufacturer. The pin arrangement is the same and it is possible to replace.
There is an energy saving type of the CMOS, too



Resistor

As the resistor, I am using the type that the permission electric power is 1/8 W. More than 1/8-W resistor can be used, too. In the case, the size of the resistor becomes big. This time, 1/8-W resistors are used to make a circuit compactly.  







Capacitor

A multilayer ceramic capacitor is used for the capacitor to decide an oscillation frequency. The capacitor with good temperature characteristic should be used for this capacitor. The capacitor with good temperature characteristic is the capacitor where little change of the value occurs even if the ambient temperature changes. The polypropylene capacitor is a capacitor with good temperature characteristic. However, the precision of the oscillator doesn't become good even if only the temperature characteristic of the capacitor is excellent.




IC socket

The IC can be put to direct to the printed board, too. This time, a socket is used.








Calculation of the frequency of 555 oscillator


The oscillation frequency of this oscillator is fixed by the value of capacitor (C) and resistor (Ra) and resistor (Rb).
Roughly oscillation frequency can be calculated by the following formula.
Because there is an error of the part, the oscillation frequency of the actual circuit is sometimes different from the calculated value little.


Unit f : Hz / C : Farad / Ra and Rb : ohm

It is possible to calculate by the following formula in the time that the output becomes H level and the time which is made an L level.

The time that the output becomes H level (tH) The time that the output becomes L level (tL) The frequency (f)

---

It is as follows when calculating at the value of the circuit this time.

The time that the output becomes H level (tH) tH = 0.693 x ( Ra + Rb ) x C = 0.693 x ( 5.6 x 103 + 47 x 103 ) x 0.01 x 10-6 = 0.365 x 10-3 The time that the output becomes L level (tL) tL = 0.693 x Rb x C = 0.693 x 47 x 103 x 0.01 x 10-6 = 0.326 x 10-3 The frequency (f) f = 1 / ( tH+tL ) = 103 / ( 0.365 + 0.326 ) = 1.45 x 103 = 1.45 (kHz)

The oscillation frequency of the made circuit was to 1,114 Hz be with the +5V power. The difference with the calculated value seems to be the factor that the error of the part is big. I attempted to change 555 (different manufacturer) but the oscillation frequency was the same approximately.

---

I measured the change of the oscillation frequency by the change of the line voltage.


The oscillation frequency is stable at more than +3V voltage.
It is the most stable in the voltage for 7V to 9V and it is the change of about ±1Hz(±0.1%).