Thursday, September 26, 2013

UPS All You Need To Know

Good afternoon everyone. Sometimes I hear people ask about UPS, it's back-up time, ratings and more questions like this. So, I'm trying to write about these stuffs. This will be a bit basic stuff. If you are into tech stuffs you might know more than this. Still hope you will enjoy reading.

UPS What is this?

UPS stands for Uninterruptible Power Supply. Your personal computer or maybe laptop or other similar electrical equipment runs from AC outlet of your home. AC power that is provided by this outlet is not stable, it may vary by small amount with load and sometimes there might be power outage. That is load-shedding or something like that, maybe a cable fault. If you are in the middle of an important work and suddenly your computer just turns off, you will loose important data or think about medical equipments that needs to be on 24/7. So, you will need an UPS to get backup to save your important data or keep life saving equipments running in power outage situation. As soon as electricity fails UPS turns on and keep your system running thus giving you the opportunity to save the important data before turning off the computer.

It has batteries inside which charges from the AC main line and with in the event of a power outage these batteries supply that necessary power.



How Does It Work?



Let's start with offline UPS(Later I have explained both of them).

UPS takes in AC power from AC outlet and simultaneously 1. Provide AC power to the output, and 2. convert it(from main's AC) to DC to charge single or multiple Lead Acid Battery and when power fails an inverter turns on taking power from the battery and provide sine wave to the output. As soon as the battery is dead UPS stop providing backup. It charges from the AC mains again when AC power comes back.


Offline UPS




This is a very basic block diagram of how UPS works. Here Red lines indicates the AC line, Blue is the DC line, and the Green is the control. As you can see it takes in AC power straight to the Transfer Switches and to the battery charger. Transfer switches are actually relay based switches. Battery charger converts AC to suitable DC levels and charges the battery. Control always monitors battery level and if battery is fully charged it sends signal to battery charger to turn of charging. When AC is on control keeps the AC flowing to the output but as soon as AC fails control sends signal to turn on the Inverter and the Inverter takes in DC power and gives off AC power. Relay switches between direct main line connector and Inverter. Thus keeping the load turned on. The whole thing happens within very small amount of time that computer doesn't turn off.

In real world things might be a bit more complex but the main working principles stays the same. An offline UPS might use the same transformer as both inverter and step down transformer for charging the battery.

Rating, No watt?

You might have noticed that UPS comes with a volt-ampere rating rather than a watt rating(which you will find in your power supply). Well we are talking about AC voltage here, In DC we just multiply voltage and current and we will get watt, but In AC there is one more term to worry about and that is power factor. Not going to get in depth of it just remember in AC Voltage*Current*Power Factor = Watt. So, if you have a 1200VA UPS with 0.6 and 0.8 power factor what will be the maximum capacity?

1200VA * 0.6 = 720W
1200VA * 0.8 = 960W

So, UPS with a higher power factor is needed here.

If you buy a 650VA UPS with a power factor of 0.6 and your system's consumption is 450W when loaded, assume you are playing Battlefield 3 or Crysis 3 which is causing the system to draw 450W power, if AC fails your computer will just turn off. It won't even give backup for even fraction of seconds. Because 650VA * 0.6 = 390W which is the UPS's capability and you are drawing 450W.  So, get an UPS with higher power factor and calculate the amount of load you are planning to put on it.


So, I get a higher VA Rating and will get higher backup?

Well, Yes and No.

UPS VA rating stands for its maximum capability not for backup time. Though higher VA usually results in longer backup time but backup time and VA is not connected that much.

Like I said earlier UPS has battery inside(or maybe outside) of it. Usually these are Sealed Lead Acid Type battery or lead acid type battery. 





650VA 800VA 1000VA UPS have one of these battery, where 1200VA 1500VA have two of these battery. So, 650VA-1000VA converts 12V to 220V and 1200VA or 1500VA converts 24V to 220V. 

Now let's look at the battery, it is a 8.2Ah 12V battery. What it means? It means if you pull 8.2Amp from this battery at 12V this battery will last for 1hour. 8.2A from 12V is 8.2*12 = 98.4W. So, If you run a 98.4W 12V load with this battery it will last for an hour.

If you pull 16.4Amp or 196.8W from this battery it will last for 30 min. And if you pull 4.1Amp that is around 50W it will run for 2 hours!

Wow my computer burns only 100W, so I will get 1 hour backup! 


Wait! You have heard half of the story!

Remember the construction, DC voltage enters into the Inverter, where it is converted to AC via Power Transistors and then fed into a Transformer to step it up to a higher voltage level like 110V/220V. This conversion method is not efficient, a lot of heat generates thus a lot of energy wastes, moreover transformers have losses, different kind of losses, so there's another power loss there. And last but not the least your system's power supply is not 100% efficient either. Maybe 60%-90% efficient. So, your system's power supply will draw more power than its providing.

So, a lot of losses decreases the backup time! Yet try to get a UPS that has higher AMP-HOUR rated battery.


 
Now, why multiple battery?

Multiple battery are connected in series. Hope you know what will happen if you connect it in series. Two 12V battery result in 24V. Assume two 12V 8.2Ah battery. So, total 24V 8.2Ah battery(In series current stays the same) so, now you can run 196.8W load for an hour! 


So, you see more battery more backup. It is not necessary to be with a higher VA rating. Later I will tell a bit more about it.

Although you can't just put multiple battery anywhere, the circuit has to be capable of working at that voltage.

 
How fast?

UPS has a very fast switching speed. It can switch between AC main line and Inverter within millisecond so that Computer won't turn off. Each computer power supply has a Hold up time. This is the amount of time Computer's power supply can provide power(from the bulk capacitors) to keep the system running even if the AC power is out. You will need a UPS which has a speed faster than this Hold up time. Within the hold up time if power fails and inverter start providing backup computer won't feel anything. But if, lets say the computer or any other device has a hold up time of 15ms and the UPS needs 18ms to provide power, computer or that device will simply turn off. Luckily most consumers UPS can provide power within 5ms.


 
Types of UPS

There are two major types of UPS available in the market. 

Offline UPS
Online UPS


 
Offline UPS:

 

Diagram that I have shown on top of this post is actually of an Offline UPS. In this type Inverter only turns on when AC fails. So, rest of the time AC supply will go directly to load or maybe via Automatic Voltage Regulator or Surge Protection System. But if these protections are not available surge might damage the load. But most modern UPS has these protections so don't worry. Offline UPS is the cheaper one and less reliable one. Although it is more efficient than the online counterparts.

 
Online UPS

In online UPS Inverter always stays on. So, there is no break. This type of UPS takes in AC voltage, step it down with a transformer then converts it to DC and use that DC to both Charge the battery and to feed the inverter circuitry. As soon as AC fails battery starts providing the voltage required for inverter. So, this circuit produces more heat than offline UPS. But as output is totally isolated from the input AC, the output power quality is higher. Different types of protective measures can be taken here. This units cost a bit more than offline one.


You might sometimes see that this type of UPS is marked as double conversion UPS, the reason is it actually has two conversion units running simultaneously. One converts the AC to DC and the other converts the DC to AC and drives the load. As the inverter has to always stay on the heat generation is also high. Moreover inverters are not that efficient so the overall efficiency of online UPS drops to 80-90%. 

Online UPS may employ power factor correction circuitry and frequency regulation circuit which makes the efficiency and quality of power a bit better.



Schematic Of An Online UPS

As you can see online UPS has a totally isolated output. It is a bit more reliable than offline UPS. Because of the isolation it is easier to suppress the AC noise and protect the load from ripple, transient voltage or surge and brownouts. Better protective measures like low voltage or high voltage protection and surge protection can be implemented easily.


Why Back Up Time Decreases Overtime?

As you might have already faced backup time decreases overtime. And with frequent using backup time decreases even more. That's because of the characteristics of sealed lead acid batteries being used in this devices. 





From the graph shown above its clear that if you use 100% of its capacity everytime you will only get about 200 cycles. This number will change from battery to battery but the thing is higher the discharge depth is lower the number of usable cycle is. 

If you use a battery everyday to 100% and fully charge it back again, it will only last around 200 days, not even a year. Now you can do your calculation.

If capacity drops significantly you can replace existing batteries with similar type of battery.

You can read this manual for more info.


Maintenance

1. Don't use it in a very hot place. As you can see from the graph below that with higher temperature service life reduces drastically.







 



2. Don't leave it discharged for long time. As it will damage the battery even more. Charge it regularly.


 As you can see with time the battery self discharge and looses its capacity if not charged after reaching 60% of its capacity.

3. Don't overload it. 

4. Keep it in a dry place.

5. Visually inspect for any mechanical failure or check for any smell that indicates burning of something.

6. Regularly clean it, you can use a blower to do that.
 

UPS HACK:

Assume you have a 1000VA single 12V battery UPS which has a power factor of 0.8. And the battery is dead. You want to replace it. You can replace it with a higher capacity battery even with a car battery for that matters. Say you had a 12V 9AHr battery earlier. You can easily replace that with a 12AHr battery which will increase the back up time slightly.

Connect battery with the proper polarity. Positive with positive and negative with negative. You can use a multimeter to determine the polarity. And batteries will usually comes with polarity marked on them. Another thing you can look up is, usually the black wire is the ground wire.

What if a car battery is used? Like a 12V 100AHr battery? well it will give back up but the charging will be a bit tricky. Lead acids battery needs to be charged at 1/10th of its current capacity. So if a UPS has 9/10AHr battery the charging circuit is providing only 1Amp of current. But a 100AHr car battery requires 10Amp of current to charge, charging it at 1Amp will need days to charge it properly.

One way to solve this problem is using a different charging circuit for the batteries, connecting with a relay based switch. The way it will work is when the AC power is available the load will run from the AC and the battery will be charged from a different charging circuit, as soon as the AC is gone the relays will shift their switches in such a manner that battery terminals get to contact with the UPS actual battery terminal thus providing back up.

I'm adding a small schematic to clear this up a bit.


UPS Hack

Only two items are needed, one a simple relay that is connected with the Charging circuit, battery and the battery terminal of the UPS. Relay's common terminal is connected to the battery and the normally connected terminal is connected to the battery terminal and the normally open is connected to the high current charging circuit. Relay can be powered directly from the AC main line via a step down transformer, AC to DC converter and voltage regulator. 

When the AC is available the load is being fed from the AC main line via the Transfer Switches, and that AC is keeping the relay On and the charging circuit On. The way the relay is connected if the AC power is On, the Common terminal will touch the Normally open terminal thus charging the battery. As soon as the power fails, relay's common terminal touches the normally connected terminal thus providing power to the UPS circuit and the inverter. So the load will keep on running. As relays are very fast we don't need to worry much about the load's hold up time.

Some smart UPS might not be happy with no battery on its battery terminal but some of them just work fine.

When powering up the relay make sure to use proper transformer. You want to select such a transformer that will provide such a voltage that won't be able to drive the relay at AC input 190V or lower.  

Warning:
High voltage application, be cautious.

 

Some more info:

AC to DC conversion.
Voltage Regulating.
How Relays Work.

Read my other posts here.

Have a nice day.

Wednesday, September 25, 2013

Stethoscope/Spy Bug Using Op-Amp

Welcome again. This post is about a hobby project of how to make a Stethoscope or a Spy bug using Operational Amplifier as known as Op-Amp.

I will write about Op-Amp later. But now will just talk about the project and how to build this.

When I was young(10 years from now) I came across Op-Amp for the first , the TL062. I had plan to make a piano or something, and found this chip very suitable for the job. For audio we can use other Op-Amps too.

For basic, Op-amp is such an amplifier which has a very high sensitivity and gain. If it gets a small amount of input voltage it can amplify it very largely. Well the amplification depends on its supply voltage too. If the gain is high enough and mathematically the output voltage is crossing the operating voltage, it will saturate and its output voltage will be same as its operating voltage.

Let's look at an Op-Amp.

Internal Diagram And Pin Configuration of LM 741, LM324 and TL072


What it does is takes input voltage and spites out output voltage which is actually a product of its gain and input voltage. So, it can easily amplify any signal.


To hear heartbeat or hear what people is saying all you need is a microphone, and a headphone to hear what the microphone is hearing. But the problem is  Output of a microphone is so small that you can't hear anything if you directly connect it to a headphone or speaker. So, we need an amplifier. And Op-Amp is a very nice choice here.

Let's look at the diagram.



In this diagram, we will need only one set of input and output. Here we will take the input from the microphone which is around 0.02V and we will need around 2V to power up the headphone. So we will need an amplifier with a gain around 100. so 0.02V*100=2V. Here gain for this circuit is 1+220K/2.2K=101. So, it will do. We need resistors with around 1% tolerance, 5% tolerance will do.

This Op-Amp is running in non-inverting mode.

First 9V supply and 5K resistor is for powering up the microphone, the next 0.1uF capacitor and 100K resistor is for Removing DC voltage, it's actually a High pass filter, it will filter out DC level and a good AC signal will enter the Op-Amp. Op-Amp needs 9V 0V -9V supply.

This circuit can be used to hear heartbeat or small noises.

Any way that is all. Just try it. You can use any other Op-Amp instead of LM324. Anyway happy experimenting!

Dual Power Supply

First time I encountered a dual power supply setup when I opened up a RC Monster Truck that could go both front and back. It roughly had a setup like the following image.

IMAGE!


UNDER CONSTRUCTION

Now if you are into hobby electronics projects and tech stuffs you may have come across the idea of dual power supply. You might have seen that Op-Amp requires Dual Power supply. In different power supply labels you may have seen powers like +12V, 0V, -12V or something like that. This post will help you to make one for yourself.

When I was a kid my brother got a remote controlled vehicle which can go back and forth. And as usual we opened it up and found an interesting motor feeding system. Though the vehicle was running from 4 AA size battery but only 3V was given to the motor, either from 2 of the battery or from the other 2. Thus achieving a different polarity causes it's direction to be different. It was about 11 years ago. Anyway don't want to bother you anymore with uninteresting history. Let's see the first figure.



This is how dual power supplies work. You can use any of these three points for getting different voltage level. 

From Battery

First, let's see how to make a dual power supply from battery. You can use any type of battery. For example you can use 4AA battery or 2 9V battery.



Very simple, right? Just connect both the battery in series. Now the center of the two cells will work as the Ground, and two other terminals will provide positive or negative supply.

Very simple but effective. If you use two 9 volt battery you will get 9V 0V -9V power supply. With that you can power up small op amp IC or maybe small motor that will go in both direction.


Dual Power Supply From Battery

 

From CT Transformer

Okay now let's see how to make a dual or negative power from a center tapped transformer.


Unregulated Dual power supply from CT Transformer


Regulated Dual Power Supply from CT Transformer




Voltage Testing


Voltage Testing

 
Diagram above is a diagram of Dual power supply capable of providing 15V-0V-15V. You can read my earlier posts to find out more about how this circuit is converting AC from DC, what is voltage regulation etc. Those posts may help you to understand this circuit better. Now for simplicity I will describe it in brief. First the transformer steps down the power to a lower level. Here it is 18V. And then the diode IN4007 converts it's to DC. Adjacent capacitors smoothen the power - Lowers the voltage ripple and noise. You have already got the dual power supply. But it's around 15V 0V -15V. And it's not regulated (1st diagram). To regulate it to 12V we will need one positive regulator and one negative regulator. 7812 is a positive regulator where 7912 is a negative regulator both 12V and 1A capable. At the Output side you will get +12V 0V -12V power(2nd diagram).



Actual picture doesn't have the regulator added to it, yet. If you add a regulator you will get a cleaner voltage, that means less noise and ripple. Open pictures to see them in high resolution. You will be able to see diode orientation and polarity from voltages from this. I needed three multimeter but I only have one working right now, two of my meters got busted. But still you can see that positive from one point and negative from another. If we use only positive and negative point, we would have seen around 44V here.

From ATX Power Supply

Now, I'm going to show one more way. Most of us have seen computer power supplies. Small but efficient and powerful. ATX power supplies provide both positive 12V and negative 12V.


A Corsair CX750 Unit, Colors refer to Wire color and respective voltage



 
Voltage of Blue Wire Respect With Ground/Black Wire
Voltage of Yellow Wire Respect With the Ground/Black Wire
This is how you can get dual power supply from your ATX power supply. Simple keep the power supply turned on. Click here to see how. Anyway as you can see form the ratings Blue Wire provides -12V, Yellow provides 12V and black provides 0V. As we can see from the same 0V respect we are getting 12V both positive and negative, we can obviously use it as dual power supply.


You can also check your own power supply to see the ratings. You will see the Yellow wire is for 12V, Black wire is for 0V and Blue wire is for -12V. You can use Yellow - Black - Blue configuration to get +12V 0V -12V supply. Though most power supplies -12V will provide only a small amount of current. But that should be okay for running most of the small ICs. If your power supplies cables are not color coded you can always use a multimeter to measure the voltages.

Anyways these are the three basic ways to get dual power supply. Hope it will help. Will update as soon as possible.

You can visit the index for more interesting posts.

Warning

1. If you use the CT transformer or ATX Power supply, Take proper caution from shock hazard.

2. Don't touch the circuit of a running ATX power supply.

Thursday, September 19, 2013

Computer Power Supply Buying Guide

Good Morning Everyone. Anyone interested in Computer Stuff knows about power supply. Still we often get confused about which power supply to buy for our system. So, I'm going to write a post about computer power supplies. 

What is a Power Supply?

We know desktop computers run from AC 110V/220V. But the internal components do not run on alternating current, neither run on such high voltage. Different computer component runs on different voltage level. For example, a 3.5inch hard drive requires both 5V and 12V DC supply. Now, How can I provide that voltage? Simple using an adapter. PC power supply is that adapter. It sits inside of your system and convert its input 110V/220V AC to different DC levels. Standard power supply has 3.3V, 5V, 12V, -12V, 5VStandby output leads. Sometimes they have color coding. 





This is a 850W power supply from corsair. You can see its large cooling fan and bundle of wires. Those wires power up different devices inside of a computer..

Though power supply does not directly improve your system's performance it still is a vital element of the computer. You will be needing a proper power supply for systems durability and reliability. If you don't have the right power supply unit, your system may turn off without notice, power supply might gets burnt. So, a right power supply is very important. 

Now few basics about the power supply.

Wattage


All the power supplies you will see, you will find a Wattage rating printed on it. In most cases this is the amount of total power it can provide. Some power supplies print their continuous power and some print peak power. Remember always go for the higher continuous power rated power supply unit. So, if a power supply has a continuous 500W supply and one with a 500W peak, obviously go for the 500W continuous. This rating is actually the combined output power of all the different voltages.



This is the rating of a Thermaltake Toughpower 1000W. Its printed on the side of the power supply unit. As you can see the 1000W is the combination of all the different voltages. 


Rails

When looking for power supplies you may have come across the word Rail, Single rail, dual rail, quad rail. It means the output leads. Like the 5V rail which provides 5V, 12V rail which provides 12V. But if it has Dual rail or Quad rail it means there are Dual and Quad 12V output port. In the above picture you can see there are multiple +12V. It means it has multi-rail.

For safety manufacturer divides the total 12V Output current in different 12V rail, each having a maximum amount of current limit. For example if a power supply has dual 12V rail each of them has 20A rating, that means this power supply can provide (20A+20A)*12V=480W in its 12V rail(Make sure to look for the combined total output power of 12V rails,some power supplies have low total output current, if a power supply has 20A rating on both of its 12V Rail but a 23A combined current rating,that means you can't pull more than 23A or 276W from its 12V rail). Anyway, right, 480W on its dual 12V rail, but what will happen if you hook up 300W on it, and somehow you hook up all the load on a single 12V rail. It won't run because it has a 20A current limit on its each 12V rail. That means each of the rails will provide 240W. If you want to use more than that you have to distribute the load on different rails. 

That's the reason I prefer single rail power supplies, it provides all the current on a single rail, so you don't have to worry about connecting the loads in right places. If you have a multi-rail power supply just don't hook up all the load on a single wire, use multiple wires to balance the load.


Most important Rail


+12V supply rail is the most important rail of a power supply unit. If you use a gaming system or heavy system look for the power supply with highest +12V current rating. If you plan on buying a lets say 550W power supply, you find two of them from different manufacturer one with 42A on its 12V rail, other has 44A on its 12V rail, buy the one with the 44A. Because all the heavy things on your computer depends on the 12V rail. Your computers motherboard will take in 12V supply via a 8pin or 4pin ATX connector and convert it to the appropriate voltage for Processor, RAM etc. If you use a mid to high end Graphics Card it will take in 12V via 6pin or 8pin PCI express power connector and convert it to proper voltage for GPU core and memory. Your optical drive or hard drive's motor spins using the 12V supply, cooling fans run on 12V supply. So, 12V is the most important thing, just buy a power supply which has a high +12V current.

Connectors 

Power supplies have different types of connectors for different device. 





In the picture above you can see the 20+4 pin main power connector, 4 pin and 8 pin processor power connector and 6pin PCI express power connector. If you look at the motherboard you will see there are two atleast two different points for plugging in the power supply unit cable. One of them is the 20/24 pin power connector, other is the 4/8pin CPU power connector. If you buy a motherboard that has 8pin CPU power connector make sure to get a Power Supply that has a 8 pin power connector. There are more connectors for Graphics card, Hard drive, Optical drive, Cooling fan etc. Graphics cards usually use 6pin/8pin power connectors, Make sure to buy a PSU with proper connectors for your system. Hard drives and Optical drives this days require SATA power connector(4/5pin) and cooling fans are often powered by Molex(4pin) connector.


MTBF
One of the important thing about power supply is the MTBF. It means Mean Time Between Failure. This is the approximate time that the Power Supply Will serve without any failure. Higher MTBF value means higher service hours. So, better taking a Power supply with high MTBF like 100000 Hours or more. Don't buy any power supply below 20 000 hours of MTBF. 


Remember power supply will only reach its MTBF if it runs at proper condition. You can't overload it, you can't run it in high temperature.

Efficiency 

Efficiency is also an important thing. Efficiency does not affect its output power but it affects its input power. Lets assume two power supplies with same power rating of 500W providing constant 200W to the load, one with a 60% efficiency and the other with a 85% efficiency. 

Then the one with 60% efficiency will  pull around 333W From AC input.
And the one with 85% efficiency will pull around 235W from AC input.

So,higher efficiency will surely cut your electric bill. For a greener world use power supply with high efficiency.

Cooling

Power Supply has transformer, DC to DC converter inside of it, which often get hot. To cool it down power supplies come with heatsink and fan inside of it. Some power supply has 8cm fan some has 12cm or even 14cm. Get a power supply which has a good cooling solution. The better the cooling fan is the better the heat dissipation will be. And it will result in longer power supply life.


Power Supplies with different sized fans.



Non-Modular/Semi-Modular/Fully Modular

You may have also heard these terms. It is the cable management feature. If you buy a normal non-modular power supply, All the cables will be attached with it, you can't remove them. So huge amount of cables will be lying inside of your system which can cause poor airflow inside of your case. Power supply cables blocks the airflow, more cables more blocking. Most of the time you won't be needing all the connectors but with the non-modular design you still will be needing to get them connected.

With the semi modular design only a few cables like the 4/8Pin power connector and 20/24pin connector is attached to it. It gives you the flexibility to use cables as you want. Use the cables that you need. Don't need to connect the other cables so, eventually it will be less jampack your system and will result in better airflow. This feature will also allow you to route cables as you want.

Fully modular has no cables connected (like the one in the above picture). You have to connect all the cables.


My choice is the semi-modular because we will need those cables no matter what. And each contact point may have electrical resistance, which  may lower the power. If you think about the resistance that might be present in connectors, Non modular will be best choice, but we need cable management for good airflow, so if we think about balancing it, Semi - Modular will be the best choice.


Support And Protection

If you plan on building a very high end system with multiple Graphics Card, you will need a certified power supply. The most common multi-GPU system is SLI or Crossfire make sure the power supply has these certificates. 

Good power supplies feature over current, over voltage, under voltage protections. These are very important feature. Accidental short circuit may blow up the power supply if it doesn't have over current protection feature. Moreover if accidentally load gets higher than its capability it will turn off automatically.


PFC

PFC stands for power factor correction. As this device will be running from AC, power factor is a very important thing here. In DC , watt is the product of voltage and current. But in AC watt is the product of voltage, current and power factor. So the better the power factor is better the power supply is. Modern good power supplies come with power factor correction mechanism. This mechanism automatically adjust the power factor to higher value. It results in lower power consumption. Efficiency and Power Factor is not the same, though they have almost the same effect.

So, that is all about power supply in brief.

Now lets take a look at which one to buy.

 1. Calculate your consumption. Find out how much power you will need. Get a power supply with atleast 20% higher wattage than your consumption. If you plan on overclocking buy even higher.

Remember your power supply will have the best efficiency when it will run on 50-60% load. So, if you have enough money you can buy such a power supply which has 200% rating of your consumption. It may require more money but eventually will pay off. More over lower load means lower temperature of the Power Supply Unit and lower noise from its cooling fan.

 2. My suggestion will be go for the single rail. 

 3. Study the power ratings carefully and buy the power supply with higher +12V current.

 4. Make sure the power supply has enough connectors for all your devices.

 5. Buy the one with Higher MTBF value.

 6. Buy the one with Higher Efficiency(must buy 80+) and better cooling option.

 7. My suggestion, semi-modular.

 8. Make sure to check for features like low voltage , over voltage and low current protection.

 9. Make sure it has Active PFC(Power Factor Correction)

10. Must have better warranty period.


11. Don't buy cheap or non-brand power supply. 


List of Good Power Supply Manufacturer


 1. Antec
 2. Silverstone
 3. Corsair
 4. Seasonic
 5. OCZ
 6. Rosewill
 7. Thermaltake
 8. Cooler Master
 9. Sapphire 
10. XFX

Hope it will help. That was all for now.

Tuesday, September 10, 2013

Newton-Raphson Method

Welcome everyone to my blog. Today I am going to write on Newton-Raphson method, which is in Numerical Analysis called the Newton's method widely in brief.

Newton-Raphson method is used widely in finding better approximation of roots of real-valued function. 

For doing this calculation we can take two easy ways, one with a graph that will help us through, or directly start calculating.

In the graphical method, all we need is to guess a point on the function f(x), draw its Tangent. Find out where it intersects x, again draw a new tangent using that intersecting point, we will get a new point on x. If it is closer to the function than the previous one, it is a better approximation. More iteration may result in even better approximation. Remember it may not work all the time.





Next one is the straight-forward calculating using calculator or something. In straight forward calculation, we need the formula. 




As you can see the formula is very simple.You have to make sure a few things though. 

1. f(x) must be equal to 0. That means it should be f(x)=0. If you have an equation like X^3 +2X=2, You have to change it to X^3+2X-2=0 this form.

2. Finding out f'(x) symbolically. According to the formula you have to find out the first derivative of the function that is given. You have to manually calculate this.

3. Choose an initial guess Xo, some people may call it X1 and the next one is X2 and so on, its totally up to you, you can write anything you want as long as you are writing the formula correctly.

4. Use formula to find out next value.

5. Now the next value will be the new guess, put it in the formula and get the next value.

6. You can keep on the iteration to find out better or closer results.

Absolute Relative Approximate Error 


Sometimes pre-specified tolerance is given, you have to use this approximate error to see how much error is in the calculation. To minimize error or get in the tolerance level more iterations might be needed.

Example 

1.

x^3 = 20, we have to find out a root of this function. 

First of all it needs to be converted to a form like this f(x)=0, so we can write x^3-20=0.

Now finding out the derivative. x^3 -20 will result in 3x^2.

Assume a guess of x=3.

Now putting that in theorem we get 

X1 = Xo -(f(Xo)/f'(Xo))

that is X1 = 3 - ((3^3-20)/(3*3^2))

X1 = 2.740740741

To find out X2, we will just replace the position of Xo with X1 and will get X2.

From there we can check what if the new result satisfies the condition or not. If not iteration will go on.

We can find approximate error if pre-specified error tolerance is given. We will just use the formula shown in earlier figure and will find out error. 

Using Calculator

If you want to speed up the calculation you can use a scientific calculator. Scientific calculators saves the last value as Ans. Just type the initial guess press = sign. Initial guess will be stored in Ans. Now use appropriate operators to establish the example 1. Now each time you press = it will show the next value, as Ans value changes with every click it will actually give you the results of onward iterations.


Any way that was all for now. Pretty basic stuff. Hope it will help.

Monday, September 9, 2013

MATLAB Basic Tutorial

Good morning everyone. Hope everyone is okay. Today I'm going to write about MATLAB, a very popular and handy application for doing a lot of works. It is a numerical computing environment.

So, lets dive in!

First of all how to get it. You can simply go to their site for downloading/buying it. Once you have done doing that, install it. And run it.

The interface will be like this.


In the picture you can see the MATLAB 2012b edition. It has File browser , Command window, Workspace, Command History from left to right. You will be writing codes in the command window area.

Let's start with the Basic Arithmetic Operators then.

Arithmetic Operators

1.   +   Addition

Simply add two or more digits by directly typing all the digits and pressing enter. Result can be directly stored in any variable 

12+23.5= 35.5000

d=1222+45, d=1267
[You can see the variable values in workspace]

2.   -   Subtraction

Simply subtract. Either it can be done directly by typing and hitting enter or can be stored in variable first and then apply operator.

23-5=18

b=23-5 , b=18 (stored in b variable)

3.   *   Multiplication

Same as before.

47*89= 4183

e=45*65, e=2925

4.   /   Right Division

Same as before.

5.   \   Left Division

Same as before.

6.   :   Colon 

This can be used for creating list.

list = -3 : 3 will result in a list from -3 to 3.
list = 1 : 2 : 20 will result in a list of odd numbers. This syntax means it will start from 1, with an increment of 2 it will end at 20.

7.   ^  Power

Same as before.

8.   '   Transpose

Check the wiki link I have added. It will give you a clear knowledge about Transpose.

a = [3 5 9]  will result in a Row vector of 3 5 9.
but a = [3 5 9]' will result in a column vector because of the Transpose Operator.


Let's look at the examples now.





Now, Let's do some Vector and Matrix Stuff!

1. Constructing Row Vector

a = [1 5 9 4 3 6]
Will result in a Row vector a with the following elements mentioned above.

Extracting a certain element-

a(3) = 9 
It will find the third element of a.

c = a(3)
Value of third element will be stored in c variable.

Change any certain element.

a(3)=8
Third element will be 8.

Deleting certain element.
a(5)=[]
it will delete the fifth element of the vector a.
[] is the empty matrix whose size is 0x0.



2. Constructing Column Vector

b = [5; 8; 7]
b = [5 8 7]' 
second line Transpose operator has been used.




3. Constructing Matrix.

A = [ 2 4 3 ; 5 2 9 ; 3 1 7]

Extracting elements from matrix.

A(3,2)
1

Results in A32 element.

Extracting Sub-Matrix

A( 1:2 , 2:3 )

Extracting Certain Row

A(3,:)
Here ":" means all elements in the array.

Appending.

Append a certain value to  the matrix.
Sizes of two arrays must be compatible otherwise will result in error.

Deleting certain Row or Column.

A( : , 3) = []
A( 2 , : ) = []

Note that earlier we have used A( 3,:) for extracting certain value.
Now we will be storing 0x0 in that location that is ultimately Zero.






4. Time for some Matrix Calculation.

Construct Matrices as shown earlier.

Assume they are A and B.

Using arithmetic operators like + - * we can compute A+B , A-B or A*B matrices.

Note :

1. ";" sign after a line will stop MATLAB to print on the command Window.


2. Anything written after "%" sign will be ignored.



Wednesday, September 4, 2013

Software List For Getting PC Details.

Welcome everyone to my blog. This post will be about a few software that can be easily used for getting in depth computer hardware information. You can use them for checking hardware specification and even monitoring temperature.


1. CPU-Z

This is a very handy software to get better information about Processor,Motherboard , RAM and GPU. Though this software is pretty much CPU information based.

Here how it looks.



This is the CPU tab of CPU-Z. In this tab you can see the Model Number, Codename, Maximum Thermal Design Power, Package Type, Fabrication Technology , Core Voltage(Changes with the Clock Speed), Family, Extended Family, Stepping, Revision, Supported Instruction Sets, Current Core Speed(It changes with the CPU Load), Amount of Cache Memory and Number of Physical Cores and Logical Cores(Threads).



The second tab shows few details about the Cache Memory of the Processor. Some AMD processors may not have Level 3 Cache.



The Next tab Mainboard provides Information about Motherboard, Bios and PCI Express.



The Memory tab provides Information about installed RAM, Its Type, Installed Size, Timing. Note that DRAM Frequency that it will show is not the effective frequency. As these are DDR(Double Data Rate) memory effective frequency will be doubled. So, here 668.7MHz*2=1337.4MHz. 



The next tab shows details about the installed RAM. You may select the RAM slot.



Graphics tab provide basic information about Graphics Card installed.

2. GPU-Z

This software  shows more detailed information about graphics card.



First tab contains information like Graphics Processor name, Codename, Fabrication Technology, Release date, Bios Information, Memory Size, DirectX support, Driver Version, Available Graphics Memory, GPU Clock, memory clock etc. If you use multiple graphics card you may select it from the drop down menu below.



The second tab which is Sensors tab provides information from the GPU sensor. It provides GPU current core clock, Memory Clock, Temperature, Load, Memory Usage, Fan speed etc. Information in this tab defers from GPU to GPU.


3. Open Hardware Monitor

This software provides details about Fan speed, Temperature, Hard Drives Temperature CPU and GPU load etc.



As you can see this software provides very good amount of details of the whole system, this can be real handy if you want to monitor your system's health and take proper measure to keep it that way.

4 Real Temp

Real Temp is one of  the lightest software for monitoring CPU core temperature. 


5.  MSI Afterburner

MSI Afterburner is a very simple and easy tool for monitoring Graphics Card. Don't worry it works with other vendors.





 With this tool you can overclock your graphics card. You can modify Power Limit, Core clock and Memory clock which is eventually overclocking, though don't do this if you really don't need it. You can also change the Fan Speed Curve and that will drive the GPU fan with higher speed keeping the card cool. You can lower the fan speed to achieve a quieter environment.

You can click on the settings and from there go to the Fan tab to modify fan curve. You can set the fan speed to auto or User Defined.



So, that was all for now. Hope it will help. Good day everyone.

Monday, September 2, 2013

More From USB

Good Morning and welcome back everyone. Hope you guys are doing fine. As the title says this post will be about USB port and another alternative use of this already very versatile and widely used port.

Let's talk a little about USB!

USB stands for Universal Serial Bus, its an Industry standard that defines cables,connectors and communication protocol used in a bus for connection, communication and supply power between computers and other electronic device or peripherals . In this day and age USB probably is the most used port in our day to day life as we charge our phones with it, connect numerous peripherals with computer with it and use many other devices that have this port which is really very convenient.

Like I was saying USB port not only communicate and connect but also provide power to the device and this power can be used for many other things too, all you have to know is which Pin is used for what purpose.


Voltage and current:

A typical USB ports have standard 5.0V and can vary slightly and the current might start from 350mA to couple Ampere depending on the source. Although modern USB power delivery can deliver up to 100W it is not directly achievable, you will be needing some more circuitry to get it even if your source supports it. So let's think about typical scenario and think about 5V 1A as the standard. Question is what can we do with this power. Well you can easily make a light for your keyboard if it doesn't have any back-lighting, you can run a small fan with it, how about powering couple of Infrared LED to give your laptop webcam some night vision capability! So as usual the possibility is infinite and you can pretty much do anything you want with this available power.


What to do?

You will need an USB Cable like this or any other type that can be connected with the host system for example your Laptop.





Now cut it in half. Well not exactly half more like according to your will. If you do so you will find 4 cables inside of it(If it is a USB2.0 cable).



To get the power we will only need the 5V Red wire as supply and the Black Ground wire as return path. We won't be needing the differential pair on this case. If there is no color coding you might want to use a continuity test to determine which one is which.




USB2.0 Pin configuration

USB3.0 Pin Configuration

An important note here, both USB2.0 and 3.0 has four common pins and they have the same alignment so you can get the power from either of them just fine.



An USB Powered LAMP


Now you can harvest the power from USB and do whatever you want with it.


Warning :
 
1. Do Not Short Circuit the power carrying wires. It might cause damage to the USB port.

2. Double check polarity before connecting.


So happy experimenting and have a good day.


Resource:

1. Wikipedia Page on USB.

2. My other blog posts.