Wednesday, December 8, 2010

How to Work HandPhone

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How to Work HandPhone
1.3 Introduction

Before you go any further about
repairing mobile phones, of course, you must first understand the working principle of mobile phones in order to simplify the process of analysis of damage to the phone.

In this chapter will be discussed in broad outline and in general, because the development of mobile technology today is always changing.


Center 2.3 command processing input / output.


3.2.1 Command input.


Each time you make an order to the phone, for example typing an sms, play games, changing phone settings, voice recording, photos, and others. All of the above command is a command from the mobile phone users, which can pass the command-like device: keypad, camera, infra red, Bluetooth. All input commands will be accepted by the CPU, then the CPU will process all the input commands. CPU can process all the input commands based on system operating data contained in the IC flash. IC flash will store the input data when commanded by the CPU, RAM, while the IC will accept data from the CPU for a while.

3.2.1 Command Output.

CPU will provide overall command of the command input, the command from the CPU is very universal in the overall mobile phone navigation system, for example: giving the order to display graphical information on the LCD, giving orders to the UI (vibrator, buzzer, LED), gives orders to the power supply voltage to meretribusikan , and others.

3.3 Power Supply

3.3.1 Power up / down (On / Off)


The process to turn the phone is not the same as ordinary electronic circuits such as radio, etc. TV. At almost the same phone system with a computer, where the process does not turn on or turn off by disconnect power to the power supply. In the actual computer system if given the power, the system has functioned only in the inactive state, when in analogikan to humans
in a state of sleep, which the system will be ready whenever given the command to activate all systems. That's because when the phone has the battery then plug in battery voltage will go straight to the IC power supply, while at the same power supply IC will provide voltage to the processor. SW circuit On / Off cell phone you can see in the image of this diawah.

3.3.1 Distribution voltage

Circuits in cell phones there are many subsystems, which each sub-system has a voltage supply needs of different and at each voltage when the system will be given when necessary. Power given by the first mobile phone battery, the voltage from battrey will continue to power supply IC, the IC power supply voltage supplylah all will be provided depending on needs.

3.3.1 Battery Charging

Mobile phone battery charging process is very thorough at all, whereby the charging system will be computerized. Battery voltage will be in diteksi by the IC power supply and CPU, if the battery in a full state of the phone will reject the filling of the
transformer charger. This charging system is processed by charging IC.
3.4 Transmission of information data


Basically, a transmission system in communication systems, there are two systems, the reception (
receiver) that serves as reception of data or voice information, alphanumeric data and graphics from the base station to the mobile phone. While the transmitting (Tx) functions as a voice or data transmission information, alphanumeric data, graphics and network registration process
3.4.1 The registration process network

3.4.1.1 Initialization


The first time you make phone calls called by the initialization process. This occurs when you first activate your phone. You'll get a connection from the site terdekekat sell, then the cellular network will perform checks your account or membership is still active or not, then your calls will be processed further.

3.4.1.2 Inspection frequency list


Your phone will check the list of
frequencies on your SIM. Inspection covers carrie frequency flow quality, then look for Broadcash Control Channel or BCCH. Each BCCH will transmit a unique data markers, membedan between AMPS and GSM. In the AMPS system uses a dedicated radio frequency system in each cell, whereas on all GSM frequencies can carry information, but more important is the channel used to stream data rather than radio frequency
3.4.1.3 Identification of information


Base station or Broadcash Control Center will continue to deliver for the identification of information about the sell the site. The identity of the
wireless network is Carreier itself, then the area code location, and frequency yag used, as well as information about the surrounding cells. All information is used to determine whether your phone is active and in need of service. BCCH is not a radio frequency didedicated. BBCH will use the channel that will carry information in the form of bits at all frequencies within a cell.
3.4.1.4 Control Channel Control Inspection Broadcash


Cell phone radio frequencies will conduct examination bradcash control channel, where your phone will send a signal to review whether the signals are still within range. The phone will be like a radio scanning the entire list of BCCH frequencies one by one and check the signal reception. Measurements will be conducted at each level of the channel. Cell site will send a strong signal to your phone. Meanwhile in broadcash control channel is a mobile data stream from
the monitor did ase station called frequency control or frequency control channel burs burs (FCCB). Your mobile phone signals will synchronize with the system provider with wireless connection means. Once your phone has been communicating with the base station, then everything is ready for use.
3.4.2. Transmitting information data

3.4.2.1. signal processing of voice data, graphics, alphanumeric.

While mobile phone users are communicating, then the sound wave signal generated by mobile users will travel through the air. Gelobang voice signal will be received by the microphone to be converted into electromagnetic waves. And will proceed to the audio processor to be strengthened and processed.


If mobile phone users to sms, then type the command on the keyboard by mobile phone users will be processed by the CPU (Central Proccesor Unit)

3.4.2.2. changes in the digital signal into an analog signal (D / A converter).


In this section the data signal information is converted into an analog signal form. Because the RF section is still using an analog signal is shaped in part while the main processor in the form of a digital character. This needs to be an adjustment between two different characters that can be interconnected.


Furthermore, the data signal information already in will continue to convert the RF section.


3.4.2.3. Mixing the data signal with the carrier signal.


Information data signal will be sent to the base station, surely there must be a data signal carrying the information. Therefore, the information data signal will be mixed with the carrier by the RF signal processor. Carrier signal on GSM technology has a 900-1900 MHz frequency range, these waves are initially generated by the VCO, where the VCO will generate a wave of 3420-3840 MHz, which would then be in if the RF processor.


After the data signal information mixed with a carrier signal will then proceed to the section is called the modulation penguatan.sistem.

3.4.2.4. Strengthening end


Signal data information that has been mixed with the carrier signal will be received by the base station, while the distance to the mobile phone base stations far enough. Then the signal has to be really strong to be received by the base station. Then the signal must be reinforced by the PA Power Amplyfier. When strengthening the end of the delivery is not functioning properly then the phone will not be able to register network to the operator, this is caused because the base station can not receive the data signal information from mobile phones.

3.4.2.5. Distribution of Transmission lines


Once confirmed then the signal will be continued to the antenna switch for connecting to the antenna. Antenna switches can be in analogikan like airports, where in the data transmission of information in cell phones, there are two pathways, namely receiving and transmitting. So without the antenna switch on the received signal with the signal to be emitted will collide with each other, because there is only on GSM technology, there is one lane with a system called TDMA.

3.4.2.6. Transmitting to the base station


The next signal will be emitted through the antenna to the base station. Antenna will determine the outcome of the broadcast, then the signal is weak or strong depending on the quality antennanya.

3.4.3. Receipt of information data.

3.4.3.1. Receiving data from the base station


Signal emitted by the base station information to be received in advance by phone antennas. And then be forwarded on to the antenna switch for forwarded to the LNA.

3.4.3.2. Distribution of transmission lines


In order for transmitting signals do not collide with the signal reception, it will be first divided transmission signal by the antenna switch.


3.4.3.3. Strengthening early


So that the signal can be received well by the RF signals emitted by base stations will be strengthened first by the LNA (Low Noise Amplyfier). LNA not only functioned as a reinforcement, but can enable the cutting noise (sigh).


3.4.3.4. Separation of the carrier signal with the signal information


Signals generated by the LNA still mixed with a carrier signal, in order to be processed by the DSP (Digital Signal proccersor) then the data signal information must be separated first by the RF processor. This system is called the frequency.


3.4.3.5. changes in the analog signal into digital signal (D / A converter).


In this section the data signal information is converted into digital signal form. Because the RF section is still using an analog signal is shaped in part while the main processor in the form of a digital character. This needs to be an adjustment between two different characters that can be interconnected.


Furthermore, the data signal information already in the convert will be continued to the main processor (CPU). When the data signal is a voice tersubut information will be continued to the audio amplifier.


3.4.3.6. Strengthening the end of the voice signal


When the data signal information is voice data, it will be reinforced by an audio amplifier terlabih first before continuing to the speakers. Audio signal will be converted into electromagnetic waves, then needs to connect to the speakers so that the electromagnetic signals into sound signals which propagate in the air to be heard by people ears. 

              

The function of UEM, UPP, FLASH, RAM

 Knowledge The function of UEM, UPP, FLASH, RAM

UEM (Universal Energy Management)
UEM Description



UEM Inside there are several important roles as the Energy Management Cell Phone. Unlike Nokia DCT3, UEM is a combination of several ASICs such as: CCONT, COBBA, chaps and UI DRIVERS.

UEM stands for Universal Energy Management, in accordance with its name, UEM has some very complex functions, including:
Crystal oscillator (32 kHz)

Every phone system will be found oscilator small size which can generate pulses at 32KHz,. UEM that will provide the voltage and controlling this oscilator Crystal henceforth be forwarded to the UPP.
32 kHz RC oscillator Startup

While mobile phones in Power-down state, the RF Processor Clock can not be given to the UPP, the phone can power-up is needed for Logic System Clock to the UPP. Sleep is needed for this purpose produced by the Crystal Clock oscilator 32 kHz.
Real time clock logic

Clock, Date, Alarm Clock Logic required given by Cristal oscilator 32kHz.
Regulators Baseband & RF

UEM is given by the main battery voltage of 3.7 volts (VBATT). UEM has role as distributor voltage / regulator to all systems based on voltage needs to be required in every system.
Baseband Regulator:
§ vCore, for programming that requires voltage of about 1.0 - 1.8 Volt - 200mA to the UPP (vCore vCore DSP & MCU)
§ VANA, a voltage of 8.2 Volt - 80mA for the analog system function (Btemp, VCXO Temp)
§ FiO, giving mid 1.8 Volt - 150mA to Logic I / Os (Input / Output Logic: Level Shifter MMC, IR, IC Flash & SDRAM, Bluetooth, LCD,) and UEM Logic.
§ VFLASH1, provide the main voltage of 2.8 Volt - 70mA to IR, Bluetooth, LCD, LED drivers and voltage to the BSI.
§ VFLASH2/VAUX, a voltage of 2.8 Volt - 40mA for FM Radio and other Accesories.
§ VSIM, a voltage of 1.8 - 3.0 Volt - 25mA for SIM Cards

Regulator RF:
§ VR1, a voltage of 4.75 Volt - 10 mA to the VCP
§ VR2, a voltage of 2.78 Volts - 100 mA to: VRF_TX, MODOUTP_G_TX, MODOUTM_G_TX, MODOUTP_P_TX, MODOUTM_P_TX,
§ VR3, a voltage of 2.78 Volt - 20 mA to: VDIG, Clock Out VCTXO (OSC 26MHz)
§ VR4, a voltage of 2.78 Volt - 50 mA to: VRF_RX, VF_RX, VPAB_VLNA
§ VR5, a voltage of 2.78 Volt - 50 mA to VPLL, VLO, VPRE,
§ VR6, a voltage of 2.78 Volt - 50 mA to VRXBB
§ VR7, a voltage of 2.78 Volt - 45 mA to: VCO,
Charging functions

Cell Phone Battery charging process is controlled by the UEM. UEM has stored therein Charging Control that serves as the setting Battery charging process. The phone will automatically decide the current from the charger to Battery Battery voltage when the voltage has reached the maximum limit Charger although still connected to the phone, otherwise if the Battery voltage below the maximum voltage then the current from the charger will continue to be given to the Battery.
11-channel A / D converter (MCU controlled)

In the UEM stored 11Channels analog to digital converter used for bandgap reference and voltage reference, this section will measure the BSI, Btemp, Vcharge.
oBattery Voltage Measurement A / D Channel (Internal)
oCharger Voltage Measurement A / D Channel (Internal)
Current oCharger Measurement A / D Channel (external)
oBattery Temperature Measurement A / D Channel (external)
oBattery Size Measurement A / D Channel (external)
OLED Temperature measurement A / D Channel (external)
Interface FBUS and MBUS

FBUS & MBUS is used to transfer data from computer to phone, such as process (Flash Programming), File Manager, etc.. Those data will then be entered into the UPP and flash IC.
Security Logic (Watchdog)
Watchdog stored in UEM, first used for controlling the system power-on and power-down. Both are used to block the IMEI security and storage, Watchdog will control ROM IMEI in UEM IMEI is stored in the IC flash, if there is a difference between the IMEI in UEM IMEI and IMEI in Flash then the Watchdog will perform Power-Down within 32mS.
FLASH memory for code imei

Inside there UEM ROM used to store the IMEI data. IMEI data storage properties are OTP (One Time Programming) where the IMEI data can be written only once and can not be removed or replaced, therefore the former or never written UEM IMEI can not be used to other phones except when the IMEI is located in the IC Flash can be equated with the IMEI that is on UEM (Calulate Flash), this matter will be discussed in Chapters Software.
When the ROM was in this troubled or Corupt UEM UEM then this can not be used again and can not be repaired again, normally displays IMEI ????????? where the IMEI which is different from the UEM IMEI is supposed although there is only one number was different.
IR interface level shifters

Used to Infra red driver and the regulator, the data is subsequently forwarded to the UPP akn.
LED Interface, Buzzer and vibrator

Vibrator, Keyboad LED, LCD LED Driver UI Subsystem is controlled by residing within UEM. This driver commands to the UI provided by the UPP, UPP only give a very low voltage is required drivers to deliver enough current to the vibrator, Keyboad LED, LED LCD.
Audio codec

Earphone, Microphone, IHF Speaker, Handsfree can function as there are subsystems Audio Codec stored on UEM. This subsystem is used to modify the data signal digital information into audio signals, so that the audio signal can be heard by humans is needed strengthening (Audio Amplyfier) before forwarded to the speaker and microphone, the audio signal has a frequency of 20Hz to 20KHz.
SIM interface

SIM Card is the active component which has a microchip in it, each of which is the active component is required to supply voltage, the voltage provided by the UEM SIM Card from Baseband Regulator Subsystem 1.8 Volt - 3Volt, while the SIM Clock, Reset SIM, SIM I / O data provided through the Subsystem Interface, which has kept the SIM SIM Interface Detector, SIM and SIM IF IF Driver.
Serial control interface (Cbus & dbus Controled)

This section will control the interface using the data transmission between the UEM and UPP are implemented through CBUS and dbus to MCU Subsystem stored in the UPP.
Auxiliary A / D converted (DSP Controlled)

As a tool for konfersi analog signal into digital signal which is used for controlling DSP Subsystem stored in the UPP, this section will play a role in: Digital Speech Processing and the PDM coded audio.
RF interface converters

We have seen previously that the RF module has the character while Baseband analog signal has a digital character, so that both modules can be continuous with one another, or a translator is needed for a conversion to an analog signal into digital signal (A / D converter) and digital signal into an analog signal ( D / A converter). RF Interface Converter also called Multi Mode Converter which is a series of liaison between the RF module with UPP.


UPP (Universal Phone Processor)
UPP Description
Processor to the fourth generation Nokia (DCT4) using the UPP (Universal Phone Processor) as the center of all activities of computerization. Processor is the brain of the phone system that will work to coordinate all phone functions, including programmed instructions therein.

Nokia DCT4 technologies continue to evolve, WD2 and my heart is the development of technology DCT4. The difference is the type used Proccesor and internal memory capacity is large enough. UPP-WD2 and my heart can process data faster than the UPP DCT4, thereby facilitating features more sophisticated, such as the Symbian operating system, access the Class 10 GPRS (EDGE / BB4.5), Multi Task, TFT LCD, resolution until 2mega pixel camera, MMS, polyphonic ringtones to 48channel, MP3 player, Bluetooth, external memory (MMC Support), etc..



UPP Nokia DCT4, WD2 and my heart basically has the same structure, which distinguishes only specs: ARM, DSP Core (LEAD3) and stored in the cache RAM UPP, of course, the specification of ROM and RAM are stored in the UPP will be different from each other. UPP has several functions, including:
BRAIN

This section is the main brain of mobile microprocessor, this section has two functions:
MCU Subsystem
Subsystem MCU (Micro Controller Unit) is processed by the microprocessor ARM (Advanced RISC Machines) and supported by: MCU ROM, RAM Cache, DMA (Direct Memory Access) and Memory IF.
DSP Subsystem
DSP Subsystem (Digital Signal Processing) block is processed by the LEAD (Low Power DSP Enhanced Architecture) is used to process Digital Application (A-DSP) and Digital Cellular (C-DSP). This section shall govern the data traffic information on the overall system of mobile working.
Brain Peripherals
This section will connect all the commands from the MCU and DSP subsystem to the Body.

MCU and DSP subsystem performance is dependent once the cache RAM is stored in the UPP, Nokia WD2 and my heart has a large RAM cache, about 8-16Mbit. Cache RAM is a support unit. All orders are often used by the UPP will be stored temporarily in this section. With the Cache RAM, UPP no longer need to call the same command to other parts. Thus, the time required to perform important commands can be shortened, so that speed of execution will be better and faster.
BODY

All phones work the whole system is controlled by the microprocessor. Body is part of a microprocessor that functions as the executor of orders from the Brain. Body parts functioning as Digital Control Logic also like the following:
Function
Information
ACCIF

Interface for data transfer from accessories: eg from infrared and cable Fbus / Mbus which is connected to a computer to transfer data from phone to computer.
SIMIF

SIM Card Interface. The reading of data from such sim card SIM ID, storing the SMS and Phone Book, etc..
UIF

1. Interface audio signal to the earphone and microphone
2. As an interface LCD and Keyboard Interface
3. also used for camera Codec
Pup

Software used for data transfer to external MCU and DSP are stored in external memory (Flash IC) through a connection Fbus or Mbus. Suppose the phone in Flash, then the data from the computer that is connected to the phone Fbus Block pup will be received by mobile phone from the microprocessor and flash will be stored in the IC.
CTSI

This section is used for Clock Management for: PURX, clocking, timing, Sleep Clock, etc..
SCU

Control IF / RFbus to the RF Module. This section is used to control the frequency band which will be locked to the Base Station by RF Module (PLL).
MFI, GPRS CIP, RXModem

These three blocks together is used to receive and give information to the RF data module, but previously required konfersi D / A - A / D. This section also determines the speed of data transfer, eg for access or GPRS can also be used as a modem.

UPP can work if you have been given the voltage of 1.5V which is given by the Regulator and vCore voltage Logic (FiO) 1.8 volt dibeikan by UEM. At initial boot process, UPP requires registration 32KHz Clock (Sleep Mode), while the main Clock provided by VCTCXO from RF Processor for 13MHz.
Memories (Flash & RAM)
Memories (Flash & RAM)
UPP will not be able to function fully when not assisted by the memory. As discussed previously that the UPP has MCU and DSP subsystem therein. However, the subsystem can not keep the OS (Operating System) intact, due to very limited storage data, then the extra memory needed to store the MCU and DSP Software (Firmware). Memory required by the UPP is: Flash Memory, EEPROM, RAM.

On your Nokia DCT4, Flash Memory and RAM are combined one IC, referred to as "IC Combo Flash".

Flash Memory
Flash Memory is used for data storage software MCU (Micro Controlled Units) and software DSP (Digital Signal Processor) which is an OS (Operating System) on the phone, usually called (loosely), the Flash Memory be instrumental in whether or not a phone system. Language packs or language preference (on a Nokia mobile phone called the PPM), which is stored in Flash Memory, the phone that do not have a choice of Indonesian can be added or upgraded (Re-Flash) using tools and special programs.

These data not only data stored on the operating system alone, there are also pack the data content or User Data Area is used for storing data or programs by mobile users, including: Phone Book, SMS, Games, Applications, Wallpapers, Ringtones, Images , Movie, Etc.. Flash Memory in this sector can be removed with a manual from the cell phone.

Nokia DCT4 been emulated EEPROM with Flash IC. EEPROM is used for storing important data that have been set by the phone manufacturer itself, the data contained in the EEPROM are: Signal Value tunning, IMEI / ISN, SID, MIN, SP-Lock, Security Code, etc.. Therefore, when the phone is replaced IC flashnya will require the calculation of the IMEI code, if not then the phone will not work.

Nokia DCT4 average have data on the Flash memory capacity from 16Mbit to 64Mbit. While Flash Memory on Nokia WD2 will require data storage capacity is very large, ranging from 128Mbit to 256Mbit, therefore Nokia WD2 will have two to four fruits Flash IC inside.


Flash Memory on Nokia phones that use the processor in my heart, used two separate IC Flash: First, NOR Flash, used to store primary data, this is where the MCU and Security Software IMEI is stored. Both NAND Flash, mostly used to store user data, such as: Sounds, Games, Applications, and also which stores the language packs.

RAM (Random Access Memory)
As a temporary data storage is required RAM, Nokia DCT4 still use SRAM (Synchronous RAM) with a capacity of about 64Mbit who has been in intergrasikan with IC Flash (Flash Combo), while for the Nokia WD2 and my heart to use SDRAM (Synchronous Dynamic RAM) that have a data capacity of 128-256Mbit separately from the Flash IC.SRAM or SDRAM given supply voltage by the UEM through FiO 1.8 Vol        

Ohm's Law

 What is Ohm's Law?

Ohm's Law is made from 3 mathematical equations that shows the relationship between electric voltage, current and resistance.

What is voltage? An anology would be a huge water tank filled with thousands of gallons of water high on a hill.
The difference between the pressure of water in the tank and the water that comes out of a pipe connected at the bottom leading to a faucet is determined by the size of the pipe and the size of the outlet of the faucet. This difference of pressure between the two can be thought of as potential Voltage.

What is current? An analogy would be the amount of flow determined by the pressure (voltage) of the water thru the pipes leading to a faucet. The term current refers to the quantity, volume or intensity of electrical flow, as opposed to voltage, which refers to the force or "pressure" causing the current flow.

What is resistance? An analogy would be the size of the water pipes and the size of the faucet. The larger the pipe and the faucet (less resistance), the more water that comes out! The smaller the pipe and faucet, (more resistance), the less water that comes out! This can be thought of as resistance to the flow of the water current.
All three of these: voltage, current and resistance directly interact in Ohm's law.
Change any two of them and you effect the third.

Info: Ohm's Law was named after Bavarian mathematician and physicist Georg Ohm.

Ohm's Law can be stated as mathematical equations, all derived from the
same principle.
In the following equations,
V is voltage measured in volts (the size of the water tank),

I is current measured in amperes (related to the pressure (Voltage) of water thru the pipes and faucet) and

R is resistance measured in ohms as related to the size of the pipes and faucet:

V = I x R (Voltage = Current multiplied by Resistance)

R = V / I (Resistance = Voltage divided by Current)

I = V / R (Current = Voltage Divided by Resistance)

Knowing any two of the values of a circuit, one can determine (calculate) the third, using Ohm's Law.

For example, to find the Voltage in a circuit:

If the circuit has a current of 2 amperes, and a resistance of 1 ohm, (< these are the two "knowns"), then according to Ohms Law and the formulas above, voltage equals current multiplied by resistance:

(V = 2 amperes x 1 ohm = 2 volts).

To find the current in the same circuit above assuming we did not know it but we know the voltage and resistance:
I = 2 volts divided by the resistance 1 ohm = 2 amperes.

In this third example we know the current (2 amperes) and the voltage (2 volts)....what is the resistance?
Substituting the formula:
R = Volts divided by the current (2 volts divided by 2 amperes = 1 ohm

Sometimes it's very helpful to associate these formulas Visually. The Ohms Law "wheels" and graphics below can be a very useful tool to jog your memory and help you to understand their relationship.


The wheel above is divided into three sections:

Volts V (on top of the dividing line)
Amps (amperes) I (lower left below the dividing line)
Resistance R (lower right below the dividing line)
X represents the (multiply by sign)
Memorize this wheel

To use, just cover the unknown quantity you need with your minds eye and what is left is the formula to find the unknown.

Example:

To find the current of a circuit (I), just cover the I or Amps section in your mines eye and what remains is the V volts above the dividing line and the R ohms (resistance) below it. Now substitute the known values. Just divided the known volts by the known resistance.
Your answer will be the current in the circuit.
The same procedure is used to find the volts or resistance of a circuit!

Here is another example:

You know the current and the resistance in a circuit but you want to find out the voltage.

Just cover the voltage section with your minds eye...what's left is the I X R sections. Just multiply the I value times the R value to get your answer! Practice with the wheel and you'll be surprised at how well it works to help you remember the formulas without trying!

This Ohm's Law Triangle graphic is also helpful to learn the formulas.
Just cover the unknown value and follow the graphic as in the yellow wheel examples above.

You'll have to insert the X between the I and R in the graphic and imagine the horizontal divide line but the principal is just the same.


In the above Ohm's law wheel you'll notice that is has an added section (P) for Power and the letter E* has been used instead of the letter V for voltage.
This wheel is used in the exact same fashion as the other wheels and graphics above.
You will also notice in the blue/green areas there are only two known values with the unknown value in the yellow sections. The red bars separate the four units of interest.

An example of the use of this wheel is:
Let's say that you know the power and the current in a circuit and want to know the voltage.
Find your unknown value in the yellow areas (V or E* in this wheel) and just look outward and pick the values that you do know. These would be the P and the I. Substitute your values in the formula, (P divided by I) do the math and you have your answer!

Info: Typically, Ohm's Law is only applied to DC circuits and not AC circuits.
* The letter "E" is sometimes used in representations of Ohm's Law for voltage instead of the "V" as in the wheel above. 

 

How to measure voltage direct current (DC)

 How to measure voltage direct current (DC)

Suppose we will measure the amount of voltage that exist in our homes. Nets voltage electricity in the homes are generally 220 volts AC. What we are measuring the voltage that existed at the Stop-Contacts. Note the scale list AC / DC on the meter. At the top: 0 2 4 6 8 10 In the center: 0 10 20 30 40 50 On the bottom: 0 50 100 150 200 250 Note also the limit on the Switches voters ACV measurements. 10V - 50V - 250 - 1000 V. measurement mode.
Because that would be measured is the voltage 220V PLN nets, then turn the selector switch to the position on the range of measurements 250V ACV at the top. It should be noted that the range of measurements must be greater than the voltage to be measured so that meter is not damaged or burnt.
Then Test Probe (cable pencolok) red (+) input into one of our Stop-hole probe, input contacts and black (-) into the other hole. Because the AC voltage dikur then turned to enter the probe if there will be no problem.
Now we look at the list Meter Scale, when the pointer moves and shows the scale of 40 on the bottom, so that the measuring voltage is 200 volts AC. And if in case the needle guide points to limit the scale 20 on the bottom so that the measuring voltage is 100VAC.

How to measure voltage direct current (DC)

To note the list of DC voltage mengukr Scale AC / DCV. At the top: 0 1 2 3 4 5 In the center: 0 5 10 15 20 20 On the bottom: 0 20 40 60 80 100 Note also limit DCV Measurement 25 50 250 For example we will measure the DC voltage from a battery. The trick is as follows:
Because the measured voltage 12 volts, then turn the selector switch positions red Kea DCV measurements on the boundary under the OLT 25. Range of measurements must be greater than a measured voltage to meter is not damaged.
Connect the red probe (+) to the positive pole (+) from battery and the black probe tip (-) to the negative pole (-) from battery. In order to note the position of the positive pole (+) and negative pole (-) battery should not be reversed.
Now we watch list Meter Scale, the needle will move and stop at the boundary between the scale of 10 to 15 (+ - 12V) at the bottom.

Then the voltage measured quantities are: When if the needle stops at the boundary scale 10 in the middle, then the battery voltage is: With a 10-volt voltage means the battery is already weak and need to discharge or in the contents again.

How to measure the resistance (resistivity) of components
In principle, measure the resistance (resistivity) component is to measure the amount of current flowing in these components, the smaller the resistance the greater the current flowing in parts, but if the resistance is high then the smaller the current flowing to the component. So it is necessary for current sources. Please note that in AVO meters themselves have a current source derived from a battery so that when measuring the resistance component current will flow. To measure the prisoners need to be considered a list of Ohm Meter Scale top. Limit Meter scale is: 0-5 - 10 - 20-20 -3 00-40 - 50 - 60-70 - 100-100 -100 - 200 - 1K-5K - 1M to infinity (~). Range of measurements: X 1 - X 10 - X 1K - 10K X. If it is not yet known if the value detainees, a position selector switch should always start at the X 1, if it turns out the needle moves only slightly rotate positions X 10 and if you still move a little play again at the position X 1K. To be accurate in his assessment needle pointer, then you have to calibrate the meter (Ohm Ajusment), which set the scale pointer to position 0 Ohm Ajuster by turning red direction left or right so that the needle right on the numbers 0 indicator. Ajusment Ohm activities must be done each time will measure the resistance (resistivity).

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