What is Frequency Modulation FM. FM explained

FM or frequency modulation is a mean of modulating carrier with information or base signal in radio technology so that the RF or radio frequency can be propagated to distance receiver from a transmitter. There are three basic methods of modulation for radio frequency. They are CW or continuous wave, AM or amplitude modulation and FM or frequency modulation. CW or continuous wave was used in older days for Morse code transmission in the way that a fixed frequency and fixed amplitude signal wave was switched on and off and transmitted. this on and off signal was carrying Morse code information to the other side of receiver. In amplitude modulation a fixed frequency wave is used whose amplitude is varied according to the base frequency or information. Or in other words the base information is overlay of the carrier frequency signal. The next type is FM or frequency modulation in which the amplitude of the carrier signal is kept fixed and the base information is used to change the frequency of the carrier signal to take the information.

Different methods of modulation

The time of CW had passed. There in no more use of Morse anywhere. But still the amplitude modulation and frequency modulation is in use. Amplitude modulation are affected much from external disturbances where the FM or frequency modulation is affected very less. This is the reason we hear very clear ad beautiful music and voice at FM whereas at AM band this is not possible. The other reason for clarity is the frequency modulated signal provides much wider band for modulation of base signal or information which is up to 75Khz whereas the AM or amplitude modulation provides only 5Khz of bandwidth. Modren days FM or frequency modulation signal can even modulate stereo audio signal as base frequency which can be received by a stereo receiver are receiving end. Sure stereo audio signal is way better and natural compared to mono audio signal.

Frequency modulation can also use the concept of pre-emphasis and de-emphasis. In this system the FM signal is much more amplified at transmitting end and is then attenuated with the same ratio at receiving end. In this method the unwanted signals injection is also reduced and we receive a very clear signal at receiving end.

Modern days FM receivers are using one single chip IC which is responsible for doing all the required tasks and functions. Receivers are comparatively simple for FM. FM is using high frequency band and that frequency the need of the antenna is less. A small size antenna can effectively transmit and can receive the signal. One disadvantage of FM is the signal is highly direction or it uses line of sight. In normal conditions the transmission limit is 25Km circle for an FM signal.

Supper FM 9 radio receiver block diagram and features

 Here in this article you will see the block diagram and feature of a high quality FM radio receiver. FM radio receivers are very popular these days due to FM broadcast available all over. A good quality FM radio receiver is capable of producing quality audio which had been broadcast at the time of transmission. The receiver should be capable of receiving and producing stereo FM signal. This FM radio receiver is battery powered and is portable because it can be powered from a single 9V battery. A PP3 battery could do or a rechargeable battery could also work just fine. The power consumption of this radio is just moderate and battery could last for a few hours of listening. Dual power option is available if somewhere power line is available, the best choice to operate this radio could be the means power.

Supper FM 9 block diagram

This Supper FM 9 radio receiver circuit is based on superheterodyne function. In superheterodyne design the radio signal is amplified and is fed back again in the input several times. This way the signal become very strong and very large to be better identified by the audio frequency stage. The signal from the antenna is fed to the band bass filter. Then this signal is few to the tuned RF amplifier where the channel selection is made and a particular frequency band is selected to output. The band selection is made by a varicap diode whose capacitance can be varied by applying reverse biasing of the diode. Such diodes are very common in modern tuning circuits where a voltage signal is used to make the tuning. There are common in digital type tuning circuits.

Next is the mixer stage where the signal is mixed with the local frequency oscillator frequency to obtain the difference of the two frequencies which would be exact 10.7MHz. Then the signal is fed to the next stage 10.7MHz band pass filter where any other unwanted signals are rejected and the desired 10.7MHz signal is fed to the next stage the IF amplifier stage. In IF amplifier stage the signal is amplified. 

Next this signal is fed to the limiter and demodulator stage where the signal is seperated from the carrier. When the signal is separated from the carrier, the carrier is rejected and the only audio signal is few to the audio amplifier stage. Before sending the signal to the audio amplifier stage, the signal is fed to another stage the stereo signal detection where the signal is divided into two audio signals, L and R stereo signals. Then these L and R stereo signals are fed to two separate audio amplifiers where both L and R signals are amplifier to the the level so that two speakers could be driven by this audio signal.

TP4056 li-ion 3.7v battery 18650 Charging Module Detail, Pinout and datasheet

 In this text I will discuss about the famous TP4056 charging module which is a 3.70V  Li-ion battery 18650 in detail. The pinout, characteristics, setup and calibration for battery value will be covered in this text. TP4056 charger module is a very tiny size module to charge li ion batteries that it can fit anywhere inside any electronic equipment or instrument. TP4056 module consists of a single chip IC TP5640  and a few other supporting components which makes high quality and precision charging module which gives complete solution to automatically charge li-ion batteries of any small size. Using TP4056 module to charge the li-ion battery, it provides full battery life and effective charging to prolong battery life with great efficiency. Using TP4056 battery charging module you can make the line powered equipment less power consuming and the old equipment using dry cell can be converted to rechargeable battery solution.

TP4056 Charger or charging module

TP4056 Charging Module Characteristic and Technical details

1. Input mini usb, micro usb and C port as well as soldering pad connections
2. Two indication for charging status.
3. Over current and over charging protection
4. Battery charging current can be adjustable or can be controlled by replacing one resistor value to certain value which could be obtained easily from the table bellow in this text.
5. The module can connected to AC DC power supply by a usb type cable
6. Battery temperature measurement is made by IC. It will prevent during overheating.
7. Cheap in price and easily available everywhere
8. Softly starts charging. Soft start charging feature.
9. Automatic cut off charging when battery fully charged.
10. Battery full charge indication
11. Battery charging current can be adjusted from 130mA to 1000mA.
12. wide power supply voltage range form 5.0V to 10.1V DC.

TP4056 charger module explained

TP4056 charging module is a complete charging solution which provides efficient charging solution to 3.7V single rechargeable cell. This module can be used to charge any small size 3.7V lithium iron battery including 18650 cell. This charging module name employees TP4056 due to TP4056 chip used inside this module which is the main part of this module. A few external components are used to support the chip.

The IC has a temperature sensing pin where an NTC can be connected which would be placed on the battery and that NTC will stop charging when the battery under charge temperature will get increase. There are two led indicator sink type pins on the chip in which on of the LED shows the charging state and the other led turns on when charging is complete and charging is disconnected and the charged led would flesh.

TP4056 provides steady 1A charging current which could be reduced or programmed by replacing the value of one resistor.

Supper capacitor or suppercapacitor

 Energy storage device

Super cap

The supper capacitor or super cap is same like other electrolytic capacitors but they have a very big capacity to store large amount of charge. Most commonly used capacitors in audio amplifiers and stereos have values like 220UF, 500UF and 1000UF. UF stand for micro farads. In radio frequency circuits very small capacitance capacitors are used for example 10 pf or less. They are very small capacitors. In power supplies one can see large size capacitors like 1000UF to 10000UF to reduce the power supply ripple. There are hundreds and thousands of capacitors are used in any kind of electronic equipment. These capacitors have specific capacitance and voltage rating. Same is true for super cap. super cap have both capacity value as well as voltage value. The capacity is very very high for supper capacitor like in few hundred and even thousands Farads and the voltage rating is very low like 2.5 Volts for each super cap. Supper capacitor has quality that they can be charged very fast and they are capable of providing very large current peak. Also they don't tendency to degrade with passage of time like regular batteries.

Super cap or supercapacitor

Charging super cap

Super cap can be charged very quickly and they have ability to discharge very quickly too. They can be used as regular batteries with solar system, in electric vehicles, in torch lights and many other applications where batteries had used.

Super cap

Supper capacitors don't emit gas like lead acid batteries but they do store charge less than lead acid batteries. Supper capacitors can be used in series to increase the applied voltage or in parallel to increase the storage capacity. Hence strings of series are made and these strings are connected in parallel together to make reasonable battery having accepted voltage rating and charge store capability.

Super cap in series and parallel strings

Super cap charger

Supper capacitors could be charged using a DC to DC boost converter. But current limitation is a must for charging supper caps. Supper cap acts like a dead short if connected to a power supply for charging. It would cause to blow the power supply fuse or it would burn the power supply if the power supply have no over current protection.

TP4056 Lithium ion Lithium iron Battery Charge Controller

TP4056 is a Lithium iron rechargeable battery charge controller IC. The TP4056 IC is providing full constant voltage and constant current characteristics for charging a single 3.7 volt Lithium cell or battery. The TL4056 is ideal chip to do the function. It's charging rate or charging current could be controlled by external resistor on program pin. It has both charging and charge complete sink type input pins where two different color LEDs could be connected to show the status of the chip. The TP4056 IC comes in SOP package and it needs very few external component to function. The less external components and its small size makes it ideal and the best choice to be used in portable applications.

TL4056 IC typical charger circuit

TP4056 can be used in usb applications wall mounted power packs. tp4056 don't need a blocking diode to prevent battery reverse current flow due to internal chip mosfet arrangement. tp4056 has internal thermal protection which prevents chip during high current and high temperature operation or in high ambient temperature. tp4056 output charging voltage at battery terminals are fixed to 4.21V or 4.2 volts. The current rate could be set by a single external resistor. When the charging current reaches to 1/10th of the charging current, the chips stops charging it disconnects battery from charging source. For monitoring two status LED are provides which shows the charging state.

TL4056 or TP4056 charger arrangement

tl4056 ic current programming resistance selection could be done using the following table bellow.

TL4056 IC program current setting resistance values.

The maximum charging current of the tl4056 chip could be programmed 1000mA or 1A linear. There is no need of external mosfet to charge the battery. The internal mosfet inside the chip is enough to accomplish the job. Tl4056 input voltage range is from -0.3V to 10V. TL4056 maximum junction temperature is 144℃ and the working temperature is -40 ℃～85℃

TP4056 SOP pakage

TL4056 charge controller is widely used in digital camera, usb powered chargers, torch lights, battery operated toys, cellphones, cordless telephones, pda, GPS devices, portable devices, charging stations, stroboscope, digital oscilloscope battery powered, multimeters with chargeable batteries and many more.

RM6204 Switching regulation smps power management IC

 

Here in this article we will discuss a small SMPS current mode smps power management IC. RM6204 is a beautiful smps power management IC which is very commonly used in small size smps power supplies and cell phone chargers. RM6204 is a 12W and line voltage regulator IC which is a simple to use and simple to construct single chip smps controller. RM6204 is official IC for Huawei cell phones chargers. This IC RM6204 needs very few external components to function. The power of the smps is limited trough external components like chopper transformer and other resistors and capacitors values. This IC internal switching transistor has capability to withstand 700 volts. The switching transistor can switch 800mA current continues. The overall IC power dissipation is 1000 mW or 1 Watt.

RM6204 SMPS regulator power supply circuit schematic

Above is the circuit schematic for RM6204 smps regulator power supply. Such power supplies are small and suitable for small power needs like cellphone chargers and toys battery chargers. They are capable of providing steady 12 Watts of power. The above circuit is straight forward power supply circuit with feedback loop control. The feed back is observing the output of the circuit and continuously controls the input side PWM signal to regulate the output of the power supply regardless of input voltage changes and output load changes within certain limits. The feedback components are U2, IC3, C20, C6, R8, R9, R10 and R11. These all components makes a feedback loop which regulates the output of the power supply.

RM6204 SMPS controller IC pin connections detail

The above diagram shows the pin connection detail for IC RM6204 smps controller. This IC has 8 pin DIP package. It's available in hole through design.

Here is the internal block diagram of RM6204 IC. RM6204 IC is manufactured by Reactor-Micro semiconductor company.

RM6204 IC block diagram

Here below is RM6204 smps power supply image. This is image for one cellphone charger. You can see only the top side of the power supply board here. Where is this board is smd technology and there are components mounted on the back of the pcb also.

RM6203 IC smps power supply

BLDC motor vs conventional motor

Brushless DC motors are very commonly used now a days. They are everywhere in all equipment used in routine. They are used in computers as cooling fans, hard drive spinning motors and in DVD drives etc. With advent of electric vehicles brushless dc motor use in increased. Brushless dc motor is the best suitable drive motor for many small vehicles drive. Brushless dc motor provides many advantages over regular DC motors and other conventional motors. As these motors have no brushes inside, there are many problems eliminated due to brush removal. Due to brushless design many mechanical problems associated with brushes are also eliminated like friction, maintenance and efficiency problems. As brushed motors have brush and commutator which is worn out component, it could fail catastrophically. In brushless motors the function of the commutator and carbon brush is performed electronically, it is much more reliable and fail proof. As technology has been advance in last few years in rare earth magnets technology and there are very powerful and efficient motors are constructed due to this development which are more powerful and more efficient in same size brushed dc motors.

BLDC Motor running arrangement

Brushless DC motor are run by an electronic controller and the controller supervise all power, voltage and current provides to coils. Also the controller uses PWM to control the speed, power and energy to the motors. These motors could run on both directions from the controller with no difficulties and complexities.

With the advancement in electronics and especially in power electronics, very robust and strong controllers manufacturing is possible. The controllers uses IGBT and Mosfets as output devices which are providing power to the motors. Controllers uses microcontroller with appropriate software to perform all functions required to drive a bldc motor as well as to make necessary pwm signal to power up the bldc motor. There are some special dedicated chips which are used specially to control and run a bldc motor. The very common chip example is FCM8201. This chip has complete detail in its datasheet which shows how to set up the circuit and can make a reliable brushless motor controller.

There is another example of bldc motor controller which is from ON semiconductor MC33033. This chip has complete rotor position circuit integrated inside. So the controller don't need much to run the motor. This chip has capabilty to run 3 phase or 4 phase bldc motors.