Fixed Bias Transistor Circuits

Few Points: Two batteries vBB and VCC used VBB gives potential to base terminal through RB. VCC  supplies power to the collector through RC. Base resistance RB  of the order of hundred kilo ohm Collector resistance RC of the order of kilo ohm. Aim: To find dc base current IB, IC, VCE and IE  For this purpose, we are going to convert  above circuit in electrical equivalent circuit. For making calculation easy, we divide this circuit in two part, (i) Input Part and (ii) Output Part (I)  Input Part:Applying KVL:We get, VBB = IBRB + VBEOr  IB = ( VBB – VBE )/ RBFor Silicon Transistor, VBE = 0.7 V and For Ge Transistor, VBE = 0.3 V (ii) Output Part: Applying KVL...

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Posted in: Electronics,transistor

Biasing of Transistor:

Need of Biasing: The proper flow of zero signal collector current and the maintenance of proper collector emitter voltage during the passage of signal is called the transistor biasing. It is essential for faithful amplification. If the transistor is not biased properly, It would be Work inefficiently  Produce distortion in the output signal. Keep in Mind: Input side should be in Forward Biased Output side should be in Reverse Biased Base Resistance RB >>RC There are some transistor biasing circuits:Fixed Bias Potential Divider Bias Two Supply Emitter Bias Emitter – Feedback Bias Collector Feedback Bias Collector – and Emitter – Feedback Bias ...

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Posted in: Electronics,transistor

Troubleshooting of a Transistor circuit

Troubleshooting  a circuit:1.       Measure the Vce. 2.       When troubles come, they are usually big troubles like shorts or opens. 3.       Short: when  devices damaged, solder splashes across resistors. 4.       Open: when components burn out. 5.       These troubles produce large changes in voltages and currents  Welcome to S2P Group. For more information. connect to study2placement.blogspot.comCause of these troubles:1.       Trouble in the power supply2.       An open lead between the power supply and the...

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Posted in: Electronics

Projects Based on C++

There are some useful projects for Computer Science students: Shop Bill Based on C++ Snake Game Based on C++ Address Book Based on C++ Company Details Based on C++ Diabetes Detection Based on C++ Railway Reservation Based on C++ Alternative Railway Reservation Based on C++...

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Posted in: cpp

Electronic mosquito repeller

Here is the circuit diagram of an ultrasonic mosquito repeller.The circuit is based on the theory that insects like mosquito can be repelled by using sound frequencies in the ultrasonic (above 20KHz) range.The circuit is nothing but a PLL IC CMOS 4047 wired as an oscillator working at 22KHz.A complementary symmetry amplifier consisting of four transistor is used to amplify the sound.The piezo buzzer converts the output of amplifier to ultrasonic sound that can be heard by the insects. Circuit diagram : Main Parts Used: IC CD4047 ( a Phased Lock Loop) - 1 4 Transistor ( 2 NPN (SL100) and 2 PNP (SK100)) Capacitors ( 4.7 nF, 22uF 16V) 10K Potentiometer - 1 Welcome to S2P Group. For more details: www.study2placement.blogspot.com Note Assemble...

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Posted in: Electronics,Mosquito Repellent,PLL

How does the Timer 555 work

Block diagram for the 555 timer is given in fig. Main Parts of 555 Timer: Two comparators (simply Op-Amp) An R-S Flip-flop Two Transistors A Resistive networks consisting three equal resistors and acts as a voltage divider Working: In most applications, the control pin is not used, so that the control voltage equals +2Vcc/3 . Output of comparator 1 is applied to set (S) input of the flip-flop. Whenever the threshold voltage exceeds the control voltage, comparator 1 will set the flip-flop and its output is high. A high output from the flip-flop saturates the discharge ttransistor and discharge the capacitor connected externally to pin 7. The complementary signal out of the flip-flop goes to pin 3, the oputput. The output available at pin...

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Posted in: 555,Electronics

How a Capacitor Works

An electrical capacitor is made of two small conductive plates separated by what is called a dielectric, which effectively insulates the two plates and stops any current from being transferred between the plates themselves. Instead, the two plates are connected through a circuit. When the circuit is taken out, the plates store the electrical current because it can't flow between the plates. The way a capacitor works is like a water storage tank with a shut-off valve if it gets too full. As electrical current enters the capacitor, the capacitor lets it pass through unaffected. However, the more current flows into the capacitor, the quicker it "fills." This then triggers the capacitor's shut-off mechanism, preventing electrical current from...

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Posted in: Electronics

How Inductor works

When a current flows into an inductor, it doesn't go round and round and round the turns, taking its time to get to the other end. An inductor wound with 100 feet of wire behaves nothing like a 100 foot wire. Why? It's because when the current begins flowing, it creates a magnetic field. This field couples to, or links with, the other turns. The portion of the field from one turn that links with the others is the measurable quantity called the coefficient of coupling. For a good HF toroid, it's commonly 99% or better; solenoids are lower, and vary with aspect ratio. The field from the input turn creates a voltage all along the wire in the other turns which, in turn, produce an output current (presuming there's a load to sustain current flow)....

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Posted in: Electronics

50% DUTY CYCLE OSCILLATOR

For  a  50%  duty  cycle,  the  resistors  RA    and  RB    may  be connected as in Figure 14. The time period for the output high is the same as previous, t1  = 0.693 RA  C. For the output low it is t2  = Thus the frequency of oscillation isNote that this circuit will not oscillate if RB  is greater than 1/2 RA   because the junction of RA   and RB   cannot bring pin 2 down to 1/3 VCC  and trigger the lower comparator.ADDITIONAL INFORMATIONAdequate power supply bypassing is necessary to protect associated circuitry. Minimum recommended is 0.1µF in parallel with 1µF electrolytic. Lower  comparator  storage...

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Posted in: 555,Electronics

LINEAR RAMP using 555

When the pull up resistor, RA, in the monostable circuit is replaced  by  a  constant  current  source,  a  linear  ramp  is generated. Figure 1 shows a circuit configuration that will perform this function. Welcome to S2P Group. Figure 2 shows waveforms generated by the linear ramp. The time interval is given by: VBE  . 0.6V For more informations: www.study2placement.blogspot.comVCC  = 5VTIME = 20µs/DIV.R1  = 47kΩR2  = 100kΩRE  = 2.7 kΩC = 0.01 µF...

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Posted in: 555,Electronics

PULSE POSITION MODULATOR

This application uses the timer connected for astable operation, as in Figure 1, with a modulating signal again applied to the control voltage terminal. The pulse position varies with the modulating signal, since the threshold voltage and hence the time delay is varied. Figure 2 shows the waveforms generated for a triangle wave modulation signal. VCC  = 5V TIME = 0.1 ms/DIV. RA  = 3.9kΩ RB  = 3kΩ C = 0.01µ...

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Posted in: 555,Electronics

PULSE WIDTH MODULATOR

When the timer is connected in the monostable mode and triggered  with  a  continuous  pulse  train,  the  output  pulse width can be modulated by a signal applied to pin 5. Figure 1  shows  the  circuit,  and  in  Figure  2  are  some  waveform examples. VCC  = 5VTIME = 0.2 ms/DIV.RA  = 9.1kΩC = 0.01µF...

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Posted in: 555,Electronics

ASTABLE OPERATION

If the circuit is connected as shown in Figure 1  (pins 2 and 6 connected) it will trigger itself and free run as a multivibrator. The external capacitor charges through RA   + RB   and discharges through RB. Thus the duty cycle may be precisely set by the ratio of these two resistors. In this mode of operation, the capacitor charges and discharges between 1/3 VCC   and 2/3 VCC. As in the triggered mode, the charge and discharge times, and therefore the frequency are independent of the supply voltage. Figure 2 shows the waveforms generated in this mode of operation.VCC  = 5VTIME = 20µs/DIV.RA  = 3.9kΩRB  = 3kΩC = 0.01µFThe charge time (output high) is given by: t1  = 0.693 (RA...

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Posted in: 555,Electronics

MONOSTABLE OPERATION using 555

In this mode of operation, the timer functions as a one-shot (Figure 1). The external capacitor is initially held discharged by a transistor inside the timer. Upon application of a negative trigger pulse of less than 1/3 VCC  to pin 2, the flip-flop is set which both releases the short circuit across the capacitor and drives the output high. For More information: www.study2placement.blogspot.com The voltage across the capacitor then increases exponentially for a period of t = 1.1 RA  C, at the end of which time the voltage  equals  2/3  VCC.  The  comparator  then  resets  the flip-flop which in turn discharges the capacitor and drives the output to its low state. Figure...

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Posted in: 555,Electronics

LM555 Timer

The LM555 is a highly stable device for generating accurate time delays or oscillation. Additional terminals are provided for triggering or resetting if desired. In the time delay mode of operation, the time is precisely controlled by one external resistor and capacitor. For astable operation as an oscillator, the  free  running  frequency  and  duty  cycle  are  accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output circuit can source or sink up to 200mA or drive TTL circuits. Pin 1: Grounded Terminal: All the voltages are meas­ured with respect to this terminal. Pin 2: Trigger Terminal:...

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Posted in: 555,Electronics

UM66TXXL series Musical IC

MELODY INTEGRATED CIRCUIT DESCRIPTION The   UTC   UM66TXXL   series   are   CMOS   LSI designed for using in door bell,  telephone  and toy application.  It  is  an  on-chip  ROM  programmed  for musical     performance.     Produced     by     CMOS technology,  the  device  results  in  very  low  power consumption.   Since   the   UTC   UM66TXXL   series include oscillation circuits a compact melody module can   be   constructed   with   only   a   few   additional components. FEATURES 64-Note Rom memory consumption Dynamic speaker can be driven with external NPN transistor OSC...

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Posted in: Electronics

BPW77 as Phototransistor

Silicon NPN Phototransistor  DESCRIPTION BPW77 is a silicon NPN phototransistor with high radiant sensitivity in hermetically sealed TO-18 package with base terminal and glass lens. It is sensitive to visible and near infrared radiation. FEATURES • Package type: leaded • Package form: TO-18 • Dimensions (in mm): Ø 4.7 • High photo sensitivity • High radiant sensitivity • Suitable for visible and near infrared radiation                 • Fast response times                 • Angle of half sensitivity: ϕ = ± 10°                 • Base terminal connected                ...

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Posted in: Electronics,transistor

CXA1619BM/BS a FM/AM radio IC

CXA1619BM/BS is a one-chip FM/AM radio IC designed for radio-cassette tape recorders and headphone tape recorders, and has the following functions. Features • Small number of peripheral components. • Low current consumption (VCC=3 V) For FM : ID=5.8 mA (Typ.) For AM : ID=4.7 mA (Typ.) • Built-in FM/AM select switch. • Large output of AF amplifier. EIAJ output=500 mW (Typ.) when VCC=6 V, load impedance 8 Ω Function FM section • RF amplifier, Mixer and OSC (incorporating AFC variable capacitor). • IF amplifier • Quadrature detection • Tuning LED driver AM section • RF amplifier, Mixer and OSC (with RF AGC) • IF amplifier (with IF AGC) • Detector • Tuning LED driver AF section • Electronic volume control Structure Bipolar monolithic IC Recommended...

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Posted in: Audio,Electronics

Mobile robot with sonar scanner

Robot uses stepper motor to rotate the sonar sensor and it covers 180 degree. Each 45 degree, a sample is taken. There is a LED display which works like radar, and shows the detected obstacles. Moreover, Robot can switch to remote control mode. So,we can simply control the motion and get samples using RF transmitter. Circuit Diagram: Download Source Code of Micro controller using C                                         Downloa...

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Posted in: Microcontroller

Infrared entry alert door

An IR transmitter and IR receiver placed at either side of a doorway sends and receives IR stream. If the beam is broken, a buzzer will beep or a relay will trigger. Please read "readthis!.txt" for all information. Welcome to S2P Community. Circuit Diagram: Transmitter: Receiver: Everything included, source, assembler, programmer, and Receiver and Emitter datasheets in docs folder.                                          Downl...

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Posted in: Microcontroller

Testing semiconductors with multimeters

Before building any circuit is it a good idea to test every semiconductor you plan to use in the project. This a good practice especially when reusing components from old appliances. This short tutorial describes common procedures for testing of Si and Ge signal and rectifier diodes, Zener diodes, LEDs, Bipolar and MOSFET transistors for common failures like shorts, leaks and opens.Testing signal and rectifier diode junctionsA regular signal or rectifier diode should read a low resistance on an analog ohmmeter (set on the low ohms scale) when forward biased (negative lead on cathode, positive lead on anode) and nearly infinite ohms in the reverse bias direction. A germanium diode will show a lower resistance compared...

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Posted in: Electronics