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Showing posts from April, 2013


This function generator, based on an LT016 high-speed comparator, will generate from a single +5-V supply. The slow rate of the op amps used determines the maximum useable frequency of this circuit.


Soldering Instructions


Unlike most sine-wave shapers, this circuit is temperature stable. It varies the gain of a transconductance amplifier to transform an input triangle wave into a good sine-wave approximation.


U2 is a decade counter/divider. U1 is used as a switch debouncer. For a self-generating system, connect a resistor between pins 2 and 3 of a U1 value that should be between 10 k ohm and several M ohm, depending on desired frequency. C1 can also be varied to change frequency. Also, S1 can be omitted in the self-generating version.

Fridge door Alarm

Beeps if you leave open the door over 20 seconds 3V battery operation, simple circuitry R1____________10K 1/4W Resistor R2___________Photo resistor (any type) R3,R4________100K 1/4W Resistors C1____________10nF 63V Polyester Capacitor C2___________100µF 25V Electrolytic Capacitor D1,D2_______1N4148 75V 150mA Diodes IC1___________4060 14 stage ripple counter and oscillator IC Q1___________BC337 45V 800mA NPN Transistor BZ1__________Piezo sounder (incorporating 3KHz oscillator) SW1__________Miniature SPST slide Switch B1___________3V Battery (2 AA 1.5V Cells in series)This circuit, enclosed into a small box, is placed in the fridge near the lamp (if any) or the opening. With the door closed the interior of the fridge is in the dark, the photo resistor R2 presents a high resistance (>200K) thus clamping IC1 by holding pin 12 high. When a beam of light enters from the opening, or the fridge lamp illuminates, the photo resistor lowers its resistance (<2K), pin 12 …

Speech Amplifier

Parts:P1______________22K Log. Potentiometer R1_______________1M 1/4W Resistor R2______________15K 1/4W Resistor R3_____________470R 1/4W Resistor R4______________47K 1/4W Resistor R5,R6____________4K7 1/4W Resistors (Optional, see Notes) C1,C2,C4_______100nF 63V Polyester or Ceramic Capacitors C3______________10nF 63V Polyester or Ceramic Capacitor (See text) C5_____________220µF 25V Electrolytic Capacitor C6______________10µF 25V Electrolytic Capacitor (Optional, see Notes) Q1____________BC547 45V 100mA General purpose NPN Transistor IC1_________TDA7052 Audio power amplifier IC J1______________3mm or 6mm Mono Jack socket SW1____________SPST Slider Switch fitted in the microphone (Optional, see text) SW2____________SPST Toggle or Slider Switch SPKR______________4-8 Ohm Loudspeaker (See Notes) B1_______________6V Battery (4 x AA or AAA 1.5V Cells in series or any 6V rechargeable battery pack etc.) This circuit is intended to be pla…


The circuit has both square-wave and triangle-wave output. The left section is similar in function to a comparator circuit that uses positive feedback for hysteresis. The inverting input is biased at one-half the Vcc voltage by resistor R4 and R5. The output is fed back to the non-inverting input of the first stage to control the frequency. The amplitude of the square wave is the output swing of the first stage, which is 8V peak-to-peak. The second stage is basically an op amp integrator. The resistor R3 is the input element and capacitor C1 is the feedback element. The ratio R1/R2 sets the amplitude of the triangle wave, as referenced to the square-wave output. For both waveforms, the frequency of oscillation can be determined by the equation:
fo= 1/4R3C1 * R2/R1
The output frequency is approximately 50 Hz with the given components.


A tapped-coil Colpitts oscillator is used at Q1 to provide four tuning ranges from 1.7 to 3.1 MHz, 3.0 to 5.6 MHz, 5.0 to 12 MHz and 11.5 to 31 MHz. A Zener diode (D2) is used at Q1 to lower the operating voltage of the oscillator. A small value capacitor is used at C5 to ensure light coupling to the tuned circuit. Q2 is a source-follower buffer stage. It helps to isolate the oscillator from the generator-output load. The source of Q2 is broadly tuned by means of RFC1. Energy from Q2 is routed to a fed-back, broadband class-A amplifier. A 2 dB attenuator is used at the output of T1 to provide a 50 ohm termination for Q3 and to set the generator-output impedance at 50 ohms. C16, C17 and RFC2 form a brute-force RF decoupling network to keep the generator energy from radiating outside the box on the 12 V supply.

555 timer with LED


This circuit works well in the range of 50 kHz to 500 kHz. Slight component modifications are needed for higher frequency operation. For operation over 3000 kHz, select a transistor that provides moderate gain (in the 60 to 150 range) at the frequency of operation and a gain-bandwidth product of at least 100 MHz.


1. 1 M ohm < R1 < 5 M ohm. 2.Select R2 and C2 to prevent spurious frequency. 3.ICs are 74C04 pr equivalent.


1.Y1 is "AT" cut, fundamental, or overtone crystal. 2.Tune L1 and C2 to operating frequency.


This circuit has a frequency range of 0.5 Mhz to 2.0 Mhz. Frequency can be adjusted to a precise value with trimmer capacitor C2. The second NOR gate serves as an output buffer.

Ramp Generator

The 566 can be wired as a positive or negative ramp generator. In the positive ramp generator, the external transistor driven by the Pin 3 output rapidly discharges Cl at the end of the charging period so that charging can resume instantaneously. The pnp transistor of the negative ramp generator likewise rapidly charges the timing capacitor Cl at the end of the discharge period. Because the circuits are reset so quickly, the temperature stability of the ramp generator is excellent. The period
Tis1/2 fo
where f, is the 566 free-running frequency in normal operation. Therefore,
T=1=Rt C1 Vcc 2fo5(Vcc - Vc)
whereVc is the bias voltage at Pin 5 and Rt is the total resistance between Pin 6 and Vcc. Note that a short pulse is available at Pin 3. (Placing collector resistance in series with the external transistor collector will lengthen the pulse.)


Q1 acts as a Colpitts crystal oscillator, and if the crystal under test is operational, the RF signal is rectified by D1 and D2, turning on Q2 and lighting indicator LED2. LED1 is a power indicator

FM Bug Detector

This circuit can be used to "sweep" an area or room and will indicate if a surveillance device is operative. The problem in making a suitable detector is to get its sensitivity just right; too much and it will respond to radio broadcasts, too little sensitivity and nothing will be heard.

This project has few components, can be made on veroboard and powered from a 9 volt battery for portability. 

Circuit operation is simple. The inductor is a moulded RF coil, value of 0.389uH and is available from Maplin Electronics, order code UF68Y. (See my links page for component suppliers.) The coil has a very high Q factor of about 170 and is untuned or broadband. With a test oscillator this circuit responded to frequencies from 70 MHz to 150 MHz, most of the FM bugs are designed to work in the commercial receiver range of 87 - 108 MHz. The RF signal picked up the coil, and incidentally this unit will respond to AM or FM modulation or just a plain carrier wave, is rectified b…

WAP to find the cube of the number in the range 0h to fh

org 0h
mov r0,#20H
mov a,@r0                 ;num in 20h is loaded into acc and b reg
mov 0f0h,a
mul ab                         ;find the square of the no.
mov 0f0h,@r0
mul ab                       ;multiply square of the no. by the get the cube.
mov 030h,a                   ;lower order product in 30h
mov 031h,0f0h               ;higher order product in 31h
here: sjmp here

Basic PICAXE parameters

Here are some of the most useful parameters of the PICAXE:
• The PICAXE requires 5 volts DC, regulated.

• The inputs and outputs of the PICAXE are compatible
with 5-volt logic chips. You can attach them directly.
• Each PICAXE pin can sink or source up to 20mA. The
whole chip can deliver up to 90mA. This means that
you can run LEDs directly from the pins, or a piezo
noisemaker (which draws very little current), or a
• You can use a chip such as the ULN2001A Darlington
array (mentioned in the previous experiment) to amplify
the output from the PICAXE and drive something
such as a relay or a motor.
• The chip executes each line of your program in about
0.1 milliseconds.
• The 08M chip has enough flash memory for about 80
lines of program code. Other PICAXE chips have more
• The PICAXE provides 14 variables named b0 through
b13. The “b” stands for “byte,” as each variable occupies
a single byte. Each can hold a value ranging from 0
through 255.
• No negative or fract…

WAP to convert BCD to ASCII

org 0h
start: mov r0,#20h       ;r0 pointing to src location,loaded with a BCD no.
mov a,@r0                ;no. moved to accumulator and added 30h to get equivalent
add a,#30h
mov 40h,a                  ;result stored at 40h
sjmp start

WAP to convert given hex no. to equivalent decimal no.

org 0h
mov dptr,#5fffh
movx a,@dptr
mov 0f0h,#064h                ;Load B reg with 100d or 64h
div ab                              ;Hundreds
inc dptr
movx @dptr,a            ;store in external ram
mov a,0f0h                 ;remainder from b reg to acc
mov 0f0h,#0ah          ; Load B reg with 10d or 0ah
div ab;
inc dptr;
movx @dptr,a            ;store tens in external ram
inc dptr
mov a,0f0h
movx @dptr,a               ;store units in ext ram
here: sjmp here

WAP to move a block of data within the internal RAM

Org 0h
start1: mov r0,#40h    ;r0 pointed to internal RAM 40h
mov r1,#30h             ;r1 pointing to internal RAM 030h
mov r2,#5                   ;r2 loaded with no. of elements in the array
mov a,@r0                ;data transfer
mov @r1,a
inc r0
inc r1
djnz r2,start                   ;decrement r2,if not equal to 0,continue with data
                                       ;transfer process.
Sjmp Start1

Byte and word data transfer in different addressing modes

DATA2 DW 1234H
DATA5 DW 2345H,6789H
START: MOV AX,DATA   ;Initialize DS to point to start of the memory
MOV DS,AX                  ;set aside for storing of data
MOV AL,25X             ;copy 25H into 8 bit AL register
MOV AX,2345H          ;copy 2345H into 16 bit AX register
MOV BX,AX           ;copy the content of AX into BX register(16 bit)
MOV CL,AL              ;copy the content of AL into CL register
MOV AL,DATA1        ;copies the byte contents of data segment
                                   ;location DATA1 into 8 bit AL
MOV AX,DATA2       ;copies the word contents of data segment memory
                                  ;location DATA2 into 16 bit AX
MOV DATA3,AL          ;copies the AL content into the byte contents of data
                                   ;segment memory location DATA3
MOV DATA4,AX      ;copies the AX content into the word contents of
                                ;data segment …


Writing an ALP
Assembly level programs generally abbreviated as ALP are written in text editor EDIT.
Type EDIT in front of the command prompt to open an untitled text file.
EDIT<file name>
After typing the program save the file with appropriate file name with an extension .ASM
Ex: Add.ASM
Assembling an ALP
To assemble an ALP we needed executable file calledMASM.EXE. Only if this file is in
current working directory we can assemble the program. The command is
If the program is free from all syntactical errors, this command will give the OBJECT file. In
case of errors it list out the number of errors, warnings and kind of error.
Note: No object file is created until all errors are rectified.
After successful assembling of the program we have to link it to get Executable file.
The command is
LINK <File name.OBJ>
This command results in <Filename.exe> which can be executed in front of the command
Executing the Program
Open the program in debugger by …


Max Karl Ernst Ludwig Planck, (April 23, 1858 – October 4, 1947) was a German theoretical physicist who originated quantum theory, which won him the Nobel Prize in Physics in 1918.

Planck made many contributions to theoretical physics, but his fame rests primarily on his role as originator of the quantum theory. This theory revolutionized human understanding of atomic and subatomic processes, just as Albert Einstein’s theory of relativity revolutionized the understanding of space and time. Together they constitute the fundamental theories of 20th-century physics. Both have led humanity to revise some of its most cherished philosophical beliefs,[citation needed] and have brought about industrial and military applications that affect many aspects of modern life.

Propagation modes in radio communication

Propagation Modes::
· Ground-wave propagation
o Follows contour of the earth
o Can Propagate considerable distances
o Ground Wave = Direct Wave + Reflected Wave + Surface Wave
o At MF and in the lower HF bands, aerials tend to be close to the ground (in terms of
wavelength). Hence the direct wave and reflected wave tend to cancel each other
out (there is a 180 degree phase shift on reflection). This means that only the
surface wave remains.
o A surface wave travels along the surface of the earth by virtue of inducing currents in
the earth. The imperfectly conducting earth leads to some of its characteristics. Its
range depends upon: Frequency, Polarization, Location and Ground Conductivity.
o The surface waves dies more quickly as the frequency increases:

· Sky-wave propagation
o Signal reflected from ionized layer of atmosphere back down to earth
o Signal can travel a number of hops, back and forth between ionosphere and
earth’s surface
o Reflection effect caused by refraction
· Line-of-Sight propagat…

Some important parameters in radio communication

· A duct is something that will confine whatever is traveling along it into a narrow
· The atmosphere can assume a structure that will produce a similar effect on radio
waves. When a radio wave enters a duct it can travel with low loss over great
distances. The atmosphere will then act in the manner of a giant optical fiber,
trapping the radio wave within the layer of high refractive index.
· A wave trapped in a duct can travel beyond the radio horizon with very little loss,
producing signal levels within a few dB of the free-space level.
· When an electromagnetic wave is incident on a rough surface, the wave is not so
much reflected as “scattered”.
· Scattering is the process by which small particles suspended in a medium of a
different index of refraction diffuse a portion of the incident radiation in all directions.
· Scattering occurs when incoming signal hits an object whose size in the order of the
wavelength of the signal or less.
· Reflection occurs …

Multipath in radio Communication

· Multipath is a term used to describe the multiple paths a radio wave may follow
between transmitter and receiver. Such propagation paths include the ground wave,
ionospheric refraction, reradiation by the ionospheric layers, reflection from the
Earth's surface or from more than one ionospheric layer, etc.
· If the two signals reach the receiver in-phase (both signals are at the same point in
the wave cycle when they reach the receiver), then the signal is amplified. This is
known as an “upfade.” If the two waves reach the receiver out-of-phase (the two
signals are at opposite points in the wave cycle when they reach the receiver), they
weaken the overall received signal. If the two waves are 180º apart when they reach
the receiver, they can completely cancel each other out so that a radio does not
receive a signal at all. A location where a signal is canceled out by multipath is called
a “null” or “downfade.”

· If the reflecting surfaces that cause the multipath situation do not mo…

Fading and its types

· There is a large dependence of fading on distance.
o The probability of a fade of a particular depth increases with the cube of
distance. Thus, as the distance is doubled, the probability of a particular fade
depth increases by a factor of eight. Or, alternatively, the fade for a given
probability increases by 9 dB. So, doubling the distance will increase the freespace
loss by 6 dB, and increase the probability of fading by 9 dB, thus
increasing the overall link-budget loss by 15 dB.
· There is a slight dependence of fading on frequency. Increasing the frequency by
1GHz will decrease the probability of a fade by a factor of 1.08.
· There is a fairly strong dependence of fading on the height of the path above sea
o There is simply less atmosphere at higher altitudes and therefore the effect of
atmospheric fading is smaller.
o For every 1000 meter increase in altitude the required fade margin reduces by
10 dB.
· Types of Fading
o Fast fading - occurs when the coherence time of the chan…

Diversity Techniques

Diversity Techniques::
Fade margin on the transmitter path is not an efficient solution at all, and one alternate
solution is to take the advantage of the statistical behavior of the fading channel.
This is the basic concept of Diversity, where two or more inputs at the receiver are used
to get uncorrelated signals.

· Frequency Diversity
o Different frequencies means different wavelengths. The hope when using
frequency diversity is that the same physical multipath routes will not produce
simultaneous deep fades at two separate wavelengths.

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blackberry z10 vs lumia 920 vs Iphone 5 vs rivals
finally here it comes.....
one table to rule them all..features,specs....and much more :)
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History of Electronics Timeline


1745     Capacitor Leyden

1780     Galvanic action Galvani

1800     Dry cell Volta

1808     Atomic theory Dalton

1812     Cable insulation Sommering and Schilling

1820     Electromagnetism Oersted