Saturday, October 26, 2013

Simple Mobile Phone Jammer Circuit Diagram

                 Circuit showing a mobile phone jammer.Here i have used a fm transistor for making this circuit.Mobile phones are working in 450  MHz  frequency .Here the transmitter generate almost equal to 450 MHz  frequency there for the mobile phone does not identify the original signal but the signal range is very week so this circuit working in only 100 m range .This circuit working in only 450 Mhz .Do not give more than 3 V

Part List
Component No: Value  Usage
R1 100R  Emitter loading
R2 39k   Base Biasing
C115 pf  Frequency
C24.7pf  Feedback
C3 4.7pf  Feedback
C4102pf  Noise Reduce
C5 1MFCoupling
C6 2.2pf  Coupling
C7    103pf    Decoupling 
Q1 BF 494  Amplification
L1 22nH Frequency


* FM Transmission

* TV Transmission

* Remote Controlled Toy

Electronics  lab   ,     Created by Muhammad Irfan

Wednesday, October 23, 2013

Water level controller using 8051

No comments:
A water level controller based using 8051 is shown in this article. A lot of water level controller projects have been published in this website but the is the first one based on a microcontroller. This water level controller monitors the level of the over head tank  and automatically switches on the water pump when ever the level goes below a preset limit. The level of the over head tank is indicated using 5 leds and the pump is switched of when the over head tank is filled. The pump is not allowed to start if the water level in the sump tank is low and also the pump is switched off when the level inside the sump tank goes low during a pumping cycle. The circuit diagram of the water level controller is shown below.
The level sensor probes for the overhead tank are interfaced to the port 2 of the microcontroller through transistors. Have a look at the sensor probe arrangement for the overhead tank in Fig1. A positive voltage supply probe goes to the down bottom of the tank. The probes for sensing 1/4, 1/2, 3/4 and FULL levels are placed with equal spacing one by one above the bottom positive probe. Consider the topmost (full level) probe, its other end is connected to the base of transistor Q4 through resistor R16. Whenever water rises to the full level current flows into the base of transistor Q4 which makes it ON and so its collector voltage goes low. The collector of Q4 is connected to P2.4 and a low voltage at  P2.4 means the over head tank is not FULL. When water level goes below the full level probe, the base of Q2 becomes open making it OFF. Now its collector voltage goes high and high at P2.4 means the tank is not full. The same applies to other sensor probes (3/4, 1/2, 1/4) and the microprocessor understands the current level by scanning the port pins P2.4 ,P2.5, P2.6 and P2.7. All these port pin are high (all sensor probes are open) means the tank is empty.
Port pin P0.5 is used to control the pump. When ever it is required start pumping, the controller makes P0.5 low which makes transistor Q6 ON which in turn activates the relay K1 that switches the pump. Also the LED d6 glows indicating the motor is ON. LED D7 is the low sump indicator. When the water level in the sump tank goes low, the controller makes P0.7 low which makes LED D7 to glow. The circuit diagram of the water level controller is shown in the figure below.

Circuit diagram.



MOV P2,#11111111B // initiates P2 as sensor input
MOV P0,#11111111B // initiates P2 as the output port
MOV A,#00000000B
MAIN:ACALL SMPCK // checks the level of the sump tank
MOV A,P2 // moves the current status of P2 tp A
CJNE A,#11110000B,LABEL1 // checks whether tank is full
CLR P0.0 // glows full level LED
CJNE A,#11111000B,LABEL2 // checks whether tank is 3/4
CLR P0.1 // glows 3/4 level LED
CJNE A,#11111100B,LABEL3 // checks whether tank is 1/2
CLR P0.2 // glows 1/2 level LED
CJNE A,#11111110B,LABEL4 // checks whether tank is 1/4
CLR P0.3 // glows 1/4 level LED
CLR P0.5 // switches motor ON
CJNE A,#11111111B,MAIN // checks whether tank is empty
CLR P0.4 // glows EMPTY LED
JB P0.6,MAIN // checks whether sump is low
CLR P0.5 // switches motor ON
SMPCK:JB P0.6,LABEL5 // checks whether sump is low
SETB P0.7 // extinguishes the sump low indicator LED
LABEL5:SETB P0.5 // switches the pump OFF
CLR P0.7 // glows sump low indicator LED

 Electronics  lab   ,     Created by Muhammad Irfan 




Monday, October 21, 2013

Object counter using 8051

1 comment:

Object counter using 8051 microcontroller.

This article is about a simple object counter/visitor counter using 8051 microcontroller . AT89S51 belonging to the 8051 family is the microcontroller used here. This circuit can count the number of objects passing across a line , number of persons passing through a gate/door and so on. The can be simply divided into two sections i.e. the sensor section and the display section.


The sensor part consists of a ultra bright led (with focus), and LDR, opamp LM324 and the associated passive components. The LED is placed on one side of the door and the LDR is placed on the other side so that the light from the LED falls directly on the LDR.As you know, the resistance of the LDR has an inverse relationship with the intensity of the light falling on it. The preset resistor R14 is so adjusted that the voltage across the LDR is below 1.5V when it is illuminated. This voltage (labelled A in the circuit diagram) is connected to the inverting input of the opamp which is wired as a comparator with reference voltage 1.5V (set using R15 and R16).Capacitor C1 is meant for bypassing noise or anything like that which may cause false triggering.Resistor R13 is meant to control the current through the LED. 

Electronics  lab   ,     Created by Muhammad Irfan
When the light is falling on the LDR the voltage across it will be less than the reference voltage and so the output of the opamp remains high. When the light beam is interrupted, the voltage across the LDR goes above the reference voltage and so the opamp output goes low and it indicates a pass.

Display section.

The output of the opamp is fed to the INTO (interrupt 0) pin of the microcontroller. The microcontroller is programmed to count the number of negative edge pulses received at the INT0 pin and displays it on the three digit seven segment display.

Circuit diagram.


ORG 000H
ORG 003H  // starting address of interrupt service routine (ISR)
ACALL ISR // calls interrupt service routine

INIT: MOV P0,#00000000B
      MOV P3,#11111111B
      MOV P1,#00000000B
      MOV R6,#00000000B
      SETB IP.0     // sets highest priority for the interrupt INT0
      SETB TCON.0   // interrupt generated by a falling edge signal at INT0 pin
      SETB IE.0     //enables the external interrupt
      SETB IE.7     //enables the global interrupt control

      MOV B,#100D
      DIV AB
      SETB P1.0
      MOV A,B
      MOV B,#10D
      DIV AB
      CLR P1.0
      SETB P1.1
      MOV A,B
      CLR P1.1
      SETB P1.2
      CLR P1.2

ISR: INC R6     //interrupt service routine

DISPLAY: MOVC A,@A+DPTR // display sub routine
         CPL A
         MOV P0,A

DELAY: MOV R3,#255D  // 1mS delay
     DB 06H
     DB 5BH
     DB 4FH
     DB 66H
     DB 6DH
     DB 7DH
     DB 07H
     DB 7FH
     DB 6FH

About the program.

The program is written so that, it keeps displaying the current value in register R6 on the three digit seven segment display. When ever there is a valid negative going pulse (interrupt) at the INT0 pin, the program branches to the interrupt service routine (sub routine ISR). Subroutine ISR increments the value in register R6, then jumps back to the MAIN loop and the display gets updated by the new value.


Entire circuit can be powered from a 5V DC supply.
LDR must be placed in an enclosure so that the light from LED alone falls on it.

Electronics  lab   ,     Created by Muhammad Irfan 

Automatic Doorbell with Object Detection Circuit


Automatic Doorbell with Object Detection Circuit


The circuit operates using a pair of ultrasonic transmitter and receiver modules which are used to detect the person. When the person is detected (the person is in the front door), the doorbell is automatically turned ON.


Figure 1  Automatic Door Bell with Object Detection Circuit Diagram

The ultrasonic transmitter operates at a frequency of about 40 kHz, which means it continuously transmits the ultrasonic waves of about 40 kHz. The power supplied should be moderate such that the range of the transmitter is only about one or two meters. If the transmitting power is less than one meter, then there is a possibility that the person who is one meter away will not be detected. Likewise, if the range is set higher, then it may lead to false trigerring which means that objects from afar maybe considered as visitors triggering the circuit. So to avoid these problems, the transmitting power is kept to an optimum level.
The ultrasonic receiver module receives the power with the frequency the same as that of the transmitter so that the noise will be eliminated and minimized false triggering. The sensitivity of the receiver can be tuned by using a 500 kilo-ohm variable resistor arranged as a pot in the circuit. By tuning this properly, we can achieve the desired results. The buzzer circuit is the output load which acts a doorbell in the case. The receiver circuit uses the integrated circuit LM324 which has 4 operational amplifier internally. Out of the four, three operational amplifiers only are being utilized. The three op-amps are arranged in cascade to provide high gain as well as noise free output.
An optocoupler is used at the output to avoid any interaction between the circuit and the doorbell.
Assemble the circuit on a PCB as compactly as possible and then attach it to the main door. You may provide a power supply using a 9 VDC adapter with filtered and regulated output. If the 9 V adapter with regulated output is not available, then we recommend you to use a 12 V unregulated DC adapter with 7809 voltage regulator.

Electronics  lab   ,     Created by Muhammad Irfan Electronics  lab   ,     Created by Muhammad Irfan

Resistance Calculator From Band

No comments:

Calculate the resistance of a 4 band resistor


A resistor is a perhaps the most common building block used in circuits. Resistors come in many shapes and sizes this tool is used to decode information for color banded axial lead resistors.

4 Band Description

The number of bands is important because the decoding changes based upon the number of color bands. There are three common types: 4 band, 5 band, and 6 band resistors. For the 4 band resistor:
Band 1 – First significant digit.
Band 2 – Second significant digit
Band 3 – Multiplier
Band 4 – Tolerance

Resistance Value

The first 4 bands make up the resistance nominal value. The first 2 bands make up the significant digits where:
black – 0
brown – 1
red – 2
orange – 3
yellow – 4
green – 5
blue – 6
violet – 7
grey – 8
white – 9
The 3rd band or multiplier band is color coded as follows:
black – x1
brown – x10
red – x100
orange – x1K
yellow – x10K
green – x100K
blue – x1M
violet – x10M
grey – x100M
white – x1G
gold – .1
silver – .01
An example of a resistance value is:
band 1 = orange = 3,
band 2 = yellow = 4,
band 3 = blue = 1M
value = 34*1M = 34 Mohm

Resistance Tolerance

The fourth band is the tolerance and represents the worst case variation one might expect from the nominal value. The color code for tolerance is as follows:
brown – 1%
red – 2%
orange – 3%
yellow – 4%
green – .5%
blue – .25%
violet – .1%
gray – .05%
gold – 5%
silver – 10%
An example calculating the range of a resistor value is:
If the nominal value was 345 Ohm and the 4th band of the resistor was gold (5%) the value range would be nominal +/- 5% = 32.3 to 35.7

Also Over Here 

Electronics  lab   ,     Created by Muhammad Irfan 
Electronics  lab   ,     Created by Muhammad Irfan
 WEBENCH® Designer

    Enter your power supply requirements:
    DC  AC

    Ambient Temp°C
    Multiple Loads
    Single Output

    Sound Level Indicator

    No comments:
    Electronics  lab   ,     Created by Muhammad Irfan      Electronics  lab   ,     Created by Muhammad Irfan

    This project uses an LM3915 bar-graph IC driving two sets of ten LEDs for a 30dB range. The circuit is unique because it has an additional range of 20dB provided by an automatic gain control to allow it to be very sensitive to low sound levels but it increases its range 20dB for loud sounds.

    The LEDs are operating at 26mA each with the brightness control at maximum, which is very bright. The circuit has a switch to select the modes of operation: a moving dot of light, or a bar with a changing length.

    My prototype has a little 9V Ni-Cad rechargeable battery in it to be portable and the battery is trickle-charged when the project is powered by a 9V AC-DC adapter.

    Circuit Description
    1) The electret microphone is powered by and has a load of R1 from an LM2931 5V low-dropout regulator.

    2) The 1st opamp stage is an audio preamp with a gain of 101.

    3) The 2nd opamp stage is a single-supply opamp which works fine with its inputs and output at ground and is used as a rectifier driver with a gain of 1.8. It is biased at ground. Since it is inverting, when its input swings negative, its output swings positive.

    4) Three 2N3904 transistors are used as emitter-followers:
    a) Q1 is inside the negative feedback loop of the 2nd opamp as a voltage reference for the other two transistors. Hopefully the transistors match each other.
    b) Q2 emitter-follower transistor quickly charges C8 which discharges slower into R13 and is used as a peak detector.
    c) Q3 transistor is the automatic gain control. It is also a peak detector but has slower charge and discharge times. It drives the comparators’ resistor ladder in the LM3915 to determine how sensitive it is. R15 from +5V is in a voltage divider with the ladder’s total resistance of about 25k and provides the top of the ladder with about +0.51V when there is a very low sound level detected. Loud sounds cause Q3 to drive the top of the ladder to 5.1V for reduced sensitivity.

    5) The LM3915 regulates the current for the LEDs so they don’t need current-limiting resistors. In the bar mode with all LEDs lit then the LM3915 gets hot so the 10 ohm/1W resistor R16 shares the heat.

    1) You could use a switch to change the brightness instead of a pot, or leave it bright.
    2) You could use an LM358 dual opamp (I tried it) but its output drops above 4Khz. The MC33172 is flat to 20kHz with this high gain.
    3) You could add a 1uF to 2.2uF capacitor across R5 so the indicator responds only to bass or “the beat” of music. Then an LM358 dual opamp is fine.

    1) The stripboard layout was designed for a Hammond 1591B plastic box with space in the lower end for a rechargeable 9V battery. One bolt holds the circuit board and a second bolt was cut short as a guide.
    2) A second piece of stripboard was used on a diagonal to space the LEDs closely together. A few LEDs needed their rim to be filed slightly to fit.
    3) A third piece of stripboard was used as a separating wall for the battery and it interlocks with the LEDs stripboard to hold it in place.
    4) 11-wire flexible ribbon cable connects to the LEDs.
    5) Use shielded audio from the microphone and a rubber grommet holding it.

    Parts List 
    R2, R3, R5, R7, R8, R10--100k
    R12, R14--100
    R17, R19--390
    P1--10k audio-taper (log) pot

    C1, C4, C8--330nF
    C3, C9--100uF/10V
    5V reg--LM2931AZ5.0

    LEDs--MV8191 super-red diffused
    Electret microphone--two-wire type Box--Hammond 1591B
    Battery--9V Ni-Cad or Ni-MH
    SW1--SPST switch
    Adapter jack--switched

    Electronics  lab   ,     Created by Muhammad Irfan Electronics  lab   ,     Created by Muhammad Irfan Electronics  lab   ,     Created by Muhammad Irfan

    Wednesday, October 16, 2013

    Fm Radio Transmitter

    No comments:
    The FM transmitter is a one of best device .There are some types of Fm Transmitter
    1. Iphone FM transmitter
    2. Wireless FM transmitter
    3.  Android FM transmitter
    4.  Long range FM transmitter
    5.  FM Transmitter 
    Here’s one of the easiest and simplest FM transmitter for amateur and electronics beginners. With this DIY kit, you can transmit your voice or audio over an ordinary FM radio within the FM broadcast band. It is a DIY kit designed by Sagar Sapkota. You can buy this kit from MINIBREAD.COM which is an online webstore operated by BuildCircuit team. The best thing about this transmitter is that you don’t have to make your own inductor for this kit. Making an inductor is bit hard for amateurs. Besides, this kit is not only capable of transmitting voice using microphone but also transmitting music from your music player. - 

    You can use this FM transmitter/microphone in two ways:

    a. Audio transmission using electret microphone: You can transmit your voice to FM radio with the electret microphone. You can also place the transmitter circuit close to any loud speaker so that the microphone picks up the sound and transmits to the tuned FM radio.
    FM transmitter images

    b. Audio transmission connecting speaker stereo jack to audio source: For hearing better sound, you may connect it to your computer, ipod or mp3 player using a speaker jack. The audio of your music players get transmitted to your nearby radio.
    Frequency Range: 88-108MHZ (Frequency can be changed by moving the inductor coil).
    Operating voltage: 1. 5V-9V
    Transmission range: More than 30 meters in open area. The transmission depends upon the length of antenna used. I used just a simple 10cm long wire. The signal can be transmitted even far with longer antenna of length around 50cm.

    Working of the kit:
    FM transmitter schematicElectret microphone (MIC) converts the natural sound signal into the electrical signal. The capacitor C2 is coupled to the base of transistor Q1- S9018 and whenever there is signal from the microphone, the junction capacitance of the transistor changes that contributes to change in oscillation frequency.
    Resistor R1(2.2K) is a microphone MIC bias point resistance, usually value between 2K-5. 6K is preferred, R2 provides biasing to the base of transistor.  C4 and inductor L (5.5 turns coil) make up the oscillator tuning circuit, you can change the value of C4 and L to change the transmission frequency.
    Formula for frequency calculation:
    You can calculate the required frequency on this page.
    Testing of the kit:
    Find an FM radio, turn on the power and volume, adjust the frequency around 88 MHz. Connect the kit to the power supply board, align towards the radio and use a screwdriver to adjust the oscillation coil L until the radio catches the signal. Then slowly increase the distance between the microphone and radio, while properly adjusting the radio (or handset) volume, tuning knob until the clearest sound is heard.
      Electronics Lab ,Created By Muhammad Irfan
      Electronics Lab ,Created By Muhammad Irfan
      Electronics Lab ,Created By Muhammad Irfan

    Thursday, October 10, 2013

    Simple Touch Switch

    1 comment:

    Circuit Notes

    The MPF102 (Q1) can be replaced with a NTE451 or ECG451, but still widely available. JFET-N-CHAN, UHF/VHF AMP
    The 2N3565 (Q1/Q2) can be replace with a 2N2222(A), BC107, BC108, BC109(A/B/C), NTE123A, or ECG123A.
    The TIP31 (Q3) can be replaced with a NTE196 or ECG196, but is a common type and widely available.
    NO suffix.
    The 'Touch Plate' can be anything non corrosive. I use a silver quarter. You can also use a small relay instead of the #53 bulb. The phone number for DigiKey is 1-800-Digi-Key.

    Parts List

    R1 22Meg resistor
    R2 47K resistor
    R3,R4 100K resistor
    R5,R6,R7 2K2 resistor
    C1 Capacitor, 22΅F, 25V
    C2 Capacitor, 22΅F, 25V
    Q1 MPF102
    Q2,Q3 2N3565
    Q4 TIP31
    La1 Bulb, #53 

      Electronics Lab ,Created By Muhammad Irfan     Electronics Lab ,Created By Muhammad Irfan     Electronics Lab ,Created By Muhammad Irfan

    Water level buzzer

    No comments:


    Water Level Buzzer is a simple kit which will buzz when water reaches the sensor level.
    • Input - 9 VDC @ 40 mA
    • Output ??? Buzzer
    • Terminal pins for supply voltage
    • Power-On LED indicator
    • Four mounting holes of 3.2 mm each
    • PCB dimensions 32 mm x 35 mm


    Parts List


      Electronics Lab ,Created By Muhammad Irfan      Electronics Lab ,Created By Muhammad Irfan     Electronics Lab ,Created By Muhammad Irfan