Shadow Detector Alarm

This is also known as Sun up alarm, in this circuit you can set the LDR’s sensitivity by 100k potentiometer, you can set it with any lamp around your room (tube light, bulb, LED etc) by varrying the 100k potentiometer. We can also control the buzzer time by 1M potentiometer  
You can Enhance this project and set the sensitivity of the LDR with a lazer light and keep it on the way of any door circuit at one side and lazer at other side of the door and a then you can make this project to buzz as soon as some one enters in a room 

I personally set this project in my room with sensitivity of tube light and whenever i came in and turn my room’s tube light on

Parts Required: 555 Timer 100k & 1M potentiometers  10k, 1Mx(3), 47k 0.1mF, 0.01mF & 10mF LDR BC337 transistor Beeper/Buzzer 9v Battery Supply

   Circuit Diagram:

Bread board Arrangement:     Strip Board Version:      Electronics Lab Created By Muhammad Irfan Electronics Lab Created By Muhammad Irfan

Simple Electronic Lock Project

There are six (or more) push switches. To 'unlock' you must press all the correct ones at the same time, but not press any of the cancel switches. Pressing just one cancel switch will prevent the circuit unlocking. When the circuit unlocks it actually just turns on an LED for about one second, but it is intended to be adapted to turn on a relay which could be used to switch on another circuit.

Please Note: This circuit just turns on an LED for about one second when the correct switches are pressed. It does not actually lock or unlock anything!

This project uses a 555 monostable circuit.

Parts Required

• resistors: 470, 100k ×2, 1M
• capacitors: 0.1µF, 1µF 16V radial
• red LED
• 555 timer IC
• 8-pin DIL socket for IC
• on/off switch
• push-switch ×6 (or more)
• battery clip for 9V PP3
• stripboard 12 rows × 25 holes

Stripboard Layout

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Circuit diagram

Line Following Robot using BC108 Transistors

This is a Line Following Robot and is simplest possible electronic circuit to make your first robot. The key to success of this Circuit is totally depended upon DC geared Motor. Make sure, it is Geared motor. I also first ignored this, and I made whole circuit and fixed it in the structure of the robot, and in the end the RPM and Torque of my non-geared simple dc motors was not proper to move robot efficiently on line. In this robot I have not used any chaster wheel & Strip Sensor part, which are used almost in all line followers. This make this Robot simplest Line Following Robot Ever!! =)

Circuit Diagram:

Parts Required:

1. BC 108 Transistors x (2)
2. N4148 Diode x (2)
3. 10K potentiometer x (2)
4. LDR x (2)
5. DC geared Motors x (2)
6. 9V Battery

Bread Board Arrangement:

One of the most disadvantage of making this circuit is that with only transistors its difficult to control speed of motors. The most common, efficient and reliable method of controlling motor’s speed is through PWM(pulse width modulation) which make the transistor rapid on/off switch. Click here to see: PWM based Line Following Robot using three 555 timers.

Step by Step Procedure to make this Circuit:

Stripboard Version:

By taking advantage of this small and easy circuit, dont miss to make a Strip board version. And by making this little easy solding circuit you will be able to reduce the structure of your robot and make it precise. Best part is, when you use these jumpers then you dont have to make the sensor strip which is commonly made and used in LFRs. I also added a ON/OFF switch in this strip board, so that I have to plug in and plug out the Battery while tuning the sensitivity of LDRs. The reason I left the space beside the circuit is for keeping the 9V battery over it =) 

The motor used in this video is a simple DC motor, I used this one just to show you the output. You have to use the DC geared motor, like ones shown in this figure. The reason for using DC geared motor is that, Geared DC motors have low RPM and high Torque. And they are commonly famous by Robot Motors =) so must Use Geared DC motors for your first robot.

In our case, the method we are using is called as “differential drive steering method”. It is Jerky and shaggy but still works fine! Here is the picture taken from emicro.com which defines this differential drive method properly.

      

The BC108 transistors are designed to be used in their linear region so that the collector current passed through the DC motors will vary according to the base current, which is controlled by LDR+10k trimpot. And like this, DC motor will be given current according to the light intensity received by LDR.

The trimpot is used to adjust the DC motor speed, and N4148 is used to protect the BC108 from EMF generated by motor inductor when it switches off.

The material in the for the track might be different for every other roboticist. So we can always have different track’s route by simply varrrying the 10k 

Trimpot

Zero 2 Nine counter

This is a sequential circuit design, Mod10 means it will count from 0-9. This would be probably your first long circuit, but don’t worry because you have a breadboard arrangement 

555 timer is in astable mode and it will produce a clock pulse, which is controlled by 100k potentiometer.

This clock pulse is input to 74LS90 which is a decade 0-9 ripple counter. Kindly use the 74LS90 if some one tell you that you can alternatively use 74LS93.. so let me tell you though they have same pin configuration and work same but the thing is 74LS93 is 0-15 ripple counter, so you will face some garbage outputs after counting up 0-9 which you don’t want. I tried my best to use 74LS93 and use reset pins to make it Mod 10
well, 74LS90 is a BCD counter but as we are showing a display on 7 segment so we need a driver IC

74LS90 is cascaded to 74LS47 which is a BCD to 7-segment display driver

and at last the seven outputs of 74LS47 are connected to 7 segment display.

Parts Required:

1. 100k(potentiometer), 47k & 1k
2. 0.1mF & 2.2mF
3. 555 Timer
4. 74LS90
5. 74LS47
6. 7 Segment Display Common Anode
7. 9V battery with clip

Circuit Diagram:

Bread board Arrangement:

                

Pin Confiiguration:

  

Electronics Lab  Created By Muhammad Irfan

Electronics Lab  Created By Muhammad Irfan

Line Following Robot Using 555 timer

Traffic Light control

Picture of our Traffic Light Project

This Traffic Light Circuit can be used to control traffic on roads or in public places.In a Traffic light there are three different color bulb which are Green, Yellow/Amber and Red.

 This project uses  IC555 as Astable Multivibrator for rapid squire wave pulse generation. This clock pulse is feed to IC 4017 which is a Counter IC. In this counter IC, for every pulse fed to input pin-14, the High level output keeps shifting from D1 to D9 in cyclic order. See Circuit Diagram below.

At a time one output is higher (Positive) and other output pins of IC remains at low state.

The capacitor and resistor on pin 15 of IC4017 are used to reset the counter to zero (Red light ON) at initial power up.

Part Used:

IC = NE555 ( Timer IC) , IC CD4017 (Counter IC)

Diode = IN4007  6Pcs

POT = 470K

Resistance = 22K, 100K, 220 Ohms X 3Pcs

Capacitor = 0.1 Mfd, 1 Mfd, 10 Mfd.

9 Volt Battery with Snap

Switch, Wire, Clamp, PCB

Electronics Lab  Created By   Muhammad Irfan

Heat Sensor

Electronics Lab Created By Muhammad Irfan

Here is a simple circuit which can be used as a heat sensor. In the following circuit diagram thermistor and 100 Ohms resistance is connected in series and makes a potential divider circuit . If thermistor is of N.T.C (Negative temperature Coefficient ) type then after heating the thermistor its resistance decreases so more current flows through the thermistor and 100 Ohms resistance and we get more voltage at junction of thermistor and resistance. Suppose after heating 110 ohms thermistor its resistance value become 90 Ohms.then according to potential divider circuit the voltage across one resistor equals the ratio of that resistor’s value and the sum of resistances times the voltage across the series combination. This concept is so pervasive it has a name: voltage divider. The input-output relationship for this system, found in this particular case by voltage divider, takes the form of a ratio of the output voltage to the input voltage.
This output voltage is applied to a NPN transistor through a resistance. Emitter voltage is maintain at 4.7 volt with a help of Zener diode.This voltage we will use as compare voltage. Transistor conducts when base voltage is greater than emitter voltage. Transistor conducts as it gets more than 4.7 base Voltage and circuit is completed through buzzer and it gives Sound.

Circuit Diagram of Heat Sensor

* please use 220 Ohms thermistor if not available you can use 2pcs 110 ohms thermistor in series. Resistance parallel with zener diode is not necessary.

You may also be interested in Project using Precision Temperature Sensor .

Electronics Lab Created By Muhammad Irfan

50 555 Timer circuits

THE SIMPLEST 555 OSCILLATOR
The simplest 555 oscillator takes output pin 3 to capacitor C1 via  resistor R1.
When the circuit is turned on, C1 is uncharged and output pin 3 is HIGH. C1 charges via R1 and when Pin 6 detects 2/3 rail voltage, output pin 3 goes LOW. R1 now discharges capacitor C1 and when pin 2 detects 1/3 rail voltage, output pin 3 goes HIGH to repeat the cycle.
The amount of time when the output is HIGH is called the MARK and the time when the output is LOW is called the SPACE.
In the diagram, the mark is the same length as the space and this is called 1:1 or 50%:50%.
If a resistor and capacitor (or electrolytic) is placed on the output, the result is very similar to a sinewave.

C1 to POSITIVE RAIL 
C₁ can be connected to the positive rail. This is not normal practice, however it does work.
The output frequency changes when the capacitor is changed from the negative rail to the positive rail. Theoretically the frequency should not change, but it does, and that's why you have to check everything.  The frequency of operation in this arrangement is different to connecting the components via pin7 because pin3 does not go to full rail voltage or 0v. This means all the output frequencies are lower than those in the "555 Frequency Calculator."
The table shows the frequency for the capacitor connected to the 0v rail and 12v rail:

C1 to 0v rail			C1 to 12v rail
1k	1n	505kHz	1k	1n	255kHz
1k	10n	115kHz	1k	10n	130kHz
1k	100n	23kHz	1k	100n	16kHz
10k	1n	112kHz	10k	1n	128kHz
10k	10n	27kHz	10k	10n	16kHz
10k	100n	3700Hz	10k	100n	1600Hz

 

CHANGING THE MARK-SPACE RATIOThis ratio can be altered by adding a diode and resistor as shown in the following diagrams. In the first diagram, the 555 comes ON ("fires-up") with pin 3 low and pin 2 immediately detects this low and makes pin 3 HIGH. The 10n is quickly charged via the diode and 4k7 and this is why the MARK is "short." When the capacitor is 2/3Vcc, pin 6 detects a HIGH and the output of the 555 goes LOW. The 10n is discharged via the 33k and this creates the long-duration SPACE (LOW). The second diagram creates a long-duration HIGH:

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THE THREE BASIC 555 OSCILLATORSThe 3 basic 555 oscillators are shown in these circuits.
The basic points to remember are these:
Pin 7 goes LOW when pin 3 goes LOW.
Pin 6 detects a HIGH
Pin 2 detects a LOW
Pin 3 can be used instead of the supply-rail to deliver a HIGH and instead of pin 7 to deliver a LOW to the timing section made up of pins 2&6 and "C" and a timing resistor.

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HOW TO REMEMBER THE PINS:

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INSIDE THE 555 

Note: Pin 7 is "in phase" with output Pin 3 (both are low at the same time).
Pin 7 "shorts" to 0v via a transistor. It is pulled HIGH via R1.
Maximum supply voltage 16v - 18v
Current consumption approx 10mA
Output Current sink @5v = 5 - 50mA     @15v = 50mA
Output Current source @5v = 100mA     @15v = 200mA
Maximum operating frequency 300kHz - 500kHz

Faults with Chip:
Consumes about 10mA when sitting in circuit
Output voltage can be up to 2.5v less than rail voltage Output can be  0.5v to 1.5v above groundSources up to 200mA
Some chips sink only 50mA,  some will sink 200mA

A NE555 was tested at 1kHz, 12.75v rail and 39R load. The Results: 
Output voltage 0.5v low, 11.5v high at output current of 180mA The "test chip" performance was excellent.

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THE 555 PINS

Here is the identification for each pin:

When drawing a circuit diagram, always draw the 555 as a building block, as shown below with the pins in the following locations. This will help you instantly recognise the function of each pin: 


Pin 1 GROUND.  Connects to the 0v rail. Pin 2 TRIGGER. Detects 1/3 of rail voltage to make output HIGH. Pin 2 has control over pin 6. If pin 2 is LOW, and pin 6 LOW,  output goes and stays HIGH. If pin 6 HIGH, and pin 2 goes LOW, output goes LOW while pin 2 LOW. This pin has a very high impedance (about 10M) and will trigger with about 1uA.Pin 3 OUTPUT. (Pins 3 and 7 are "in phase.") Goes HIGH (about 2v less than rail) and LOW (about 0.5v above 0v rail) and will deliver up to 200mA.Pin 4 RESET. Internally connected HIGH via 100k. Must be taken below 0.8v to reset the chip. Pin 5 CONTROL. A voltage applied to this pin will vary the timing of the RC network (quite considerably).  Pin 6 THRESHOLD.  Detects 2/3 of rail voltage to make output LOW only if pin 2 is HIGH. This pin has a very high impedance (about 10M) and will trigger with about 1uA.Pin 7 DISCHARGE. Goes LOW when pin 6 detects 2/3 rail voltage but pin 2 must be HIGH. If pin 2 is HIGH, pin 6 can be HIGH or LOW and pin 7 remains LOW. Goes OPEN (HIGH) and stays HIGH when pin 2 detects 1/3 rail voltage (even as a LOW pulse) when pin 6 is LOW.  (Pins 7 and 3 are "in phase.") Pin 7 is equal to pin 3 but pin 7 does not go high - it goes OPEN.  But it goes LOW and will sink about 200mA. You can connect pin 7 to pin 3 to get a slightly better SINK capability from the chip.Pin 8 SUPPLY. Connects to the positive rail.

Electronics Lab Created by Muhammad Irfan 

Electronics Lab Created by Muhammad Irfan 

555 LED DIMMER Circuit

This circuit will adjust the brightness of one or more LEDs from 5% to 95%.



Electronics lab created by Muhammad Irfan 
Electronics lab created by Muhammad Irfan

555 Amplifier Circuit

The 555 can be used as an amplifier. It operates very similar to pulse-width modulation. The component values cause the 555 to oscillate at approx 66kHz and the speaker does not respond to this high frequency.  Instead it responds to the average CD value of the modulated output and demonstrates the concept of pulse-width modulation. The chip gets very hot and is only for brief demonstrations. 


Electronics Lab  created   By   Muhammad Irfan
Electronics Lab  created   By   Muhammad Irfan