Understanding NOR Gate(CD4001)

Understanding NOR Gate(CD4001)

Summary
CD4001 is the most commonly used Complementary Metal Oxide Semiconductor (CMOS) chip.  It comes in a 14 pin Dual Inline Package (DIP). It has small notch on one side which identifies as pin 1.It consists of 4 independent NOR gate in a single chip. Each gate has 2 inputs and 1 output. Working voltage range of IC is from 5V to 15V. It can deliver approx.10mA at 12V but this can be reduce as power supply voltage reduces.
IC consist of 14 pin in this pin 7 and 14 is connected to battery or DC power supply. Negative is connected to pin 7 and pin 14 is connected to power supply. As we know it has four gates we call it NI1, NI2, NI3, NI4. In first gate NI1 pin 1 and 2 are for inputs and pin 3 is for output. As you can see in the circuit below.     
As we can see in the truth table it will provide the output equal to one when both of the input is low. In another words we will receive the high output when both the signals goes low. And if any the inputs are high we will receive the low output.

Description
The circuit describe below can be used in many application like it can we use as fake light to create an impression that alarm has been fitted or you can use it in your vehicles when your car broke down as it will give eye catching appearance to the car passing near to your vehicle.
To understand the working of NOR gate first built the circuit on breadboard or assemble the circuit on zero PCB  as it require very less components so it can be done easily.
In the diagram above consider that we have supply logic low to pin1 of NI1 as a result we will receive logic 1 in output pin 3 if you have assume pin 2 of NI1 be low. Therefore we will  receive logic 0 at output of pin 4 because 1 is passed to NI2 gate input from pin 3 so whatever may be the input from pin 2 we will receive low at pin 4. This means that we will receive 6V at pin 4. As a result current start following in capacitor and capacitor starts to charging.
Now voltage on pin 8 is also low at this time and assume voltage on pin 9 to be low as a result we will receive high at pin 10 of NI3 which also make pin 12 and 13 of NI4 to high and we will receive low on pin 11 as you can see from truth table and LED connected to it will not glow.
But as capacitor charges voltage on resistor drops to half the power supply NI1 detects a high on in its input pin 2 as a result logic 0 appear on pin 3. Now logic 0 is on pin 5 ad 6 we will receive logic 1 at pin 4 of NI2. As a result pin 8 is also high and now again assume pin 9 to be low now we will receive 0 at output pin of NI3 and as a result output pin ofNI4 will receive high and LED start glowing. From above we can see that for a certain period of time circuit will work and then goes off. Time period of operation can be determine by-T=.7*R*C.
If we assume pin 9 of NI2 to be high then also we will get pin 0 to be high and low as you can now see from truth table.
Component used

IC
CD4001	1
Resistor
R1(2.2)	1
R2(560K)	1
R3(1K)	1
C1(1uF)	1
Miscellaneous
LED1	1

Two Different Sound Generator

Two Different Sound Generator

Summary
This circuit can be used to generate two different sound when you press the switch it will produce two different sounds like morse code. The circuit is built around the CD4060 and CD4001 IC and few more components. IC CD4060 is 14 stage ripple carry binary counter, divider and a oscillator. Its built in oscillator is main feature of this IC that’s why it can be used in numerous application like flasher, clock generator r in timer circuits. And CD4001 is the most commonly used Complementary Metal Oxide Semiconductor (CMOS) chip.  It comes in a 14 pin Dual Inline Package (DIP). It consist of 4 
independent NOR gate in a single chip. Each gate has 2 inputs and 1 output.
As we can see in the truth table it will provide the output equal to one when both of the input is low. In another words we will receive the high output when both the signals goes low. And if any the inputs are high we will receive the low output.
Description
Hear IC1 is working as frequency dividing circuit. In this internal oscillator stage is made using resistor and capacitor which can be connected to pin 11,10 and 9. Hear capacitor is connected to pin 9 and pin 11 and 10 is connected with a capacitor. Most probably pin 10 is connected a variable resistor  so that we can select different frequency range and we are using a fix resistor so that while adjusting pot pin 10 value may not fall to zero. And free pin of all three are connected together.

One thing we must take care that value of resistor connected to pin 10 including variable resistor should be 10times less than resistor connected to pin 11. We have connected to pin 12 reset input to ground for enabling the IC to oscillate. And remaining pin of IC generates oscillation at specific rate. The rate is in multiple of two for the entire sequence of pin out.
Now for understanding the working of circuit in this pin 4 provides the lowest frequency or pulse for highest time interval and pin 7 provides highest frequency or pulse with lowest time interval. In this pin 4 and 7 provides audio signal which is given to pin 1 and 8 of NI1 and NI3 of IC2. Now NI4 control the frequency provide to NI3. Now when control signal matches with NI1 during low frequency at the same time control signal at NI4 is high matches with NI2.Output at pin 3 of NI1 will be in same condition therefore we will get low at both pin of NI2 hence we receive a signal at output which is then amplify by transistor and we will hear two strokes of sound.
Component Required

IC
CD4060	1
CD4001	1
Resistor
R1(200K)	1
R2(10K)	1
Vr1(10K)	1
R4(1K)	1
Capacitor
C1(.1uF)	1
T1(BC547)	1
LS(Loud speaker)	1
S1(Push to on switch)	1

TOGGLE SWITCH

Summary
Many times we require a circuit which will on and off the device by the touch of our hand the benefit using touch sensor is we will not receive shocks. If you want to switch off you night lamp or you want to on or off your motor you can use it by simply connecting a relay at the output.
Description
This circuit is based on NAND gate CD4011 in this we are utilizing only 2 gates of NAND gate and rest two are not used. To understand the working you should know about the truth table of NAND gate are as follows-

Input		Output
A	B
0	0	1
0	1	1
1	0	1
1	1	0

In NAND gate we will get output when any of the input signals go low and if both are high we will not get output in that case.
Working of the circuit is very simple in standby mode both the switch are closed and the current follow through R1 and R2 to ground. When you touch the ON switch pin 1 receive the logic zero at its input now whatever may be the input at pin 2 we will get the high at pin 3.  As you can see from truth table. At this time input at pin 6 is high as OFF switch is not pressed and we also get high at pin 5 because of output from pin 3 is feedback to pin 5 as result we will get 0 at pin 4. And the LED connected to start working.
When you again touch the OFF switch then reverse action will take place means when you press the switch pin 6 will receive 0 at its input and whatever may be the input at pin 5 we will receive a high at pin 4.And at this time pin 1 is at logic high and pin 2 is also high therefore we will receive 0 at pin 3. As a result LED connected at the output will go OFF.
In place of LED you can also connect a relay with the help of a transistor. In this you can use BC547 transistor and use supply voltage according to the relay voltage rating. Always remember that working voltage of IC vary from 5V to 15V so do not supply or use relay of more than 16V otherwise it will destroy y your IC.
If you want to make a touch sensor at your home than take conducting plate it may be copper and glued it to some non-conducting material like wood or plastic in a close proximity to each other so when we touch the sensor with the tip of our finger circuit start working. You can also find the readymade sensor available in market or you can also use push to on switch.
The above application can be done with single touch switch as shown in the circuit diagram below-
Component used

IC
CD4011	1
Resistor
R1,R2(4.7K)	2
R3(330E)	1
C1(.1uF)	1
Miscellaneous
LED	1
Touch switch	1

Periodically On Off Mosquito Repellent

Periodically On Off Mosquito Repellent

Summary

The circuit describes below can be used to on and off the electronic device. The time period for which device remains on is similar to the time period for which it remain off. Therefore we can use it in many applications like many of the mosquito repellent available in market use toxic material to kill mosquitoes which generate poisonous vapor to keep mosquito away from the room which is harmful for our body. Continuous release of vapor may harm our brain. Long exposure to these toxic vapors may cause neurological or related problems.  

Description

Here is a circuit that automatically switches on and off the mosquito repellent after preset time interval, thus controlling the release of toxic vapors into the room. The circuit turns the mosquito repellent periodically ‘on’ and ‘off’ for approximately 2 minutes 30 second each. You can also increase or decrease the time according to your requirement.

In this circuit pin 3 always oscillates back and forth from high to low during one cycle capacitor charge in on direction giving output and again charge in opposite direction to remain off. Consider the case when you on the circuit for first time at this time voltage at pin 3 is zero and voltage at pin 1 and 2 is high which is feed to pin 4 which is also high and pin 5 and 6 initially connected to pin 3 through capacitor and resistor are also low but after some time capacitor connected between pin 3 and 5 start charging with the help of C1 and R1 voltage at pin 3 also start building which is internally connected to pin 12 ad 13 as a result output pin 11 become low and this is supplied to pin 8 and 9 and pin 10 become high and we will get output means transistor start conducting. And the device connected to relay start operating.

After preset interval of time the polarity of the charge across C1 & R1 has reversed. Pin 4 is low and pin 3 is high. C1 again starts to charge once more. But this time in the opposite direction. Since pin 3 is now high and pin 4 is low the junction of C1 & R1 represents the negative side of the capacitor. As the capacitor charges the voltage on this junction will fall. This means that the voltage on pins 5 & 6 will fall. When it falls to just below half the supply voltage the inputs change from high to low. And the output of gate 2 will go high. Pin 4 will take pins 1 & 2 high. So pin 3 will go low.
In other words the first cycle is complete.

If you want to increase the time period just change the value of R1 and C1 and see the deference.

Components
IC
IC1(CD4011)	1
Resistor
R1(4.7M)	1
R2(1K)	1
Capacitor
C1(1uF)	1
Miscellaneous
Relay	1
T1(BC547)	1

Multiutility Fleshing Light

Multiutility Fleshing Light

Summary
The circuit describe below can be used in many application like it can we use as fake light to create an impression that alarm has been fitted or you can use it in your vehicles when your car broke down as it will give eye catching appearance to the car passing near to your vehicle. This circuit can be used for decorative purpose in home. In this circuit you can also increase or decrease the intensity of fleshing LED according to requirement.
Description
To understand the working you should know about the truth table of NAND gate are as follows-

Input		Output
A	B
0	0	1
0	1	1
1	0	1
1	1	0

In NAND gate we will get output when any of the input signals go low and if both are high we will not get output in that case.
In this circuit pin 3 always oscillates back and forth from high to low during one cycle capacitor charge in on direction giving output and again charge in opposite direction to remain off. Consider the case when you on the circuit for first time at this time voltage at pin 3 is zero and voltage at pin 1 and 2 is high which is feed to pin 4 which is also high and pin 5 and 6 initially connected to pin 3 through capacitor and resistor are also low but after some time capacitor connected between pin 3 and 5 start charging with the help of C1 and R1 voltage at pin 3 also start building which is internally connected to pin 12 and 13 as a result output pin 11 become low and this is supplied to pin 8 and 9 and pin 10 become high and we will get output means LED connected to it start conducting.
After preset interval of time depending on the value of capacitor and variable resistor the polarity of the charge across C1 & R1 has reversed. Pin 4 is low and pin 3 is high. C1 again starts to charge once more. But this time in the opposite direction. Since pin 3 is now high and pin 4 is low the junction of C1 & R1 represents the negative side of the capacitor. As the capacitor charges the voltage on this junction will fall. This means that the voltage on pins 5 & 6 will fall. When it falls to just below half the supply voltage the inputs change from high to low. And the output of gate 2 will go high. Pin 4 will take pins 1 & 2 high. So pin 3 will go low. And again LED start fleshing. In other words the first cycle is complete. And again and again this cycle continuous we will get the output.

If you want to increase the time period just change the value of R1 and C1 and see the deference.

Components
IC
IC1(CD4011)	1
Resistor
R1(100K)	1
R2,R3(1K)	1
Capacitor
C1(1uF)	1
Miscellaneous
LED(1-6)	6

Locker Guard

Locker Guard

Summary
Most of the theft happens in mid night when we go into the deep sleep. The circuit presented here can be used as a smart circuit for your cash box that thwarts the theft attempt by activating an emergency alarm. This can be used to trigger any external burglar alarm with the help of relay connected in the output of the circuit.
The circuit is built around a popular NAND gate IC and in this all gates are simply working as an inverter. This circuit utilizes the simple phenomenon of LDR whose resistance vary with the intensity of light fall on it with the help of voltage divider circuit. You can put this small circuit in your locker when somebody will open the locker light will fall on LDR and the circuit starts sounding with the help of buzzer connected to the relay. In this we have also provide a switch so that you can switch off the circuit when not in use it will save your battery power.
Description
The circuit is build around CD4011 with the help of some more components like LDR, Variable resistor, Capacitor, transistor, relay and can be used to protect your valuables from burglary using this simple circuit. It generates warning beep when somebody attempts to open the locker.
To understand the working you should know about the truth table of NAND gate are as follows-

Input		Output
A	B
0	0	1
0	1	1
1	0	1
1	1	0

In NAND gate we will get output when any of the input signals go low and if both are high we will not get output in that case.
Output  of the circuit will depend on the pin 10 every time when it go low relay energizes and for every time pin 10 goes low relay de-energizes. And the state of pin 10 is controlled by the voltage on pin 5 and 6 and voltage on pin 5 and 6 is controlled by the intensity of light falling on LDR.
To understand it properly has a look on truth table. When you on the circuit in locker resistance of LDR high as result voltage on pin 5 and 6 on gate 2 is high and voltage at gate 1 or on pin 1 and 2 is low as a result voltage on output pin 4 of gate 2 is also low which causes the voltage on pin 3 to go high which also make pin 13 and 12 of gate 4 to go high as a result output pin 11 will remain low. And this low is also supplied to pin 8 and 9 of gate 3 and output pin 10 goes high and high on pin 10 means relay will remain in de-energize mode and alarm will not sound.
In this we can see that all gates are just working as an inverter if they are receiving logic high output is low and if they are receiving logic low output is high.
When somebody tries to open the locker as light fall on LDR it resistance start decreasing and voltage on pin 5 and 6 reduces to zero as a result voltage on pin 4 become high which will also make pin 1 and 2 high and voltage on pin 3 ,13 and 12 drops to zero  and pin 11,8 and 9 become high and voltage on pin 10 becomes low and relay energizes to sound an alarm that somebody is there.
In other words - while pins 5 & 6 remain low - the relay will remain energized. And the opposite of it also true.
We are controlling the voltage on pin 5 and 6 with the help of voltage divider rule. R1 & R2 form a potential divider with the LDR. We can set the sensitivity of our circuit with the help of R1.Hear you can remove R2 but if R1 were accidentally adjusted to zero ohms - there's a chance that excess current might destroy the LDR. We are using a diode with the relay because any reverse-voltage spikes will be short-circuited at source and they can do any damage.

Components
IC
IC1(CD4011)	1
Resistor
R1(1K)	1
R2(100K)	1
R3(4.7K)	1
Capacitor
C1(.1uF)	1
Miscellaneous
Relay	1
T1(BC547)	1
LDR	1
D1(1N4007)	1

Fridge Door Alarm

Fridge Door Alarm

Summary
It is very important that you should keep close your fridge door all the time. If they are left open they will no longer do their job. Sometimes it happens we forget to close the door properly in that condition it will give you an alarm that you have not close it. This alarm circuit will allow you to open and close the door without sounding the buzzer but if it has been left open more than the pre-set time it will give an audio visual alarm.
CD4011 is the most commonly used Complementary Metal Oxide Semiconductor (CMOS) chip.  It comes in a 14 pin Dual Inline Package (DIP). It has small notch on one side which identifies as pin 1.It consists of 4 independent NAND gate in a single chip. Each gate has 2 inputs and 1 output. Working voltage range of IC is from 5V to 16V. It can deliver approx.10mA at 12V but this can be reduce as power supply voltage reduces.
IC consist of 14 pin in this pin 7 and 14 is connected to battery or DC power supply. Negative is connected to pin 7 and pin 14 is connected to power supply. As we know it has four gates we call it NI1, NI2, NI3, NI4. In first gate NI1 pin 1 and 2 are for inputs and pin 3 is for output. As you can see in the circuit below.
As we can see in the truth table it will provide the output equal to one when any one of the input is low. In another words we will receive the high output when any of the signals goes low. And if both the inputs are high we will receive the low output.
Description
Working of circuit is very simple in standby mode switch SW1 is closed and the current flowing through R1 is grounded through switch. This mean that pin 1 is low and C1 is discharged. As pin 1 is low pin 3 should be high as you can have a look in truth table (we will get output when any of the signal go low). If pin 3 is high pin 5 and 6 is also high and pin 4 remains low. The buzzer will not sound.
When SW1 is open the current flowing through R1 is not grounded now. It is now used to charge C1 as a result voltage on pin 1 begin to rise as capacitor charges. The period of charging depends on the value of C1 and R1 used in our circuit it may take approx. 1 minute after that pin 1 goes high. When it goes high automatically pin 3 becomes low and pin 4 becomes high and alarm start sounding. It will sound until we will close the door again.
Here we have use reed switch with magnet but you can use any switch that suits your requirement.

Components
IC
IC1(CD4011)	1
Resistor
R1(2.2ME)	1
R2.R3,R4(4.7K)	3
Capacitor
C2(.1uF)	1
C1(1uF)	1
Miscellaneous
Reed Switch	1
T1(BC547)	1
Buzzer	1
LED	1