Basic Electronics/Electrical Projects & Kits

Get our latest collection of basic electronics projects here -- all tested and reviewed for use in mini projects and main projects or even just as hobbyist projects!
Simple Automatic Water Level Controller Save Rs. 45.00

Simple Automatic Water Level Controller

by KNS Pvt Ltd
Save Rs. 45.00
Rs. 225.00
Rs. 180.00

Summary

This is a simple Automatic water controller Kit which the users can assemble in minutes and starting experimenting with it. The circuit is built around a TIMER555 and a inverting buffer CD4049. Circuit works on a 12V DC supply. Three sensors are installed with the kit to indicate lower level, higher level and VCC. At bottom of the tank VCC is placed,lower level L is placed above the VCC and higher level H is placed at the top.

Get the kit now and build yourself a reliable water controller and get amazed by how this tiny little device takes care of water level in the tank!!

Learning

Things Which you can learn:

*Application of NE555 timer.
*Application of CD4069 as inverter.
*Application and connection of relay switches to control the on/off of appliances.

Product Description

Water-level controllers are common nowadays and have become essential device in conserving water which otherwise would get wasted as the tank gets full up to its brim. The one described here is built around timer NE555 and inverter buffer CMOS IC CD4049. It uses readily-available, low-cost components, and is easy to build and install on the over-head tank (OHT) to prevent wastage of water.

Working


The circuit works off a 12V battery or 230V AC mains using a 12V adaptor. Since Vcc terminal is at the bottom of the tank, when the water level falls below sensor L, timer IC2 is triggered at pin 2 via inverters N1 and N2 and its output goes high. As a result, the output of timer IC2 goes high. Relay RL1 energises and the motor starts filling water in the tank. The motor remains ‘on’ even when the water level crosses sensor L.

As water in the tank rises to touch sensor H, timer IC2 is retriggered at pin 6 via inverters N3 and N4 and as a result, its outputgoes low. The relay de-energises and
the motor stops filling water in the tank. The motor remains ‘off’ even when the water level falls below sensor H. As water is consumed and its level falls below sensor L, the motor restarts.Thereafter, the cycle repeats.

Brand: Kits'n'spares, Marketed by: Kits'n'spares

 

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Periodically On Off Mosquito Repellent Save Rs. 20.00

Periodically On Off Mosquito Repellent

by KNS Pvt Ltd
Save Rs. 20.00
Rs. 119.99
Rs. 99.99

Summary

Some of the mosquito repellents available in the market use a toxic liquid to generate poisonous vapors in order to repel mosquitoes out of the room. Due to the continuous release of poisonous vapors into the room, after midnight the natural balance of the air composition for good health reaches or exceeds the critical level.

Mostly, these vapors attack the brain through the lungs and exert an anesthetic effect on mosquitoes as well as other living beings by small or greater percentage. Long exposure to these toxic vapors may cause neurological or related problems.Here is a circuit that automatically switches on and off the mosquito repellent after a preset time interval, thus controlling the release of toxic vapors into the room.

Learning

Things which you can learn:

*Application of NE 555 timer.
*Application of TRIAC BT136.
*Application of Zener diode as a voltage regulator.

Product Description

Here is a circuit that automatically switches on and off the mosquito repellent after the preset time interval, thus controlling the release of toxic vapours into the room. The circuit turns the mosquito repellent ‘on’ for approximately 20 minutes then process of 'on' and 'off' occurs repeatedly.So if you leave the mosquito repellent switched on from 10 pm to 6 am (eight hours), it will be ‘on’ for four hours and ‘off’ for four hours of the total duration. During ‘off’ time, the room air tries to balance its natural composition.

Another important feature is that the circuit switches to ‘on’/‘off’ operation without producing any noise or a sound click as in a relay and hence doesn’t disturb your sleep.

Working

The circuit consists of a timer section built around IC 555 (IC1) and an automatic switching section using Triac BT136 (triac1). Power supply to the circuit is derived from the AC mains by stepping it down to a required level and rectifying it. The elimination of the transformer saves on space as well as money. Zener diode ZD1 and capacitor C2 provide regulated 9V DC power supply to timer IC1.The timer section comprises resistors R1 and R2 and capacitor C1.

The output of timer IC 555 is fed to the gate terminal of BT136 through series LED1 and resistor R4. When the timer output goes high, it triggers the gate of Triac 1 and LED1 shows the ‘on’ period. During ‘off’ time, the output of IC1 goes low and hence Triac 1 is not fired and LED1 doesn’t glow. The circuit is very compact and can be assembled on a general-purpose PCB. Use an 8-pin IC base for timer IC LM555. After assembly, fit the unit inside the housing electric board where you plug in the mosquito repellent.

 

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Fastest Finger First Indicator Save Rs. 25.00
Rs. 400.00
Rs. 375.00

Fastest Finger First Indicator

Fastest Finger First Indicator

by KNS Pvt Ltd
Save Rs. 25.00
Rs. 400.00
Rs. 375.00

Summary

Build a Fastest Finger First Indicator with this simple kit interactive and use it in a quiz and game shows for indicating which player reacted or answered the fastest. The number assigned to the player is displayed by the circuit along with an alarm sound while the fastest finger buttons of the other contestant are locked.

Learning

Things Which you will Learn :

*Basics and implementation of Priority Encoder IC 7475.
*Concept and implementation of Latch
*Basics and implementation of hex inverter gates with IC 74LS04
*Concept of Binary Coded Decimal and BCD to 7 segment display IC 7447
*Concept and implementation of Frequency oscillator with NE555 IC

Product Description

The Fastest Finger First Indicator circuit determines as to which of the four contestants pressed the button first and locks out the entries from the remaining three contestants. Simultaneously, an audio alarm and the correct decimal number display of the corresponding contestant are activated.

Working


When a contestant presses his switch, the corresponding output of the latch IC 7475(IC2) changes its logic state from 1 to 0. The combinational circuitry comprising dual 4-input NAND gates of 7420 (IC3) locks out subsequent entries by producing the appropriate latch-disable signal. Priority encoder IC 74147(IC4) encodes the active-low input condition into the corresponding binary coded decimal (BCD) number output. The outputs of IC4 after inversion by inverter gates inside hex inverter 74LS04 (IC5) are coupled to BCD-to-7-segment decoder/display driver 7447(IC6). The output of IC6 drives common common-anode 7-segment LED display (DIS.1, FND507 or LT543).

The audio alarm generator comprises of the frequency oscillator NE555 (IC7), whose output drives a loudspeaker. The oscillator frequency can be varied with the help of preset VR1. Logic 0 state at one of the outputs of IC2 produces logic 1 input condition at pin 4 of IC7, thereby enabling the audio oscillator.
IC7 needs +12V DC supply for sufficient alarm level. The remaining circuit operates on regulated +5V DC supply, which is obtained using IC1 (7805). Once the organizer identifies the contestant who pressed the switch first, he disables the audio alarm and at the same time forces the digital display to ‘0’ by pressing reset push button S5.

Click To View Circuit Diagram

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Sunset Lamp
Rs. 100.00

Sunset Lamp

Sunset Lamp

by KNS Pvt Ltd
Rs. 100.00

Summary

This kit is based on the principle of Light dependent resistor . Thus when the sun sets the ambient light in the environment decreases and thus the light glows up.

Learning

Things which you will learn:

*Application of NE555 in bi stable mode.
*Concepts related to the working of Light Dependent Resistors.
*Application of TRIAC BT136.
*Application of Zener Diode.

Product Description

Build this automatic sunset light , which will light up when its dusk and will help in conserving electricity .

Working

The circuit uses popular timer IC NE555 as a Schmitt trigger to give the bistable action. The set and reset functions of the comparators within the NE555 are used to give the instantaneous action. The upper threshold comparator of IC1 trips at 2/3Vcc, while the lower trigger comparator trips at 1/3Vcc.The inputs of both the threshold and the trigger of NE555 are tied together and connected to the voltage divider formed by LDR1 and
VR1. The voltage across LDR1 depends on the light intensity.

In daylight, LDR1 has low resistance and the input voltage to the threshold comparator goes above 2/3Vcc and its output becomes zero, and the lamp remains off.
At sunset, the resistance of LDR1 increases, and the voltage at the input of the threshold comparator decreases below 2/3Vcc and that of the trigger comparator goes below 1/3Vcc. As a result, the outputs of threshold and trigger comparators go high. Thus it completes the power supply to the lamp through triac1. LED1 glows to indicate the high output state.

 

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Speed Checker For Highways

Speed Checker For Highways

by KNS Pvt Ltd
Rs. 650.00

Summary

While driving on highways, motorists tend to exceed the maximum permissible speed limit set by the traffic department. The speed checker implemented here is a low cost solution which will allow the traffic policemen to monitor speeds. The Speed Checker for Highways displays a digital reading corresponding to the vehicle’s speed and also sounds an alarm if the vehicle exceeds the permissible speed for the highway.


The speed-sensing is done by the means of two laser transmitter-LDR sensor pairs. These are installed on the highway 100 meters apart, with the transmitter and the LDR sensor of each pair on the opposite sides of the road. The system displays the time taken by the vehicle to cross this 100m distance from one pair to the other with a resolution of 0.01 second. The speed of the vehicle can be calculated from the simple speed-time-distance equation.

Learning

*Application of the NE555 timer in the monostable and astable mode.

*Application of the decade counter/7-segment decoder IC CD4026.

Product Description

The Speed Checker Kit for Highways is a simple kit based on 555 Timer IC, NAND gate inverter, Decade counter and 7 segment display to calculate the speed of vehicles , plying on the road.


Working


The Speed Checker for Highways implemented here assumes that the maximum permissible speed for highways is either 40Kmph or 60Kmph as per the traffic rule. For 40kmph limit the time period is set for 9 seconds using preset VR1, while for 60kmph limit the time period is set for 6 seconds using preset VR2. Slide switch S1 is used to select the time period as per the speed limit i.e. either 40Kmph or 60Kmph. The junction of LDR1 and resistor R1 is coupled to pin2 of IC1. Normally, light from the laser keeps falling on the LDR sensor continuously and thus the LDR offers a low resistance and pin2 of IC1 is high.


Whenever light falling on the LDR is interrupted by any vehicle, the LDR resistance goes high and hence pin 2 of IC1 goes low to trigger the monostable. As a result, output pin3 goes high for the preset period, either 9 or 6 seconds, and LED1 glows to indicate it. Reset pin 4 is controlled by the output of NAND gate N3 at power-on or whenever reset switch S2 is pushed. For IC2, the monostable is triggered in the same way as IC1 when the vehicle intersects the laser beam incident on LDR2 to generate a small pulse for stopping the count and for use in the speed detection. LED2 glows for the duration for which pin 3 of IC2 is high.


The outputs of IC1 and IC2 are fed to input pins 2 and 1 of NAND gate N1, respectively. When the outputs of IC1 and IC2 go high simultaneously i.e. the vehicle has crossed the preset speed limit, output pin 3 of gate N1 goes low to trigger mono-stable timer IC3. The output of IC3 is used for driving piezoelectric buzzer PZ1, which alerts the operator of speed-limit violation.


Resistor R9 and capacitor C5 decide the time period for which the piezoelectric buzzer sounds. The output of IC1 triggers the bistable (IC4) through gate N2 at the leading edge of the count-start pulse. When pin2 of IC4 goes low, the high output at its pin 3 enables astable clock generator IC5. Since the count-stop pulse output of IC2 is connected to pin6 of IC4 via diode D1, it resets clock generator IC5. IC5 can also be reset via diode D2 at power-on as well as when reset switch S2 is pressed.

Click To View Circuit Diagram

 

 

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Smoke Alarm Save Rs. 25.00
Rs. 200.00
Rs. 175.00

Smoke Alarm

Smoke Alarm

by KNS Pvt Ltd
Save Rs. 25.00
Rs. 200.00
Rs. 175.00

Summary

Most smoke detecting circuits available commercially, make use of expensive smoke sensors which require complicated interfacing circuitry around them. However, the Smoke Alarm implemented here is capable of detecting smoke consistently and employs a simple phototransistor optical interrupter switch as the smoke sensor. This smoke-detecting circuit utilizes the simple fact that in case smoke is present, the optical signal transmitted from the infrared emitting diode to the photo-transistor (both part of the photo interrupter module) will be interrupted. Once such a situation is encountered, an alarm sound is generated by the loudspeaker till the time smoke clears. Number of ICs used: 1.

Learning

Things Which you can learn:
*Application of the phototransistor optical interrupter switch H21A1
*Implementation of the astable mode of the NE555 timer IC.

Product Description

The smoke alarm circuit employs a simple mechanism to detect smoke in the vicinity and sound an alarm. The sensing is done by the photo-transistor optical interrupter switch while the alarm is sounded by the NE555 timer IC, the output of the former acts as the input of the latter.

Working

In the absence of any smoke, the gap of the photo-transistor interrupter housing is clear and the infrared light from the diode falls directly onto the photo-transistor. This keeps the photo-transistor of the optical interrupter module in saturation. Owing to this, the reset pin (active LOW) of the NE555 IC is pulled to ground and it continuously resets the NE555 timer IC. No output is generated at pin3 and hence the loudspeaker does not sound an alarm.

In case of smoke, the gap between the diode and the photo-transistor gets clouded with smoke and the optical signal is interrupted. (The threshold value of the least detectable smoke density is decided by the variable resistor VR1). This interruption in the optical signal causes the base voltage of photo-transistor to fall and cut-off. As a result, the collector terminal of the photo-transistor as well as the reset pin (pin no.4) of the NE555 IC is held high via resistor R2. Hence, oscillations are generated at the output pin (pin no.3) of the NE555, the frequency of which is decided by the value of R3, R4 and C1. This electrical signal (oscillations) is input to the loudspeaker through the capacitor C3 and is further converted into a loud and continuous alarm sound.

Click To View Circuit Diagram

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Automatic Night Lamp Dimmer with Morning Alarm Save Rs. 75.00

Automatic Night Lamp Dimmer with Morning Alarm

by KNS Pvt Ltd
Save Rs. 75.00
Rs. 300.00
Rs. 225.00

This automatic night lamp serves a dual purpose, depending on the intensity of light rays detected. The circuit is capable of automatically switching ‘ON’ a white LED on detecting darkness, to act as a night lamp. Conversely, it can also sense daylight and play a melodious tune as a morning alarm. The circuit operates on AC supply and the circuit also provides for battery backup in case of power failure.

No. of ICs used: 3

Learning from this project

  • Application of NE555 timer IC in monostable mode.
  • Concepts related to the working of light dependent resistors.
  • Implementation of bridge rectifier circuit for AC to DC conversions.
  • Application of the music generator IC UM66.

Product Description

This project builds an automatic lamp with night dimmer and morning alarm. It can set the ambient light of your room and also wake you up when the sun rises.

Working

The automatic night lamp dimmer with morning alarm is powered by a standard 0-9V transformer. Diodes (D1-D4) rectify the AC voltage and the resulting DC voltage is smoothed by a capacitor (C1). Voltage regulator IC (7806) provides regulated 6V DC supply to the circuit while battery backup is also provided to power the circuit when mains fails. When mains supply is available, a 9V rechargeable battery charges via a diode (D5) and a resistor (R1) with a reasonably constant current. In the event of a power failure, the battery automatically takes up the load without delay.

The circuit uses light dependent resistors (or LDR) for sensing ambient light conditions. Typically, an LDR offers high resistance in darkness, which reduces to a minimum when bright light is incident on it. In this automatic night lamp dimmer circuit, one LDR (LDR1) detects darkness while another LDR (LDR2) detects light in the morning.

The circuit is designed around the single timer IC NE555 (IC2), which is configured to work in the monostable mode in the circuit. IC2 is activated by a low pulse applied to its trigger input (pin 2). Once triggered, the output pin (pin 3) of IC2 goes high and remains in that position until IC2 is triggered again by the input at pin 2. When LDR1 is illuminated by the ambient light, its resistance falls to a minimum and pin 2 (trigger input) of IC2 remains at a positive potential. This causes the output (pin 3) of IC2 to go low and hence, the white LED remains off.

In absolute darkness, the LDR has a resistance in excess of 280-kilo ohms. So, when the resistance of LDR1 increases, a short pulse is applied to trigger input (pin2) of IC2 via a resistor (R2).

This triggers the monostable mode of operation and the output pin of the NE555 (IC2) goes high, causing the white LED to glow. A low-value capacitor (C2) maintains the monostable for continuous operation, eliminating the timer effect. By increasing the value of C2, the ‘ON’ time of the white LED can be adjusted. LDR2 and associated components generate the morning alarm at dawn. LDR2 detects the ambient light in the room at sunrise and its resistance gradually falls. This makes a transistor (T1) to start conducting. When T1 conducts, a melody-generator IC UM66 (IC3) gets supply voltage from the emitter of T1 and it starts producing the melody. A single-transistor amplifier (T2) amplifies the musical tone generated by IC3.

Click To View Circuit Diagram

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6 in 1 Gift Box Save Rs. 101.00
Rs. 700.00
Rs. 599.00

6 in 1 Gift Box

6 in 1 Gift Box

by KNS Pvt Ltd
Save Rs. 101.00
Rs. 700.00
Rs. 599.00

The Gift box contains 5 electronic project kits and a soldering kit to make them. Gift Box has one each of the following kits;

  • Musical Touch Bell
  • Musical Door Bell
  • Water Level Indicator
  • Burglar Alarm
  • Magic Eye
  • Soldering Kit

Learning from the kit

Things you can learn,

  • Application of the melody generator IC BT66 (or UM66).
  • Application of PNP and NPN type transistors for switching purposes.
  • Application and implementation of the NE555 timer IC in the astable mode.
  • Principle involving the use and function of LDRs (Light Dependent Resistors) and their application.
  • Hands on experience of soldering different components.

Product Description

The 6 in 1 gift box is a complete kit for those keen on developing quality electronic projects. It contains 5 projects which test your skills at a different level. It also contains a soldering kit required to complete this kit. This box opens up a great opportunity for learning.

Musical Touch Bell: The Musical Touch Bell implemented here can be operated by just bridging the gap between two touch plates by one’s fingertips and requires minimal power consumption. The circuit generates a pleasant musical tone through a melody generator IC, as long as the touch plates are in contact.

Musical Door Bell: Most conventional doorbells available in the market generate alarm for a specific time duration which cannot be reprogrammed or controlled. This can be annoying when a person has answered the door immediately. The musical doorbell (with memory) implemented here is a simple doorbell whose ringing duration can be varied easily. The circuit generates a pleasant musical tone for a preset time duration after the toggle switch is pressed.

Water Level Indicator: The purpose of a water level indicator is to caution when a water tank has been filled up to a particular level. This circuit exploits the simple fact that water is a good conductor of electricity. The system is capable of indicating the water level in two ways- visual (by the means of an LED) and audible (by the means of a sound generated by a piezoelectric buzzer).

Burglar Alarm: The burglar alarm implemented here is a simple circuit that sounds an alarm on detecting intrusion. The system is implemented by installing a simple sensing loop, which is basically a thin copper wire. This way, the loop is both invisible and brittle enough to break easily and initiate the alarm mechanism. At the time of an intrusion, the loop breaks causing the loudspeaker to generate a continuous and loud alarm sound.

Magic Eye: It can be used for a variety of applications like a burglar alarm, smoke detector or an automatic guest indicator. All these applications make use of the Light Dependent Resistor (LDR) which is installed and implemented differently in each case.

Soldering Kit-Contains basic tools for soldering.

Cellphone Detector Mobile Bug Save Rs. 50.00
Rs. 300.00
Rs. 250.00

Cellphone Detector Mobile Bug

Cellphone Detector Mobile Bug

by KNS Pvt Ltd
Save Rs. 50.00
Rs. 300.00
Rs. 250.00

Summary

This handy, pocket-size mobile transmission detector can sense the presence of an activated mobile phone from distance of one and- a half meters. So it can be used to prevent the use of mobile phones in examination halls, confidential rooms, etc. It is also useful for detecting the use of mobile phone for spying and unauthorized video transmission.

Learning

Things which you can learn:

*Working of CA3130 as current to voltage converter.
*Application of transistor as an amplifier.
*Application of NE555 as an amplifier.

Product Description

Build yourself a mobile detecting bug and become an expert in finding out hidden mobile phones in sensitive areas like LPG godown etc.

Working:

The circuit can detect both the incoming and outgoing calls, SMS and video transmission even if the mobile phone is kept in the silent mode.The circuit uses a 0.22μF disk capacitor (C3) to capture the RF signals from the mobile phone.The disk capacitor along with the leads acts as a small gigahertz loop antenna to collect the RF signals from the mobile phone.

Op-amp IC CA3130 (IC1) is used in the circuit as a current-to-voltage converter with capacitor C3 connected between its inverting and non-inverting inputs.

When the mobile phone signal is detected by C3, the output of IC1 becomes high and low alternately according to the frequency of the signal as indicated by LED1. This triggers monostable 555timer.

 

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“What’s Included In This Box”.

 

S.No Component Quantity
1   Capacitor 22pF ceramic 2
2   Capacitor 0.22uF ceramic 1
3   Capacitor 100uF 25V electrolytic 1
4   Capacitor 47pF ceramic 1
5   Capacitor 0.1uF ceramic 2
6   Capacitor 0.01uF ceramic 1
7   Capacitor 4.7uF 25V electrolytic 1
8   IC CA3130 1
9   IC NE 555 1
10   LED RED 1
11   Piezzo Buzzer 1
12   Resistor 2.2M 2
13   Resistor 100K 1
14   Resistor 1K 1
15   Resistor 12K 1
16   Resistor 15K 1
17   Tr BC548 1
18   switch on/off 1
19   8-pin base 2
20   Antenna 1
21   PCB - AB4380 - Cell Phone Detector 1

 

Automatic School Bell Save Rs. 50.00
Rs. 300.00
Rs. 250.00

Automatic School Bell

Automatic School Bell

by KNS Pvt Ltd
Save Rs. 50.00
Rs. 300.00
Rs. 250.00

This automatic school bell finds use in educational institutes, factories and organizations where accurate time keeping and bell timings are necessary. This circuit automatically sounds an alarm 8 times, at intervals of 45 minutes each. After 4 intervals, a 30-minute lunch break or recess is also timed/belled for.

No. of ICs used : 4

Learning from the project

  • Application of decade counter IC CD4017.
  • Application of the AND gate IC CD4081 for logic conversion. 
  • Application of the NE555 timer IC in the astable mode of operation. 
  • Application of relays and SCRs for switching operations.

Product description

Time keeping has been an integral part of educational institutions and big factories. Build this kit which will automatically ring, at preset times, to inform students and employees. This is a simple automation project which you can bring to your school.

Circuit operation

To begin time keeping and initiate the bell mechanism using the automatic school bell circuit, the peon needs to momentarily press switch S1 to mark the beginning of the first period. Thereafter, the bell sounds every 45 minutes to indicate the end of consecutive periods, except immediately after the fourth period, when it sounds after 30 minutes to indicate the completion of lunch break. When the last period is over, LED2 glows to indicate that the bell circuit should now be switched off manually. In case the peon has been late to start the school bell, the delay in minutes can be adjusted by advancing the time using switch S3. Each push of switch S3 advances the time by 4.5 minutes. If school closes early, peon can turn the bell circuit off by momentarily pressing switch S2.

The bell circuit contains timer IC NE555 (IC1), two CD4017 decade counters (IC2 and IC3) and an AND gate CD4081 (IC4). The NE555 (IC1) is wired as an astable multi-vibrator whose clock output pulses are fed to IC2. IC2 increases the time periods of IC1 (4.5 and 3 minutes) by ten times to provide a clock pulse to IC3 every 45 minutes or after 30 minutes, respectively. When the class periods are going on, the outputs of an IC3 switch on transistors T1 and T2 via diodes D4 through D12.

Resistors R4 and R5 connected in series to the emitter of NPN transistor T2 decide the 4.5-minute time period of IC1. The output of IC1 is further connected to pin 14 of IC2 to provide a period with a duration of 45 minutes. Similarly, resistors R2 and R3 connected in series to the emitter of NPN transistor T1 decide the 3-minute time period of IC1, which is further given to IC2 to provide the lunch-break duration of 30 minutes. Initially, the circuit does not ground to perform its operation when a 12V power supply is given to the circuit. When switch S1 is pressed momentarily, a high enough voltage to fire silicon-controlled resistor SCR1 appears at its gate.

When SCR1 is fired, it provides a ground path to operate the circuit after resetting both decade counters, IC2 and IC3. At the same time, LED1 glows to indicate that school bell is now active. When switch S2 is pressed momentarily, the anode of SCR1 is again grounded and the circuit stops operating. In this condition, both LED1 and LED2 don’t glow. When the eighth period is over, the Q9 output of IC3 goes high. At this time, transistors T1 and T2 don’t get any voltage through the outputs of IC2. As a result, the astable multivibrator (IC1) stops working. The school bell sounds for around 8 seconds at the end of each period. One can increase/decrease the ringing time of the bell by adding/removing diodes connected in series across pins 6 and 7 of IC1.

The terminals of the 230V AC electric bell are connected to the normally open (N/O) contact of relay RL1.

Click To View Circuit Diagram

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Anti-Theft Alarm for Vehicles Save Rs. 100.00
Rs. 400.00
Rs. 300.00

Anti-Theft Alarm for Vehicles

Anti-Theft Alarm for Vehicles

by KNS Pvt Ltd
Save Rs. 100.00
Rs. 400.00
Rs. 300.00

This anti theft alarm for vehicles is a security system for vehicles that generates a loud and continuous alarm in case any unauthorized person tries to gain access to your vehicle. As soon as a thief tries to start the ignition, the vehicle alarm is activated, leaving no option other than to flee as the alarm can be reset and turned OFF by the owner alone. Build this kit to prevent theft of your vehicle.

Learning from this project

  • Application of music generator IC UM3561
  • Application of NPN transistors for switching purposes
  • Application of SCRs for sensing and switching
  • Application of capacitors for temporary storage

Product description

The anti theft alarm for vehicles simulates a police siren whenever someone attempts to commit theft of your vehicle. The alarm sounds continuously for a few seconds even when the intruder switches off the ignition key.

Circuit working

The circuit consists of an SCR based trigger circuit and an audio alarm circuit. When the ignition key of the vehicle is switched off, the base voltage of the NPN transistor SL100 (T1) is low and it remains off. When the ignition key is switched on for starting the vehicle, a positive voltage is applied to the base of transistor T1 through diode D1, toggle switch (S2) and a resistor (R1) which slowly charges the 100 microfarad capacitor (C1). As a result, the base voltage of T1 rises.

As soon as the biasing voltage crosses cut-in voltage, T1 turns on and the SCR fires, giving 12V DC voltage to the alarm circuit. The alarm circuit is built around the music generator UM3561 (IC1) which has an inbuilt oscillator. The output from IC1 is fed to a transistor amplifier built around transistors BC548 (T2) and SL100 (T3). The circuit gives sufficient time delay to switch ON the alarm and leave the vehicle. The alarm once triggered, sounds until the toggle switch S1 is pressed to switch off the power supply.

A 220 microfarad capacitor (C2) is provided to sound the alarm even when the intruder switches off the ignition key. When the ignition key is switched off immediately, C2 discharges through a resistor R4 and keeps the alarm activated for half a minute. Reset switch (S3) is used to reset the alarm if needed.

Click To View Circuit Diagram

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Smart Emergency Light Save Rs. 75.00
Rs. 300.00
Rs. 225.00

Smart Emergency Light

Smart Emergency Light

by KNS Pvt Ltd
Save Rs. 75.00
Rs. 300.00
Rs. 225.00

Summary

Now you need not fear dark nights when power breaks down. Here’s a white LEDbased Emergency light that automatically turns on when the mains power supply fails.

Learning

Things which you can learn:

*Application of NE555 inastable mode.
*Application of LDR in light and dark.
*Application of bridge rectifier.

Product Description

Build an Emergency light which will automatically switch on when the power fails, thus obviating the need to search the light and switch it on manually!!

Working


The switching circuit is built around an NE555 timer (IC1), which is wired in monostable mode. When a low voltage is applied at trigger pin 2 of IC1, the timer activates and its output pin 3 goes high. It remains in that state until IC1 is triggered again at its pin 2. Light-dependant resistor LDR1 is connected between the positive supply of the battery and trigger pin 2 of IC1. Resistor R3 is connected between pin 2 of IC1 and ground. The resistance value of LDR1 remains high in the dark (at night) and low in ambient light (in daytime). This phenomenon is utilised to control the switching circuit.

The working of the circuit is simple. In daytime, when ambient light falls on LDR1, its resistance decreases to make trigger pin 2 of IC1 high. As a result, output pin 3 goes low and the LEDs(LED1 through LED7) remain off. At night (in the dark), the resistance of LDR1 increases and a low voltage is applied to trigger pin 2 of IC1. This activates the monostable and its output goes high to make all the LEDs glow.

 

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Long Range Burglar Alarm Using Laser Torch Save Rs. 75.00

Long Range Burglar Alarm Using Laser Torch

by KNS Pvt Ltd
Save Rs. 75.00
Rs. 450.00
Rs. 375.00

Summary

Most laser torch based burglar alarms work in darkness only. But this Long Range Burglar Alarm can work reliably in the daytime as well to alert you about intruders and burglars. The Burglar Alarm comprises of the laser transmitter and receiver units, to be mounted on the opposite pillars of the possible entry points. Whenever anyone enters to interrupt the transmitted laser beam falling on the receiver, the buzzer in the receiver circuit sounds an alarm. No. of ICs used: 1 Note-Laser torch will not be provided by KnS.

Learning

Things which you can learn:

*Application of NPN transistors for switching purposes.
*Use of the Photo-Darlington 2N5777 for sensing purposes.
*Application of the NE555 timer IC as a multivibrator to generate oscillations of a particular frequency.

Product Description

The range of the Burglar Alarm is approximately 30 meters, which means that the transmitter and receiver units can be placed up to 30 meters apart. Since the laser torch can transmit light up to a distance of 500 meters, this range can be increased by proper orientation of the photo-transistor. However, to avoid false triggering by sunlight, the photo-transistor should be mounted in such a way that it doesn’t directly face sunlight.Build this circuit and prevent theft in your premises.

Working

The transmitter circuit is powered by 3V DC. The multi-vibrator built around NE555 timer (IC1) produces a frequency of 5.25KHz. The body of the laser torch is connected to the emitter of the NPN transistor SK100 (T1) and the spring-loaded lead protruding from inside the torch is connected to the ground.
The receiver circuit is powered by 12V DC. It uses the photo-Darlington 2N5777 (T2) to sense the laser beam transmitted from the laser torch. The output beam signals from the photo-Darlington are given to the two-stage amplifier followed by a switching circuit. As long as the laser beam falls on photo-Darlington T2, the 12V relay (RL1) remains unenergized and the buzzer does not sound. Also, the indicating LED (LED1) doesn’t glow.
When anyone interrupts the laser beam falling on photo-Darlington T2, NPN transistor BC547 (T6) stops conducting while NPN transistor SL100 (T7) is driven into conduction. As a result, LED1 glows and relay RL1 is energize to sound the buzzer for a few seconds (the alarm duration being determined by the values of resistors R15 and capacitor C10 in the circuit). At the same time, the large indication load (230V AC alarm or hooter for louder sounds or any other device for momentary indication) also gets activated as it is connected to 230V AC mains via normally opened (N/O) contact of relay RL1.

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Battery Low Indicator Save Rs. 75.00
Rs. 250.00
Rs. 175.00

Battery Low Indicator

Battery Low Indicator

by KNS Pvt Ltd
Save Rs. 75.00
Rs. 250.00
Rs. 175.00

The purpose of the battery low indicator is to give a visual indication when a battery has been discharged below a certain level. This is especially crucial for re-chargeable batteries that should not be discharged below a certain voltage level. This lower voltage limit depends upon the type of the battery. The battery low indicator circuit can be typically used for 12V batteries to give an indication of the battery voltage falling below the preset value. The indication is in the form of a flickering LED.

Learning from the project

  • Application of the LM319 dual comparator for level comparison.
  • Application of the NE555 timer in astable mode of operation.

Product description

The heart of the battery low indicator circuit is the dual comparator IC LM319 (denoted as IC1) which compares the battery’s voltage to a reference voltage level. Only one of the two independent comparators that are a part of the LM319 is used in the circuit. The two inputs to this comparator are:

  1. The reference voltage, which is applied to the non-inverting input pin (4). It is held constant at approximately 1.2V by the zener diode (D1).
  2. Battery’s voltage, which is applied via a potential divider arrangement built around resistors R2, R3, and preset VR1 and fed to the inverting input pin (5).

The corresponding output is generated at pin 12 of IC1. Preset VR1 is very important as it sets the voltage level at which a visual indication of the low battery level is generated. For example: If the battery under test is of 12 V and an indication is required as soon as the battery voltage falls below 10.5 V, the voltage at the inverting input (pin 5 of IC1) should be adjusted to 1.2 V using preset VR1.

Initially, when the battery is fully charged, the voltage at the inverting input (pin 5) of IC1 is higher than the non-inverting input (pin 4- voltage level held constant at approximately 1.2 V by D1). This causes the output at pin 12 of IC1 to remain low. The reset pin (pin 4) of an NE555 timer (IC2) is connected to the output pin of IC1 and hence, a low gets applied to it correspondingly. Since the reset pin is “active low”, the NE555 is reset continuously and oscillations are not generated at its output (pin 3). As a result, LED1 does not blink.

Considering the example values, when the battery voltage falls below 10.5 V, the voltage at the inverting input (pin 4) of IC1 becomes lower than the non-inverting input (pin 5) and the output at pin 12 of IC1 goes high. This applies a “high” to the connected reset pin of IC2 (NE555 timer) and the astable multi-vibrator built around IC2 starts generating oscillations. LED1 is connected to the output pin (pin 3) of IC2 and hence blinks to indicate low battery voltage and the battery needs to be charged before further use.

 

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Anti-Bag Snatching Alarm Save Rs. 100.00
Rs. 400.00
Rs. 300.00

Anti-Bag Snatching Alarm

Anti-Bag Snatching Alarm

by KNS Pvt Ltd
Save Rs. 100.00
Rs. 400.00
Rs. 300.00

This anti bag snatching alarm builds a circuit that is locked in a plug and socket arrangement in standby mode. The kit can be kept in a bag or suitcase, and simulates a police horn if someone attempts to snatch the bag. Thus, while traveling, this kit enables people to carry cash or valuables without fear. The alarm can be turned off only by the authorized person by using a hidden key.

Number of ICs used: 3

Learning from the project

*Application of the operational amplifier IC CA3140 as a comparator.
*Application of the NE555 timer IC in monostable mode.
*Use of the music generator IC UM3561.
*Use of transistors as signal amplifiers.

Product description

Build yourself an awesome anti bag snatching alarm and protect your luggage and travel care-free.

Circuit working

The circuit of the anti bag snatching alarm is designed around the operational amplifier CA3140 (IC1) configured as a comparator. The non-inverting input (pin3) of IC1 is kept at half the supply voltage (around 4.5V) by a potential divider resistor network. The inverting input (pin 2) of IC1 is kept low through the shorted plug at the socket. As a result, the voltage at the non-inverting input is higher than the inverting input and the output of IC1 is high.

The output from pin 6 of IC1 is fed to trigger pin 2 of IC NE555 (IC2) via a coupling capacitor. IC2 is configured in monostable mode. The trigger pin is held high by a resistor of 10 kilo-ohms. Normally, the output of IC2 remains low and the alarm is off. A resistor and a capacitor are connected to the reset pin of IC2 to prevent false triggering.

When there is a bag-snatching attempt, the plug connected to the circuit detaches. At this moment, the voltage at the inverting input of IC1 exceeds the voltage at the non-inverting input and subsequently, the output goes low. This sends a low pulse to trigger pin 2 of IC2 to make its output high. Consequently, the alarm circuit built around IC UM3561 (IC3) gets the supply voltage at pin 5.

Its output is fed to the base of single-stage transistor amplifier BD139 (T1) that amplifies the generated alarm signal. A loudspeaker is connected to the collector of T1 to produce the alarm. The alarm can be put off if the plug is inserted into the socket again.

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Variable Power Supply With Digital Control

Variable Power Supply With Digital Control

by KNS Pvt Ltd
Rs. 500.00

Summary

A Variable Power Supply with Digital Control is one of the most important and essential requirements in an electronics lab. The available power supply must provide variable outputs in steps. This circuit gives variable and fluctuation-free DC voltage as output in the range of 1.5V to 12V. No. of ICs used: 4

Learning

Things which you can learn:

*Application of the NE555 timer IC in the stable mode of operation.
*Application of the 3-terminal positive and negative voltage regulator ICs LM317 and LM7912 respectively.
*Use of the decade counter IC CD4017.
* Basics of Voltage and current control

Product Description

A variable power supply is a must for those who are looking forward to taking their project building to the next level. Armed with this system you can have a clean DC supply without spikes and it ranges from 1.5 V to 12 V. Get ready and build this kit and enjoy making projects.

Working:

The circuit of the Variable Power Supply with Digital Control is built around an adjustable 3-terminal positive voltage regulator IC LM317, CMOS decade counter IC CD4017, timer IC NE555 and 3-terminal fixed negative-voltage regulator LM7912. The AC mains supply is stepped down by transformer X1 to deliver a secondary output of 12V-0-12V AC, 1A. The output of the transformer is rectified by a full-wave rectifier comprising diodes D1 through D4.

Capacitors C1 through C4 are connected in parallel to rectifier diodes to bypass undesired spikes and provide smooth and fluctuation-free power. Capacitors C5 and C13 are used as filters to eliminate ripple. Here both negative and positive half cycles are used to obtain positive as well as negative DC output. LED1, along with current limiting resistor R1, is used for mains ‘on’ indication. Timer IC NE555 (IC1) is wired as an astable multi-vibrator. It generates clock pulses when switch S2 is pressed.

The output of IC1 is connected, via an RC network, to the clock input of counter IC CD4017 (IC2). IC CD4017 is a decade ring counter. Each of its ten outputs goes high one by one when a clock pulse is received. The outputs of IC CD4017 are connected to the bases of transistors T1 through T10, respectively. LED3 through LED11 is used here to indicate the voltage levels.

The collectors of transistors T2 through T10 are connected to presets VR1 through VR9, respectively, which are used to set the output voltage. Adjustable voltage regulator IC LM317 (IC4) develops 1.25V nominal reference voltage (VREF) between its output and the adjustable terminal. The reference voltage appears across resistor R16. When the voltage is constant, a constant current flows through one of the output-setting variable resistors (VRset, VR1 through VR9), giving an output voltage at pin 2 of IC4 as VOUT=1.25(1+VRset/R16). Presets VR1 through VR9 is adjusted to get the desired output voltage.

The collector of transistor T1 is directly connected to ADJ terminal (pin 1) of IC4, so the output voltage of IC4 will be the voltage across fixed resistor R16, which is equal to 1.25V. When switch S3 is pressed, pin3 of IC2 goes high and the output voltage becomes 1.2V. When switch S2 is pressed, the output of IC1 goes high.

As a result, the outputs of IC2 go high one by one as a ring counter. Since presets VR1 through VR9 are connected at the collectors of transistors T2 through T10, respectively, different output resistances appear between the adjustable and ground terminals of IC4, resulting in different output voltages. By using a properly calibrated digital multimeter you can easily adjust the presets to obtain 1.5V to 12V. A fixed, negative 12V DC can be obtained by using fixed, the negative-voltage regulator IC LM7912 (IC3). Thus the power supply unit can be used for circuits requiring both negative and positive DC voltages. When CD4017 is reset by pressing switch S3, the output voltage becomes 1.2V and all the voltage-indication LEDs turn off.

 

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Sound Operated Timer

Sound Operated Timer

by KNS Pvt Ltd
Rs. 250.00

Summary

The Sound Operated Timer is a multi-purpose electronic switch that can be used in a number of applications. The switch gets activated by the sound of a clap when clapping is done in front of a condenser mike. This turns on the appliance connected to the relay for a specified time period, after which it is automatically turned off. No. of ICs used: 1.

Product Description

The heart of the Sound Operated Timer is the NE555 timer IC (IC1) which is being operated in the monostable mode. The condenser mike converts the incoming sound signal to electrical variations that are amplified by transistor BC149. Resistors (R1-R4) and a capacitor (C1) provides proper biasing conditions for working of T1 in the active region. The amplified signals are effectively passed by capacitor C2 to trigger input pin (pin2) of IC1. This results in momentarily pulling pin2 to a low level whenever you clap in front of the mike. IC1 generated a rectangular pulse of time duration Tm at its output pin (pin3). This time duration is decided by values of preset VR1, resistors R7, R8 and capacitor C3. Thus relay RL1 at output remains energized for this specific time duration. Rotating the preset VR1 clockwise will increase this time while rotating it in an anti-clockwise manner will result in opposite effect. Diodes D1 and D2 are used as free wheeling diodes and help in proper functioning of the relay.

Learning

Application of the NE555 timer in the monostable mode.
Use of relays for appliance switching.

PC Based Automatic Time Manager

PC Based Automatic Time Manager

by KNS Pvt Ltd
Rs. 450.00

Summary

The PC based Automatic Time Manager can be used for controlling a school bell or a scheduled shift-timing alarm of a factory automatically.The load connected to the output can be an electric bell or a hooter.The timing can be programmed for everyday schedule as per individual requirement.The software has been developed using Microsoft Visual Basic and interfaced through PCs parallel port. No. of ICs used: 3

Learning

Things which you can learn:

*Application of the LM555 timer IC in the monostable mode of operation.
*Application of the optocoupler IC MCT2E.
*Interfacing software with hardware through PCs parallel port.
*Microsoft visual basic programming
*ATM Win Installer

Product Description

The PC based Automatic Time Manager uses a Windows-based program developed in Microsoft Visual Basic programming language to control an electric bell or hooter through an electromagnetic relay. The graphics have been included so that the master clock shows the real clock time on the PC’s screen. At the same time, it shows alarm clock timing for triggering the timer circuit for activating the bell or hooter.

Working:

The alarm timings, ‘on’/’off’ controls and their activation sequence can be set by the user as per his requirement through 48 numbers of settings—that is, 24 settings for alarm time display on the screen and 24 for enabling or disabling the timer circuit. The alarm time as well as bell or hooter ‘on’/’off’ timer can be set by simply clicking the bigger rectangular box and a small square box on the top of the rectangular box, respectively.


In PC-based Automatic Time Manager circuit, only two pins (namely, pin 2 and ground pin) of the parallel port are being used. Pin 2 corresponds to the first data bit ‘D0’ in 8-bit data bus of the parallel port. IC MCT2E isolates the PC from the main interfacing unit in case any short-circuit occurs. Thus, it acts as a safety device and protects the PC. IC LM555 (IC2) timer is configured in a monostable mode of operation. A low transition at its pin 2 will trigger the timer. IC2 timer can be triggered only if the alarm time is set to ‘1’ in enable condition in the software.

If the alarm time is set to enable condition, you will get a one-second long beep sound from the PC’s speaker and a high pulse at pin 2 of the parallel port of the PC. A high pulse output at pin 2 of the LPT port will cause momentary glowing of signal LED2 and conduction of transistor inside optocoupler IC MCT2E. The conduction of this transistor sends a low pulse to pin 2 of 555 timer IC2.

When timer IC2 gets triggered, its output pin 3 goes high and holds the relay for 30 seconds. Output pin 3 of timer IC2 is connected to relay driver BC547. The load is controlled through the relay contacts to switch ‘on’ or ‘off.’

The load-’on’ time duration can be set through a 100-kilo-ohm potentiometer (VR1) upto 60 seconds or more. The load (school bell or hooter) is connected to the pole of the relay. When the relay energises, the pole comes in contact with the N/O, and connects 230V AC across the load. This turns on the load for a brief predetermined time set through 555 timer circuit.

 


Software Interface:

Upon connection of the male connector pin 2 (D0) and ground (pins 18 through 25) to up tole connector on the PC, the ‘ATMINSTALL.zip’ file provided in the CD needs to be unzipped, to get a folder name ATM-Win-Installer. In this folder, a setup program is available and upon clicking the ‘setup’ file, this project will automatically install in ‘Program Files’ folder of Windows with the name ‘Project1’ folder along with other relevant files and drivers.

Electronic Watch Dog Save Rs. 50.00
Rs. 300.00
Rs. 250.00

Electronic Watch Dog

Electronic Watch Dog

by KNS Pvt Ltd
Save Rs. 50.00
Rs. 300.00
Rs. 250.00

Summary

The Electronic Watch Dog produces an alarm sound when a person crosses the gate. The circuit comprises a transmitter unit and a receiver unit, which are mounted face to face on opposite pillars/walls of the gate such that the IR beam gets interrupted when someone is standing at the gate or passing through it. When such a condition is detected, an alarm sound is generated for audible indication. No. of ICs used: 3

Learning

Things which you can learn:

*Application of IR transmitter and receiver.
*Application of the NE555 timer in the astable mode of operation.

Product Description

A simple circuit which acts as a Watch dog, informing the house owners about the forced or unauthorized entry.

Working

The transmitter end of the Electronic Watch Dog is built around the NE555 timer (IC1) which is wired as an astable multi-vibrator producing a frequency of about 38 kHz. The infrared (IR) beam is transmitted through IR LED1.

The receiver end of the circuit comprises of an IR sensor TSOP1738 (IR RX1), NPN transistor BC548 (T1), NE555 timer (IC2) and some resistors and capacitors. IC2 is wired as a monostable multi-vibrator with a time period of around 30 seconds. The melody generator section is built around the melody generator IC UM66 (IC3), transistor T2 and loudspeaker LS1. The transmitter and receiver units are aligned such that the IR beam falls directly on the IR sensor. As long as IR beam falls on the sensor, its output remains low, transistor T1 does not conduct and trigger pin2 of IC2 remains high. When anyone interrupts the IR beam falling on the sensor, its output goes high to drive transistor T1 into conduction and pin 2 of IC2 goes low momentarily. As a result, IC2 gets triggered and its pin3 goes high to supply 3.3V to melody generator IC3 at its pin 2, which produces a sweet melody through the speaker fitted inside the house. Output pin 3 of IC2 remains high for around 30 seconds. To achieve a high directionality of the IR beam towards the sensor, use a reflector behind the IR LED.

After both the units have been built, connect the 6V power supply to the receiver circuit. You should hear a continuous melody from the speaker. Now connect 6V power to the transmitter also and orient IR LED1 towards IR receiver. The melody should stop after about 30 seconds.Now the transmitter and the receiver units are ready for use. When somebody enters through the door, the IR beam is interrupted and the alarm sounds for 30 seconds. The alarm keeps sounding as long as one stands between the transmitter and receiver units. Using preset VR1, you can set the volume of the loudspeaker.

 

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