Top Grabbed

These are the products that hobbyists around you are buying the most. There must be something really, really good about them...
Design Your Own LI-FI Dongle And Speaker Save Rs. 60.00

Design Your Own LI-FI Dongle And Speaker

by KNS Pvt Ltd
Save Rs. 60.00
Rs. 400.00
Rs. 340.00

Summary

Light Fidelity (Li-Fi) is a new paradigm in wireless communication. In this project, you can learn to design a Li-Fi dongle (transmitter) and speaker (receiver) for audio and music applications. The proposed system is a replacement for wired speakers that play audio signals received through the light.

Product Description

How It works?

1. The LED light in a room is used not just to light up the room but also to play music, thus giving benefits of both the worlds. Also, LED bulbs use 85 per cent less energy than
incandescent bulbs and last up to 20 times longer, whereas the majority of Bluetooth modules are battery powered and generally last a year or two only before they need replacement. Hence the proposed system is energyefficient over Bluetooth version.

2. You can receive Li-Fi data as long as you are in the range of the light being emitted by the LED light source. Hence, the range depends on the strength of the light being emitted.

3. Connectivity needs to be established between the Bluetooth transmitter and the receiver, whereas with Li-Fi any user can receive data and play music on his speaker by simply keeping the receiver in the range of LED light source.

4. The proposed system can be used with any audio system by just connecting the Li-Fi dongle to its audio output jack, with no pairing and connectivity requests. This overcomes the problem of connecting a Bluetooth speaker to audio systems that do not have USB port and Bluetooth support, which is otherwise a tougher task.

5. The proposed Li-Fi dongle and speaker costs lower than a Bluetooth dongle and speaker. It uses a Li-Fi dongle to transmit audio signals from a source such as mobile phone, and a Li-Fi speaker with solar cells at the receiver end to receive audio signals without wires. The proposed Li-Fi dongle is connected to the audio jack output available on mobile phones. It has an LED through which audio/music signals are transmitted as light signals. These light signals are captured by the Li-Fi speaker through the solar cell array.

Door Guard Save Rs. 50.00
Rs. 300.00
Rs. 250.00

Door Guard

Door Guard

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

Thieves often target locked houses. This door guard circuit detects any vibration in its vicinity when somebody tries to break open the door. A simple circuit to protect all your valuable things.

Learning from this project

Things which you can learn:

  • Application of UM3561 IC.
  • Working of the transistor as an amplifier.
  • Working of MOSFET BS170.
  • Application of piezoelectric sensor.

Product Description

This is a simple door guard circuit which is based on piezo electric sensor to detect changes in the vibration caused due to the opening of doors.

Project working

The heart of the circuit is the piezo transducer (PZ1), which is the sensor element. If anyone attempts to open the door, the piezo element vibrates and the developed voltage drives transistors T1 and T2 into conduction. Then the alarm sounds for 20 seconds, which is taken care of by MOSFET T3 along with capacitor C1 and resistor R4 wired as a monostable timer.

 

Click here to Download PDF

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

Click here to Download PDF

Burglar Alarm Save Rs. 25.00
Rs. 150.00
Rs. 125.00

Burglar Alarm

Burglar Alarm

by KNS Pvt Ltd
Save Rs. 25.00
Rs. 150.00
Rs. 125.00

Summary

The burglar alarm implemented here is a simple circuit that automatically sounds an alarm whenever an intrusion is detected. 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 and this causes the loudspeaker to generate a continuous and loud alarm sound. Once the loop is broken, the alarm can only be silenced by either turning OFF the power supply or by replacing the broken wire by a new continuous loop. Number of ICs used: None

Learning

Things which you can learn:

*Operation of transistors (both NPN and PNP type) in different modes, especially in conduction and cut-off mode.
*Two stage amplifier with feedback.

Product Description

The Burglar Alarm circuit employs a simple mechanism to sound an alarm when an intrusion is detected. If the loop is broken then an intrusion is detected and the alarm is sounded.

Working

It consists of an oscillator section which is merely a two-stage amplifier with feedback. This amplifier is implemented with the help of two transistors (T1 is an NPN transistor-BC548 while T2 is a PNP transistor-SK100) connected in a feedback arrangement to generate oscillations. Transistor T1 is responsible for generating oscillations while transistor T2 (connected to the base of T1) amplifies these oscillations in order to drive the loudspeaker for sounding the alarm.

Consider the following cases:

1. Secure Premises: The connection of the two transistors is such that the base of T1 is normally shorted to the ground and that it remains in the cut-off mode when the sensing loop is intact. Due to the absence of the base current in T1 in this mode, there are no oscillations and hence, the loudspeaker does not generate the alarm sound. This indicates that no intrusion has taken place.

2. Intrusion: When the loop is broken by an intruder or a burglar, the base of transistor T1 becomes open and oscillations are generated at its collector. As the base of T2 is connected to the collector of T1, the oscillations are amplified by it and further fed back to its emitter (via the path along capacitor C1 and resistors R1, R2). The loudspeaker obtains this amplified signal from the collector of transistor T2 and converts it into audible alarm sound. This indicates the occurrence of an intrusion/break-in.

As both the transistors are silicon type, the current drawn by the circuit is very low even in the alert mode.

 

Click here to Download PDF

 

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.

Click To View Circuit Diagram

Click here to Download PDF

Power Failure And Resumption Alarm Save Rs. 100.00

Power Failure And Resumption Alarm

by KNS Pvt Ltd
Save Rs. 100.00
Rs. 300.00
Rs. 200.00

Summary

The Power Failure and Resumption Alarm circuit sounds an alarm whenever AC supply mains fails or resumes. The circuit gives an audio-visual indication of the failure and resumption of mains power through a bi-colour LED and a piezoelectric buzzer. No. of IC used: 3

Learning

Thiings Which you can learn:
*Application of the LM556 dual timer IC in the astable and monostable mode.
*Application of PNP and NPN transistors.
*Concept and working of bi-colour LEDs.

Product Description

A simple circuit which provides Audio Visual Indication when the AC supply resumes/fails.
This is important as when the users gets informed about the power failure, he/she can judiciously use the supply from the inverter so that they are not affected due to excessive drain of battery.The heart of the Power Failure and Resumption Alarm circuit is the dual timer IC LM556. When mains is present, the bicolour LED (LED1) glows in green colour while when the mains fails it turns red.

Working:

When mains is present, the PNP transistor BC558 (T1) is in the cut-off state and therefore the bicolour LED glows in green colour. When power fails, PNP transistor T1 starts conducting and bicolour LED glows in red colour. Due to non-availability of Vcc voltage at pin 14 of LM556 (IC2), its output pin (Pin9) remains low and NPN transistor BC548 (T3) does not conduct.

However, a 4700µF capacitor (C7) holds an adequate charge and hence PNP transistor BC557 (T4) conducts and the piezoelectric buzzer (PZ1) sounds continuously for approx. eleven seconds until capacitor C7 discharges completely. When power resumes, bicolour LED glows in green colour and the buzzer beeps for approx. 14 secs.

IC LM556 outputs frequencies in the form of pulses at its pin 9. These pulses are coupled to the NPN transistor BC548 (T3), which conducts and cuts off depending on the output at pin 9 of IC2. A Red LED (LED2) is connected to pin 9 via a 270-ohm current-limiting resistor (R7) to indicate power resumption.

 

Click here to Download PDF

 

Intruder Alarm Save Rs. 75.00
Rs. 250.00
Rs. 175.00

Intruder Alarm

Intruder Alarm

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

Summary

The Intruder Alarm automatically activates a loud alarm whenever any unauthorized entry is attempted. Unlike other alarms, the Intruder Alarm circuitry does not need replacement of a broken loop. The alarm can be turned OFF just by the simple flick of a switch. The unit power on indication by LED is also provided here for better monitoring.
Build yourself a simple intruder alarm circuit to keep the thieves at bay!! No. of ICs used: 2

Learning

Things which you will Learn :
*Learn how to use LDR sensor.
*Application of basic gates and flip-flop and hex inverters.

Product Description

The Intruder Alarm circuit should be typically fitted to the door of your house, to sound an alarm when anyone pushes the door. This way it alarms you against thieves or intruders. The circuit primarily comprises a transmitter and receiver pair. The transmitter is fitted onto the inside of the door frame while the receiver is fitted to the door panel.

Working:

The transmitter section consists of a laser diode which is powered by a 9V battery. When the switch (S1) in the transmitter section is closed, the laser diode glows. Closing switch (S2) provides power supply to the receiver section. Light falling from the laser diode on the light-dependent resistor (LDR) in the receiver section provides base current to transistor T1 and it starts conducting. This grounds the base of the transistor (T2), so it doesn’t conduct and the alarm remains off. When somebody pushes the door, light incident on the LDR is interrupted and the transistor (T1) stops conducting since the LDR offers a high resistance in the absence of light. Transistor T2 receives base current and starts conducting. The pulse from the emitter of transistor T2 is connected to the inputs of AND gate N1 (IC1). The high output of AND gate is connected to a JK flip-flop (IC2) that works as a latch. As a result, output pin 12 (Q1) of IC2 goes high to cause conduction of transistor T3 and consequent sounding of the alarm. The alarm can be turned off by switch S2.

Note: While testing at EFY Lab, a laser torch was used in place of the transmitter.

Click To View Circuit Diagram

 

Click here to Download PDF

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.

 

Click here to Download PDF