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!
School/College Quiz Buzzer Save Rs. 200.00
Rs. 750.00
Rs. 550.00

School/College Quiz Buzzer

School/College Quiz Buzzer

by KNS Pvt Ltd
Save Rs. 200.00
Rs. 750.00
Rs. 550.00

Summary

Manual buzzers used for quiz competitions in schools and colleges create a lot of confusion in identifying the first respondent. Although there are circuits using PCs and discrete ICs, they are either too expensive or limited to only a few number of players. The School/College Buzzer is a circuit that can be used for up to eight players.It uses the IC 74LS373 (which is an octal latch) and a few passive components to implement the quiz buzzer mechanism.

Learning

Things Which you will learn:
*Application of the octal latch IC 74LS3737.
*Use of SCRs in logic circuits.
*Application of transistors as switches.

Product Description

Quiz competition is an integral part of our learning and as the world advances towards technological advancement, there should be some changes in the way we conduct a quiz. So with this kit, you can build yourself a digital quiz buzzer supporting upto eight players and enjoy playing quiz without any confusion.

 

Working

At the heart of the School/College, Quiz Buzzer is the IC 74LS373 which transfers the logic state at data input pins (D0 through D7) to the corresponding outputs (Q0 through Q7). Data pins D0 through D7 are normally pulled low by resistors. One terminal of eight push-to-on switches (S1 through S8) is connected to +5V, while the other terminal is connected to the respective data input pins. The switches are to be extended to the players through cord wire.

The torch bulbs (BL1 through BL8) can be housed in boxes with the front side of the boxes covered with a white paper having the name or number of the contestant written over it for easy identification. When the power is switched on using switch S9 (provided terminals ‘A’ and ‘B’ of both the power supply and quiz buzzer sections are interconnected), the circuit is ready to be used.

Now all the switches (S1 through S8) are open and Q0 through Q7 outputs of IC 74LS373 (IC2) are low. As a result, the gates of silicon-controlled rectifiers (SCR1 through SCR8) are also low. As soon as a contestant momentarily presses his respective switch, the corresponding output data pin goes high.

This triggers the corresponding SCR and the respective bulb glows. At the same time, the piezoelectric buzzer (PZ1) sounds as transistor BC548 (T1) conducts. Simultaneously, the base of transistor BC548 (T2) becomes high to make it conduct. Latch-enable (LE) pin 11 of IC2 is tied to ground to latch all the Q0 through Q7 outputs. This restricts further change in the output state due to any change in the state of switches S1 through S8 by any other contestant.

Only one of the eight torch bulbs glows until the circuit is reset by on/off switch S9.

 

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Remote Control for Home Appliances Save Rs. 50.00

Remote Control for Home Appliances

by KNS Pvt Ltd
Save Rs. 50.00
Rs. 325.00
Rs. 275.00

Summary

The Remote Control for Home Appliances can be used to switch ON and OFF any home appliance or electrical device with a single press of a TV/VCR/DVD remote control. This low-cost circuit is based on the CD4017 counter IC which receives trigger pulse from the IR sensor and switches ON the relay, through which electrical devices are switched ON. Upon receiving the 2nd pulse the device is switched OFF.

Get ready to control your home appliances from your TV Remote control and upgrade your home to a techie Palace!!

Learning

Things which you can learn:
*Application of the IR transmitter and receiver modules.
*Application of the decade counter IC CD4017.
*Use of relays to drive loads.
*Applications of Transistors as amplifiers

Product Description

The Remote Control for Home Appliances can be connected to many home appliances such as lamps, fans, radios, etc to make the appliance switch ON/OFF from a TV, VCR or DVD remote control. This circuit can be operated from upto 10 meters.

Working


The 38kHz infrared (IR) rays generated by the remote control are received by IR receiver module TSOP1738 of the circuit. The output signal (from pin3) is amplified by transistor T1 (BC558). This amplified signal is fed to the clock pin (pin no.14) of decade counter IC CD4017 (IC1), pin 3 of which is connected to a red LED (LED1). This LED glows to indicate that the appliance is OFF. The output (pin no.2) of IC1 is connected to a green LED (LED2) and is used to indicate the ON state of the appliance. Transistor BC548 (T2) is connected to pin 2 of IC1 and drives the relay RL1.

The appliance to be controlled is connected between the pole of the relay and neutral terminal of mains. It gets connected to live terminal of AC mains via normally opened (N/O) contact when the relay energizes.

Click To View Circuit Diagram

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Moisture Monitor For Plants Save Rs. 50.00
Rs. 300.00
Rs. 250.00

Moisture Monitor For Plants

Moisture Monitor For Plants

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

Summary

The circuit is based on CD4060 14 Stage binary ripple counter which provides a frequency at pin 7 of the CD4060 which is decreased at pin 4 and gives a train of pulses for the transistor to switch the buzzer

Learning

CD4060 is a ripple counter IC which is widely used in digital electronics and this circuit teaches a concept which can be used to innovate new circuits based on CD4060

Product Description

Over-watering and under watering both are harmful to plants. Roots need air as well as water. If the soil is constantly saturated, air cannot reach the roots and they suffocate. Also, excess water weakens the plant and makes it susceptible to various diseases, particularly fungal attacks. Underwatering, on the other hand, is equally harmful. Plants not receiving enough water drop from the top down and leaf edges turn brown. Moisture monitor provides a solution to the above problem by monitoring the moisture level of the soil and producing an audio visual alert when the moisture goes below a preset level, indicating that the plant needs to be watered.

Click To View Circuit Diagram

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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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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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Automatic Room Light Controller with Visitor Counter Save Rs. 301.00

Automatic Room Light Controller with Visitor Counter

by KNS Pvt Ltd
Save Rs. 301.00
Rs. 3,300.00
Rs. 2,999.00

This automatic room light controller project with visitor counter is a reliable circuit based on the AT89S52 microcontroller. It takes over the task of controlling room lights as well us counting the number of people in a room accurately. When somebody enters a room, the counter is incremented by one and the light in the room is switched 'ON' and when any one leaves the room, the counter is decremented by one. Light is only switched 'OFF' when all the people in the room go out.

The total number of people inside the room is also displayed on the seven segment display by the microcontroller. It receives signals from the sensors, and this signal is operated under the control of software stored in ROM. Microcontroller AT89S52 continuously monitors the Infrared receivers. When any object passes through IR receivers, the IR rays falling on the receivers are obstructed, this obstruction is sensed by the microcontroller

Brand: HBeonLabs, Product assembled by: HBeonLabs

 

 

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