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!
PC based timer Save Rs. 50.00
Rs. 300.00
Rs. 250.00

PC based timer

PC based timer

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

Summary

Timers are very useful both for industrial applications and household appliances. The PC Based Timer circuit interfaces with a computer through a D25 pin male connector to switch ON/OFF a device for a particular time interval. The program of the PC Based Timer is written in C language & compiled using the Turbo C compiler. The maximum timing for which the circuit can operate a device is 18 hours. No. of ICs used: 1

Learning

Things which you will learn :

*Application of the optocoupler IC MCT2E.
*Application of the NPN transistor for switching.
*Application of diodes for freewheeling/flyback.

Product Description

The PC Based Timer uses a simple program and interface circuit to switch on/off the appliance via the relay circuit. The circuit is interfaced with the PC with a D25 pin male connector.

Working


The circuit uses the IC MCT2E(optocoupler) which isolates the PC and the relay driver circuits. The MCT2E prevents the PC from any short circuit that may occur in the relay driver circuit or appliance. The glowing of a red LED in the circuit indicates that the appliance is turned on while the NPN transistor BC548 is used as the relay driver.

The program code is written in ‘C’ language and compiled using ‘Turbo C’ compiler. When the program is run, it prompts the user to input the time duration in seconds or minutes to control the appliance.

Click To View Circuit Diagram

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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.

Secured Room Access System Save Rs. 151.00
Rs. 1,500.00
Rs. 1,349.00

Secured Room Access System

Secured Room Access System

by KNS Pvt Ltd
Save Rs. 151.00
Rs. 1,500.00
Rs. 1,349.00

Summary

Gone are the olden days where you have to have a key to open and access a room. Now no more, build yourself a cool digital secured room access system and enter into a new dimension.

The Secured Room Access System is a micro-controller based digital access control system that allows only authorized persons to access a restricted area/room. The system demands a password from the user trying to gain entry into a restricted area/room. When someone attempts to gain entry to the restricted area/room by guessing the correct password and continuously entering invalid passwords, the system locks its operation and can be unlocked only by the master user. No. of ICs used: 3

Learning

Things which you can learn :
*Learn interfacing of keypad matrix with the ATmega 8535.
*Learn interfacing of LCD module with micro-controller output.
*Use of relays to drive loads.

Product Description

The Secured Room Access System comprises of a small electronic unit with a numeric keypad, which is fixed outside the entry door to control a solenoid-operated lock. When an authorized person enters a predetermined number (or set password) via the keypad, the relay energizes for a limited time period and unlocks the solenoid-operated door lock. At the end of the preset delay, the relay de-energizes and the door gets locked again.

Working

The system uses a compact circuit built around the ATmega8535. A switch (S3) is used to reset the system, which is accessible only to the master user. Port D (PD0 through PD7) of the Atmega8535 is interfaced with the numeric keypad. Port C is interfaced with a 16-x2-line LCD. Four pins (PC4 through PC7) of Port C are used as data lines for the LCD module and three lines (PC0 through PC2) are used for controlling the LCD. Pin 40 of port A is connected to the relay driver circuit through optocoupler MCT2E (IC3) and transistor T1.

When port pin PA0 goes high, the internal transistor of IC3 drives transistor T1 into saturation and relay RL1 energizes. As the solenoid valve is connected through normally-closed (N/C) contact of the relay, the solenoid coil de-energizes and the gate is locked. A 16-key numeric keypad for password entry is connected to the micro-controller. The keypad is also used for password change and application of master password when required. The keypad is arranged in a 4x4 matrix. There are four scan lines/pins, which are set in output mode, and four sense keys, which are used as input lines to the micro-controller. At a small time interval, the micro-controller sets one of the four scan lines as low and the other three scan lines as high.

Then it checks for the status of sense lines one by one at the intersection of a specific scan line and sense line to find out if any key has been pressed. Similarly, after a small time interval, the next scan line is made low and remaining three scan lines are taken high, and again all three sense lines are checked for low level. This way the micro-controller checks which of the 16 keys is pressed. Due to the high speed of the micro-controller, the status of different keys is checked in less than 100 ms and a key press is detected and identified. As the keys are pressed manually by the user, this delay of 100 ms is not noticeable.

When a person wants to enter the room, he enters the 6-digit password, say ‘123456.’ If the password matches successfully, the gate is unlocked for 15 seconds. If you want to change the user password (123456) and enter the master password ‘291279,’ the system will ask you to change the user password. On successfully entering the password, pin A0 of port A becomes high for 15 seconds, because of which transistor T1 starts conducting through the emitter of the optocoupler and the relay energizes. The connection between the solenoid lock and the power supply is broken and the door is unlocked for 15 seconds.

Click To View Circuit Diagram

Click here to Download PDF