NCT - National Certificate in Technology: Choice and Hobby

Showing posts with label Choice and Hobby. Show all posts

Saturday, June 24, 2017

Smart Receptionist With Smartlock System

Kirish June 24, 2017 0 Choice and Hobby

Presented here is a security system that lets you see a visitor while EFY Tested your main office door is locked. If you are in the middle of a meeting in a conference room and there is a visitor at the door, this system will send a notification to your smartphone with a photo of the visitor as email. If you approve, you either use your mobile or PC to unlock the front door using a Web browser. Alternatively, if you have a door bell with intercom facility, you can talk to the visitor when he or she rings the door bell.

A typical block diagram of the smart receptionist with a smartlock system is shown in Fig. 1.

Fig. 1: Smart receptionist with a smartlock system

Circuit and working

Interfacing circuitry of the smart receptionist and lock system is shown in Fig. 2. Raspberry Pi runs on standard Raspbian Linux distribution with Wi-Fi dongle, GPIO library and software written in Python language. Raspberry Pi GPIO4, GPIO17 and GPIO25 are connected with resistors R3, R2 and R1, respectively, to make logic level low.

Door bell.

The door bell signal from CON3 is routed to GPIO17 pin on Raspberry Pi. When a visitor rings the door bell, the status LED glows and GPIO17 becomes high. Amplitude of the door bell signal output depends on the door bell/chime used. You can use a door bell that gives 3V signal.

Fig. 2: Circuit diagram of the smart receptionist with a smartlock system

Captured signal should not exceed Raspberry Pi’s 3.3V limit on GPIO pins. So a 3V zener (ZD1) is used in this circuit. Ground wire of the door bell circuitry should be connected to GND pin of Raspberry Pi and the anode of status LED to GPIO17.

When GPIO17 becomes high, the system captures the photo of the visitor through the webcam connected to Raspberby Pi through USB. Captured photo is sent to your email ID configured in your source program.

Open the attachment in your email and check the photo of the visitor. After your visitor is identified, either open the door directly or talk to him or her through an intercom if it is installed at the door.
Smartlock.

When status LED glows to indicate that the door bell is ringing, press Camera tab on your Web browser (Fig. 3). This will make GPIO25 pin of Raspberry Pi high, enabling the webcam to capture the photo of the visitor. Captured photo is sent to your email ID.

After your visitor is identified, you may open the door by pressing Lock tab on the Web browser. With Lock tab pressed, GPIO4 becomes high. Since relay driver transistor T2 is connected to GPIO4, T2 conducts and energises relay (RL1). This provides a 12V DC supply from CON2 to the solenoid lock connected at CON1, and the door opens.

Sourced By: EFY : Author: Biswajit Das was manager - R&D, EFY Labs till recently

Sunday, September 21, 2014

How to Made a Stune Gun at Home

Kirish September 21, 2014 0 Choice and Hobby

There seems to be alot of interest in making home made stun guns these days. Some things need to be said before we go any farther. Home made stun guns like any home made device could be hazardous! Home made devices are fun to build and play with, but use at your own riskI. If you doubt your skills, or need some thing more powerful and dependable, click on a link and have a look around

There is a huge difference between a Stun Gun and a Taser, a stun gun is a contact weapon and a taser fires darts attached to wires. We are Talking about a Stun Gun Here. If you want to learn more about a Taser but. If you are still wanting to build your own stun gun than lets get started.

Assembly of a home made stun gun

The main piece of equioment needed is a disposable camera, make sure it is one with a flash.

#1- carefully open the casing of the camera, but be careful not to damage anything in the process.

#2-Take out the battery to prevent being shocked in case of accidental discharge.

#3-You will need paper clips, that will need to be shortened and attached to each end of the Capacitor. These will act as the wires through which the shock will be emitted.

#4-Put the Battery back in ensuring that you don't touch the wires after it's back in.

#5-Press the flash button on the camera to charge and than use a screw driver to see the results.

essentually the main part of this project is adding wires ( in the form of paper clips ) to each end of the Capacitor.

There really isn't much more to it!

Stun Gun Schematics

This is diagram #1 of a working Stun Gun. You will have to be able to understand electrical circuit diagrams.

Self Made Stun Gun Electrical Diagram

This is another Stun Gun circuit diagram althoe a bit more complex. You will need the ability to read and understand electrical circuit diagrams to assemble a stun gun from these drawings.

Stun Gun Electronics Number Three

This is an even more complex drawing and will require you to have a good understanding of electronics and electrical diagrams to assemble. It should prove to be a challanging project for every one except someone in the Electronics field.

The Reality of self built Stun Guns

Just being able and willing to build a home made Stun Gun doesn't really mean that you actuaslly should.

People that construct home made stun guns have a tendency to want to test them on friends or family. Stun Guns home made or not are not toys and should never be treated as such.

There have been instances of home made stun guns blowing up in peoples hands and medical complications from being burned or shocked.

There is no way of telling what will happen with a home made device of this kind. Caution should always be first and the number one thought should be,

Should I even build the damb thing at all.

Well thats not for me to answer, because if you are determined you would have just found the information your self any way.

Sourced By: Circuitsproject

Friday, February 7, 2014

Simple Programmable Electronic Dice with Numeric Display

Kirish February 07, 2014 0 Choice and Hobby

Here’s a simple programmable electronic dice with numeric display. This dice can be programmed using a 4-way DIP switch to display any random number between ‘1’ and ‘2,’ ‘1’ and ‘3,’ ….. or ‘1’ and ‘9.’

To obtain the desired dice range, inner switches A, B, C and D of DIP switch are to be set as per the table. For example, if you want the electronic dice to count from 1 to 8, close switches A and D and keep B and C open. On pressing switch S1, the display varies fast between ‘1’ and ‘8.’ When you release S1, the display stops shuffling and the last (latest) number remains on it.

IC1 is a dual 4-input Schmitt trigger NAND gate 74LS13. Gate N1 is used as an oscillator built using resistor R2 and capacitor C1 to produce approximately 70kHz clock frequency, which is fed to IC2. Gate N2 loads data at the inputs of IC2.

IC2 is a presettable binary counter (74LS191) with parallel loading facility. Whenever its pin 11 goes low, the data present at its inputs D through A (which is ‘0001’) appears at its outputs QD through QA when all the inner switches of DIP switch are open and DIS1 shows the minimum count as ‘1’ (and not ‘0’).

Simple Programmable Electronic Dice Circuit Diagram

Simple Programmable Electronic Dice with Numeric Display

With inner switches of DIP switch in positions shown in the table, the count output can go from ‘0001’ to the maximum count shown under ‘Dice Range’ in the table when switch S1 is depressed. On releasing switch S1, the last count within the dice range gets displayed.

The outputs of IC2 are displayed on common-anode, 7-segment display LTS542 (DIS1). BCD-to-7-segment decoder IC 7447 (IC3) is used to drive the display. Resistor R8 limits the current through DIS1.

Author: Maneesh Chadha

PC-Based Candle Ignitor Circuit Diagram

Kirish February 07, 2014 0 Choice and Hobby

Here’s a PC-based lighting system that lets you light up a candle using matchsticks by just pressing the ‘Enter’ key on the PC’s keyboard. It is especially useful when celebrating such occasions as birthdays and anniversaries.

The number of matchsticks required to light up the candle is placed on the candle (alongside its wick) as shown in the figure. The heating coil for igniting the matchsticks is kept near them.

The interface circuitry between the PC and the heating coil for the candle-matchsticks arrangement comprises an inverter, monostable and relay driver. Transistor BC548 (T1) acts as the inverter, IC 555 (IC1) is configured as the monostable circuit and transistor SL100 (T2) is the relay driver.

When you press ‘Enter’ key on the keyboard, the inverted output at the collector of transistor T1 goes low to trigger IC1 through its pin 2. Output pin 3 of the monostable goes high and transistor T2 conducts for around 50 seconds.

PC-Based Candle Ignitor Circuit Diagram

The conduction of transistor T2 energises relay RL1, which, in turn, connects the heating coil to 230V AC through the normally opened (N/O) contact. In place of the heating coil, you can also use an electric cigarrette lighter. The heating coil becomes red hot when connected across the 230V AC and ignites the matchsticks. The flames of the matchsticks light up the candle.

The program, written in ‘C’ language, is simple and easy to understand. The parallel-port D-type female connector normally available on the back of the PC is used for outputting the data to the interfacing circuitry. The address 378H of parallel-port LPT1 is used in the program. The parallel-port pin 2 corresponding to data bit D0 sends the control signal to energise the relay, which, in turn, connects the load to AC mains.

This circuit uses only one output of the PC’s parallel port to light up the candle, but it can be extended to light up up to eight diyas/candles in thiruvillaku (as called in South India) by using eight outputs with a slight change in the program and adding seven similar circuits.