Constructional Timer Projects

                                        

Timer circuit has been used in many projects and there are basically 2 types that are used these days. One of them is the use of analog RC circuit where charging of the capacitor circuit determined the T of the circuitry. This type of circuitry has larger tolerance and is used in applications where the T is not so critical as the T is affected by the tolerance of the RC components used.

The other is the use of crystal or ceramic resonators together with microprocessor, microcontroller or application specific integrated circuit that need higher precision T in the tolerance of up to 5 ppm (parts per million).

555 IC

One commonly used circuit is the 555 IC which is a highly stable controller capable of producing timing pulses. With a monostable operation, the T(time) delay is controlled by one external resistor and one capacitor. With an astable operation, the frequency and duty cycle are accurately controlled by two external resistors and one capacitor.The application of this integrated circuit is in the areas of PRECISION TIMING, PULSE GENERATION, TIMING DELAY GENERATION and SEQUENTIAL TIMING.

A typical 555 IC block diagram is as shown below.

Monostable Operation

Figure below shows the monostable operation of a 555 IC.

In this mode, the device generates a fixed pulse whenever the trigger voltage falls below Vcc/3. When the trigger pulse voltage applied to pin 2 falls below Vcc/3 while the its output is low, its internal flip-flop turns the discharging transistor Tr off and causes the output to become high by charging the external capacitor C1 and setting the flip-flop output at the same instant. The voltage across the external capacitor C1, VC1 increases exponentially with the T constant T=R_A*C1 and reaches 2Vcc/3 at td=1.1R_A*C1. Hence, capacitor C1 is charged through resistor R_A. The greater the time constant R_A*C1, the longer it takes for the VC1 to reach 2Vcc/3. In other words, the time constant R_A*C1 controls the output pulse width. When the applied voltage to the capacitor C1 reaches 2Vcc/3, the comparator on the trigger terminal resets the flip-flop, turning the discharging transistor Tr on. At this time, C1 begins to discharge and its output goes to low.

Astable Operation 

An astable operation is achieved by configuring the circuit as shown above. In the astable operation, the trigger terminal and the threshold terminal are connected so that a self-trigger is formed, operating as a multivibrator. When its output is high, its internal discharging transistor Tr turns off and the VC1 increases by exponential function with the time constant (R_A+R_B)*C. When the VC1, or the threshold voltage, reaches 2Vcc/3, the comparator output on the trigger terminal becomes high, resetting the F/F and causing its output to become low. This in turn turns on the discharging transistor Tr and the C1 discharges through the discharging channel formed by RB and the discharging transistor Tr. When the VC1 falls below Vcc/3, the comparator output on the trigger terminal becomes high and the tmr. output becomes high again. The discharging transistor Tr turns off and the VC1 rises again. The frequency of oscillation is given as below. 

Frequency, f = 1/T = 1.44/[(R_A + 2R_B)C1]

Thanks & Regarded

  Nipul Prajapati

How to :Find Facebook password

Now its easy to decrypt facebook password using FacebookPasswordDecryptor tool .

About FacebookPasswordDecryptor:

FacebookPasswordDecryptor is the FREE tool to instantly recover stored Facebook account passwords stored by popular web browsers and messengers. Most of the applications  store the Login passwords to prevent hassale of entering the password everytime by the user. Often these applications use their own proprietary encryption mechanism to store the login passwords including Facebook account passwords. FacebookPasswordDecryptor automatically crawls through each of these applications and instantly recovers the encrypted Facebook account password.FacebookPasswordDecryptor is fully portable tool which can be directly run anywhere without installing locally. It also comes with Installer for those who wants to install it locally and use it on regular basis. It works on wide range of platforms starting from Windows XP to latest operating system Windows 7.

Features :

• Instantly decrypt and recover stored encrypted Facebook account password from Popular Web browsers and Messengers.
• Support recovering multiple Facebook accounts stored with any of the supported applications.
• Automatically discovers the supported applications from their respective install location and recovers the password instantly.
• Sort feature to arrange the displayed password list by username and password which makes it easy to search through 100′s of entries.
• Save the recovered Facebook password list to HTML/TEXT file for transferring to other system or for future use.
• Easier and faster to use with its enhanced user friendly interface.
• Completely Portable Tool which also comes with optional Installer for assisting you in local Installation & Uninstallation.

                            

 

    Thanks & Regarded

      Nipul Prajapati

           

                 

Wireless Hacking

              

                                              

   

Nowadays, there are wireless hotspots everywhere! You can get internet access with a wireless enabled laptop almost everywhere you go. In this chapter I will discuss ways a hacker goes about getting into secure wireless networks and things he can do once he is inside.
Scanning for Wireless Networks
For this section and the following, you will need to have a wireless card/adapter. The hacker starts by scanning for wireless networks near him. The Windows tool we will use in this section is called NetStumbler. Also by the time you receive this eBook MacStumbler may already be released for those of you using a Mac.

Some other similar programs are:
• Kismet for Windows and Linux.
• KisMac for the Mac.
1. Download and install NetStumbler.
2. Run it. It automatically starts to scan for wireless access points.
3. Once it is completed, you should see a list of all the wireless access points around you.
4. If you click on the MAC address of one of the discovered wireless networks under channels, you will see a graph that shows the wireless network’s signal strength. The more green and the less spaces, the better the signal.
5. As you can see NetStumbler provides a lot more than just the name (SSID) of the wireless network. It provides the MAC address, Channel number, encryption type, and a bunch more. All of these come in use when a hacker decides he wants to get in the secured network by cracking the encryption. The most common types of encryption are:
• WEP (Wired Equivalent Privacy) – WEP isn’t considered safe anymore. Many flaws have been discovered that allow a hacker to crack a WEP key easily.
• WAP (Wireless Application Protocol) – WAP is the currently the most secure and best option to secure your wireless network. It’s not as easily cracked as WEP because the only way to retrieve a WAP key is to use a brute-force or dictionary attack. If your key is secure enough, a dictionary attack won’t work and it could take decades to crack it if you brute-force it. This is why most hackers don’t even bother.

Cracking WEP
In this section we will use be using the Live Linux distribution called BackTrack to crack WEP. Backtrack comes with a huge list of preloaded software for this very purpose. Before we begin, there are a couple requirements:
1. You need a computer with a compatible wireless adapter.
2. Download Backtrack and create a Live CD.
The tools we will be using on Backtrack are:
• Kismet – a wireless network detector
• airodump – captures packets from a wireless router
• aireplay – forges ARP requests
• aircrack – decrypts the WEP keys
Let’s begin!
1. First we will find a wireless access point along with its bssid, essid and channel number. To do this we will run kismet by opening up the terminal and typing in kismet. It may ask you for the appropriate adapter which in my case is ath0. You can see your device’s name by typing in the command iwconfig.
2. To be able to do some of the later things, your wireless adapter must be put into monitor mode. Kismet automatically does this and as long as you keep it open, your wireless adapter will stay in monitor mode.
3. In kismet you will see the flags Y/N/0. Each one stands for a different type of encryption. In our case we will be looking for access points with the WEP encryption. Y=WEP N=OPEN 0=OTHER(usually WAP).
4. Once you find an access point, open a text document and paste in the networks broadcast name (essid), its mac address (bssid) and its channel number. To get the above information, use the arrow keys to select an access point and hit <ENTER> to get more information about it.
5. The next step is to start collecting data from the access point with airodump. Open up a new terminal and start airodump by typing in the command:
airodump-ng -c [channel#] -w [filename] –bssid [bssid] [device]
In the above command airodump-ng starts the program, the channel of your access point goes after -c , the file you wish to output the data goes after -w , and the MAC address of the access point goes after –bssid. The command ends with the device name. Make sure to leave out the brackets.
6. Leave the above running and open another terminal. Next we will generate some fake packets to the target access point so that the speed of the data output will increase. Put in the following command:
aireplay-ng -1 0 -a [bssid] -h 00:11:22:33:44:55:66 -e [essid] [device]
In the above command we are using the airplay-ng program. The -1 tells the program the specific attack we wish to use which in this case is fake authentication with the access point. The 0 cites the delay between attacks, -a is the MAC address of the target access point, -h is your wireless adapters MAC address, -e is the name (essid) of the target access point, and the command ends with the your wireless adapters device name.
7. Now, we will force the target access point to send out a huge amount of packets that we will be able to take advantage of by using them to attempt to crack the WEP key. Once the following command is executed, check your airodump-ng terminal and you should see the ARP packet count to start to increase. The command is:
aireplay-ng -3 -b [bssid] -h 00:11:22:33:44:5:66 [device]
In this command, the -3 tells the program the specific type of attack which in this case is packet injection, -b is the MAC address of the target access point, -h is your wireless adapters MAC address, and the wireless adapter device name goes at the end.
8. Once you have collected around 50k-500k packets, you may begin the attempt to break the WEP key. The command to begin the cracking process is:
aircrack-ng -a 1 -b [bssid] -n 128 [filename].ivs
In this command the -a 1 forces the program into the WEP attack mode, the -b is the targets MAC address, and the -n 128 tells the program the WEP key length. If you don’t know the -n , then leave it out. This should crack the WEP key within seconds. The more packets you capture, the bigger chance you have of cracking the WEP key.
With all the different computers and network adapters out there, you may come across a error occasionally. If you get stuck, remember, Google is your friend!  Search for an answer and I guarantee you that 99% of the time you will find a solution

Thanks & Regarded

 Nipul Prajapati