A SIMPLE GUIDE FOR YOU
November 3, 2011 at 5:50 pm
Separate stages are used to drive the two indicator LEDs, a dual operational amplifier being used to drive D1 and a 555 monostable driving D2. Figure 1 shows the circuit diagram of the CMOS Logic Probe.
Figure 1. Circuit Diagram of CMOS logic probe.
Both sections of IC1 are used as voltage comparators rather than operational amplifiers, and these each have one input connected to a reference voltage, and the other taken to the input of the probe. The unit must indicate a high input state if the input voltage is more than about 70% of the supply voltage, and allow input state if the input is at less than about 30% of the supply potential. R3 to R5 form a potential divider which gives reference voltages of approximately 30% and 70% of the supply voltage.
If the input is low, IC1a’s non-inverting input will be at a higher potential than the inverting input so that the output goes high and switches on D1b. IC1b has the opposite input states so that its output goes low and D1a is switched off. This gives a green indication from D1. With the input in the high state IC1a’s inverting input is taken to a higher voltage than the non-inverting input, causing the output to go low and switch off D1b. IC1b’s non-inverting input will now be at a higher voltage than the inverting input, causing IC1b’s output to go high and switch on D1a so that a red indication is obtained from D1.
If the input is between the two logic states the outputs of the two comparators will both assume the high state so that the red and green sections of D1 switch on to produce a yellow display. R1 and R2 bias the input between the two logic levels so that the unit will indicate a fault condition (with D1 in the yellow state) if the input is taken to an open circuit test point.
This section of the circuit does not enable the user to differentiate between a static level between the two logic states and a high frequency pulse signal, since the latter will cause both sections of D1 to switch on in turn and give the impression of a yellow display due to the switching action being too fast to be seen. This is overcome by applying the input signal to the trigger input of a 555 monostable. Normally R8 and R9 hold the input of IC2 above the trigger threshold, but if there IS a pulsing input signal it will be coupled to the input of IC2 by C1 and on negative transistions IC2 will be activated. LED indicator D2 is then switched on for about 0.25 seconds each time IC2 is triggered, but with a high frequency input signal the circuit will be retriggered almost as soon as each output pulse ceases, and D2 will appear to light continuously. C1 blocks steady state inputs so that IC2 is not triggered, except possibly for a single triggering when the input is taken to a new logic state, with a consequent brief flash from D2.
PARTS LIST FOR CMOS LOGIC PROBE (from Maplin Project Book One, 1983)
How Pen Drive Works?
September 20, 2011 at 7:33 pm
“Pen drive” is another name used to describe a certain type of universal serial bus (USB) flash drive. Pen drives are NAND-type flash memory cards that can be plugged into a computer’s USB port. The term “Pen” refers to its size. This type of flash drive is so small that it can fit into the palm of your hand or hang on a lanyard. Also, it is often flat and rectangular, similar to the shape of a highlighter pen.
Pen drives are used to store data. These flash drives vary in storage capacity (64 MB to 32 GB) and are removable and rewritable. Techies often purchase pen drives as replacements or backups for CD-R’s or floppy disks. However, the average Joe unwittingly purchases pen drives in the form of iPods and MP3 players. Yes, iPods and MP3 players are the most popular form of pen drives these days. And, the key to their success lies within their circuit boards.
When a pen drive is connected to a USB port, it activates. Otherwise, it lies dormant. The USB port gives the pen drive access to information on a specific computer. Because most pen drives are formatted using FAT or FAT 32 File systems, they are compatible with almost any USB host/port on a computer.
Data is read, transmitted or rewritten from a pen drive to a computer (or vice versa) after it is properly connected and manipulated through a program. For example, after an iPod is connected to a computer, music can be downloaded to it or extracted from it by the owner. This is usually completed through programs like iTunes. Programs such as this are able to interface with pen drives in order to exchange information.
Internals of a typical USB flash drive
1 USB Standard-A plug
2 USB mass storage controller device
3 Test points
4 Flash memory chip
5 Crystal oscillator
7 Write-protect switch (Optional)
8 Space for second flash memory chip
Today, companies that specialize in technology are working to improve on the pen drive. A lot of it has to do with storage capacity and other issues that limit its use. Meanwhile, the pen drive is being marketed in fashionable ways in order to attract a variety of consumers. Basically, the developers of the pen drive are finding unique and innovative ways to make it accessible to everyone.
August 19, 2011 at 5:34 pm
Another name for a chip, an integrated circuit (IC) is a small electronic device made out of a semiconductor material. The first integrated circuit was developed in the 1950s by Jack Kilby of Texas Instruments and Robert Noyce of Fairchild Semiconductor.
Integrated circuits are used for a variety of devices, including microprocessors, audio and video equipment, and automobiles. Integrated circuits are often classified by the number of transistors and other electronic components they contain:
•SSI (small-scale integration): Up to 100 electronic components per chip
•MSI (medium-scale integration): From 100 to 3,000 electronic components per chip
•LSI (large-scale integration): From 3,000 to 100,000 electronic components per chip
•VLSI (very large-scale integration): From 100,000 to 1,000,000 electronic components per chip
•ULSI (ultra large-scale integration): More than 1 million electronic components per chip
PSCP module 2 qstns
August 19, 2011 at 5:32 pm
1. Write an essay on control statements in C .
2. What is the difference between ‘while’ and ‘do while’ statements.
3. Explain the ‘break’ and ‘continue’ statements.
4. Which are the different ways to make an infinite loop ?
5. Write notes on :
1 . 1-D array
2 . 1-D array declaration
3 . 1-D array initialization
4 . Reading 1-D array
5 . Displaying 1-D array
6. Explain linear searching with example .
7. Explain Binary searching with example .
8. Explain Bubble sorting with example .
9. Write notes on
1 . 2-D array declaration
2 . 2-D array initialization
3 . Reading a 2-D array
4 . Displaying 2-D array
IF ANY PADIPIST IS INTERESTED TO SHARE SOME NOTE. PLEASE DO POST HERE IN THIS PAGE SO THAT THE OTHERS MAY ALSO BECOME A PADIPIST
July 3, 2011 at 5:47 pm
Characteristics Features Of A Computer
July 3, 2011 at 3:28 pm
Characteristics Features Of A Computer
There are 8 important characteristics features of a computer. This post give you an idea of Characteristics of a computer. A computer is an electronic computing device which performs the execution according to the given set of instructions called program. It accepts the data, processes it and produces the information.
Main Characteristics of Computer
The characteristics of computer are Speed, Accuracy, Automatic, Endurance, Versatility, Storage, Reduction of cost, Intelligent quotient.
Celerity (High Speed)
It denotes the speed of a computer. The computer present in the modern world has the speed of nano and pico second. The various speed that are used by the computers from the former generations are as follows:
1 milli second=1*10^-3 second
1 micro second=1*10^-6 second
1 nano second=1*10^-9 second
1 pico second=1*10^-12 second
Thus the speeds are measured.
It denoted the accuracy of the computer. They are reliable and robust. It ever makes a mistake. Most probably the error occurs due to the user rather than the computer. There may be certain hardware mistake but with the advanced technique in hand they are overcome.
Example: Only accurate robots are used to perform the operations for the patients since human hands are not flexible for making operations.
The computers are automatic. It may execute the process without any intervention of user once they are assigned to a work. Once the data or instruction are fetched from the secondary devices such as optical disks, hard disks etc. Immediately they get stored into
RAM (primary memory) and then sequentially they get executed.
This denotes that the computers never get tried as the humans do. If there are surplus amount of executions to be made then each and every execution will be executed at the same time period. They can perform their assigned task without taking any refreshment.
Example: Computers which are used for controlling the satellites.
In our day to day life computers has been a part, with their extended flexibility they are used, all over the world. They can be used as personal computers, for home uses, for business oriented tasks, weather forecasting, space explorations, teaching, railways, banking, medicine etc. All Modern computer can perform different kind of tasks simultaneously.
Secondary storage devices are the key for the data storage. They store the data for which the user wants to retrieve these data for future use. The examples for various secondary devices are Floppy disk, Optical disks (CS and DVD), Zip drives, Thumb drives etc. The data of smaller size can be easily fetched and they can be copied to the primary memory (RAM).
Example: Data Warehousing made by IBM.
Cheaper (Reduction of cost)
Computers are short term investment in order to achieve a long term gain. Though the investment is high they reduce the cost of each and every transaction. They reduce man power and leads to an elegant and efficient way for computing various tasks.
Needs a User interface
The only draw back of computer is it cannot make the decision of its own. It needs a guidance to enhance the process. After all computers is a machine
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