Skip to main content

Posts

Showing posts from November, 2012

Some Definitions of Electronics

AC Alternating current. Consists of a periodic oscillation between two different voltages. Usually said to look like a sine wave, but is not always.AM Amplitude modulation. In radio communications, a signal controls the amplitude of a carrier wave that is at a much higher, constant frequency. The carrier wave is filtered out and a loudspeaker plays based on the amplitude of the signal.Ampere (A) The SI unit for current I. (Commonly spoken as "amps", "milliamps", etc.) The ampere is officially defined as that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one meter apart in vacuum, would produce between these conductors a force equal to 2×10-7 newton per meter of length. There is another definition which is based on the deposition rate of silver (in electrolysis?), which is much easier to measure. The other electronics units are derived units based on the ampere…

Next-Generation Space Ambitions Keep Rolling

As space shuttle Atlantis rolled to its new home at the Kennedy Space Center Visitor Complex earlier this month, NASA and its commercial crew partners reflected on the Space Shuttle Program's tremendous accomplishments and vowed to continue America's leadership in space.

Mercury's Water Ice Bodes Well for Alien Life Search

The radar image of Mercury’s north polar region from Image 2.1 is shown superposed on a mosaic of MESSENGER images of the same area. All of the larger polar deposits are located on the floors or walls of impact craters. Deposits farther from the pole are seen to be concentrated on the north-facing sides of craters. Image released Nov. 28, 2012.
CREDIT: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/National Astronomy and Ionosphere Center, Arecibo Observatory
The discovery of huge amounts of water ice and possible organic compounds on the heat-blasted planet Mercury suggests that the raw materials necessary for life as we know it may be common throughout the solar system, researchers say.
Mercury likely harbors between 100 billion and 1 trillion metric tons of water ice in permanently shadowed areas near its poles, scientists analyzing data from NASA's Messenger spacecraft announced Thursday (Nov. 29).
Life on s…

NASA | Tour of the Moon

Although the moon has remained largely unchanged during human history, our understanding of it and how it has evolved over time has evolved dramatically. Thanks to new measurements, we have new and unprecedented views of its surface, along with new insight into how it and other rocky planets in our solar system came to look the way they do. See some of the sights and learn more about the moon here!

What is a Higgs Boson (Quick overview in plain english)

A quick description of what a Higgs Boson is and why it's important.
Want a more in depth look into CERN and the research? check out my 1hr BBC documentary http://youtu.be/HVHxSOm1oEo

Contactless Mains Voltage Indicator

This is a CMOS IC (CD4033) based circuit which can be used to detect presence of mains AC voltage without any electrical contact with the conductor carrying AC current/voltage. Thus it can be used to detect mains AC voltage without removing the insulation from the conductor. Just take it in the vicinity of the conductor and it would detect presence of AC voltage. If AC voltage is not present, the display would randomly show any digit (0 through 9) permanently. If mains supply is available in
the conductor, the electric field would be induced into the sensing probe. Since IC used is CMOS type, its input impedance is extremely high and thus the induced voltage is sufficient to clock the counter IC. Thus display count advances rapidly from 0 to 9 and then repeats itself. This is the indication for presence of mains supply. Display stops advancing when the unit is taken away from the mains carrying conductor. For compactness, a 9-volt PP3 battery may be used for supply to the gadget

A simple Remote control Tester

Here is a handy gadget for test- ing of infrared (IR) based re- mote control transmitters used for TVs and VCRs etc. The IR signals from a remote control transmitter are sensed by the IR sensor module in the tester and its output at pin 2 goes low. This in turn switches on transistor T1 and causes LED1 to blink. At the same time, the buzzer beeps at the same rate as the incoming signals from the remote control transmitter. The pressing of different buttons on the remote control will result in different pulse rates which would change the rate at which the LED blinks or the buzzer beeps. When no signal is sensed by the sensor module, output pin 2 of the sensor goes high and, as a result, transistor T1
switches off and hence LED1 and buzzer BZ1 go off. This circuit requires 5V regulated power supply which can be obtained from 9V eliminator and connected to the circuit through a jack. Capacitor C1 smoothes DC input while capacitor C2 suppresses any sudden spikes appearing in the input sup…

Light Barrier Detector

This simple circuit using a single transistor turns ON the relay when light falls on the LDR.
The potentiometer is adjusted for the required sensitivity.
The power supply is 6V.
Be careful about the impedance of the relay. Its impedance should not be less that 60ohm.
Its working can be explained as follows:
With the light falling on the LDR,its resistance is low and the transistor is saturated and turns the relay ON.
When light is obstructed, the LDRs resistance becomes very high. The potentiometer shorts the transistors

base to ground and it is cut off. Hence the relay is OFF.

Telephone operated remote control using PIC16F84A microcontroller

This design controls up to 8 devices using a PIC microcontroller (PIC16F84A) connected to the phone line. The unique feature here is that unlike other telephone line based remote control, this device does not need the call to be answered at the remote end so the call will not be charged. This device depends on number of rings given on the telephone line to activate/deactivate device
C source code complied using HT-Soft PIC C compilerCompiler Hex code file to be directly programmed into the PIC  Instructions for the telephone operated …

PC based Frequency Meter

Here is a simple technique for measuring frequencies over quite a wide frequency range and with acceptable accuracy limits using a PC. It follows the basic technique of measuring low frequencies, i.e. at low frequency, period is measured for a complete wave and frequency is calculated from the measured time-period. Cascaded binary counters are used for converting the high-frequency signals into low-frequency signals. The parallel port of a computer is used for data input from binary counters. This data is used for measuring time and calculating the frequency of the signal. The block diagram shows the basic connections of the counters and parallel port pin numbers on 25-pin ‘D’ connector of a PC (control register 379 Hex is used for input). External hardware is used only for converting the higher frequency signals into low frequency signals. Thus, the major role in frequency-measurement is played by the software. The PC generates a time-interrupt at a frequency of 18.21 Hz, i.e. after …