CORE_TECH

This stabalised power supply circuit may be directly connected to 230V AC mains to derive output voltages of 3V to 12V DC for connection to the prototyping board. 230V AC mains input is down-converted to 15V AC by step-down transformer X1, whose secondary winding can support a current of 2 amperes. A bridge rectifier converts the AC to pulsating DC with a peak voltage level of 21V (15x1.4142). LED1 lights up to indicate the availability of output from the rectifier. Resistor R1 (2.2-kilo-ohm) limits the current through LED1 to a safe value below 10 mA. The output from the bridge rectifier is smoothed by 470µF capacitor C1. Capacitor C2 bypasses high-frequency ripple. An adjustable, LM317T series 3-terminal, positive-voltage regulator is used at the output of the rectifier section for regulation. It is capable of supplying in excess of 1.5A over 1.2V to 37V output voltage range. However, here it has been used to supply discrete voltages in steps of 3V, 5V, 6V, 9V and

Most audio signal sources have only one stereo output, which means they can drive only a single pair of headphones with a resistance of around 32 ohms or a single line of 600 ohms. But sometimes several people are required to connect their headphones to a single audio signal source—such as for entertainment, e-learning and training, or at home. In these situations, use of powerful loudspeakers is not desirable because other people in the room will get disturbed. Also, sometimes the signal from one audio output needs to be sent to several power amplifiers located many metres away from each other. In that case, the distribution device should be able to drive long audio lines with resistance between 100 and 600 ohms. Presented here is a solution to such a requirement that adds a distribution buffer (DB) between the audio output and the headphones. Most headphones have some kind of volume control. Therefore no volume control is added to the distribution buffer to keep th

Presented here is a simple circuit that can drive two motors for a small robot, allowing the robot to negotiate an obstacle course. Two light-dependent resistors (LDRs) are used to detect the obstacle and the motors are driven correspondingly to avoid the obstacles automatically. Two H-bridge motor circuits are used that can drive each motor forward or backward, or stop it, independently. Circuit and working Fig. 1 shows the circuit of dual motor control. The circuit is built around four-channel multiplexer CD4052 (IC1), light-dependent resistors (LDR1 and LDR2), four BC547 npn transistors (T1 through T4), four BC338 transistors (T7, T8, T11 and T12), four BC327 pnp transistors (T5, T6, T9 and T10) and a few other components. Fig. 1: Circuit of the dual motor control As mentioned earlier, there are two H-bridge circuits to drive the two motors. Motor M1 drives the left side, while motor M2 drives the right side. Each H-bridge circuit is built around a pair of npn and

Keep your  Microsoft files safe and secure. Set password to Microsoft Office files (.doc ,.ppt, etc) to make  safe and secure. -First open  any Microsoft office's component such as Word, Powerpoint, Excel etc.    -Click on Office button   -Click on Prepare                                              -Then new window opens . There click  on  'Encrypt document'  -Enter the desired password in the 'Encrypt document' window. and click Ok.   -New window appears asking for confirm the password . Then click OK.     Password is set on the file. And whenever we open the file it will ask for the password first.                                                                                                        

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Get Lion Transformation pack 1.0 which transforms your Windows OS to Apple's Macintosh OS. It is a nice theme check out some of the screen shots here : - Click download button to download the theme.

Use the below Windows 7 keyboard shortcuts to make the most of your Windows 7 experience. Windows key and the arrow keys Pressing the Windows key and Left or Right arrow keys will dock the window your viewing to the left or right-hand side of the screen. Pressing the Windows key and the Up arrow will maximize a window and pressing the Windows key and the Down arrow will resize and then minimize the window. Use Shift: To stretch a window vertically, press the Windows key + Shift + the Up arrow. If you have multiple monitors use the Windows key + Shift + the Left or Right arrow keys to move the window to another monitor. Windows key and plus and minus keys If you ever need to zoom in or out of what is being displayed on your screen press the Windows key and the + ( plus ) or - ( minus ) keys. Pressing the plus zooms in and once zoomed in

Most computer users don't take full advantage of the computer Mouse. Below are computer mouse tips and secrets that help you get the full potential of your computer mouse and increase your overall productivity while on the computer. Shift key and mouse click Many text editors and programs allow you to highlight all or portions of text using the Shift key and the mouse. For example, place the cursor at the beginning of a paragraph in a text editor, hold down the Shift key and click at the end of the paragraph to highlight the full paragraph. Bonus tip: Holding down the Alt key while dragging and highlighting text in a text editor will allow you to selectively highlight text. This can be useful if your paragraph or other text is in a column. Take full advantage of the scroll wheel Today, everyone is familiar with a mouse wheels ability to scroll up and down on a page. However, this wheel can also do so much more, below ar

With the return of the fine weather, you’ll doubtless be enjoying lazing around of an evening on your patio or in your garden, but even if you’re not surrounded by marshes or other shallow water it’s very likely some intruding mosquitoes will come along to spoil this idyllic scene. Although indoors it’s easy to get rid of them these days, indeed even to prevent them coming into the house, the same can’t be said for the great outdoors. We might mention the well-known Chinese coils – the only thing Chinese about them is undoubtedly their name – which very often drive people away as much as mosquitoes, if not more! Moreover they are nasty things to handle. There are also UV (ultra-violet) ‘electrocutors’ consisting of a blue lamp surrounded by two closely-spaced grilles between which a high voltage is applied. The mosquitoes (and fies and other flying insects) are supposedly attracted by the color of the lamp and as they approach, get electrocuted in contact with the t