softwareng

Author: misamaliraza94

  • Comparator Based Crystal Oscillator

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    misamaliraza94
    in

    Although a simple crystal oscillator may be built from one comparator of an LT1720/LT1721, this will suffer from a number of inherent shortcomings and design problems. Although the LT1720/LT1721 will give the correct logic output when one input is outside the common mode range, additional delays may occur when it is so operated, opening the…

  • Baud Rate Generator

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    misamaliraza94
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    In this article, an RC oscillator is used as a baud rate generator. If you can calibrate the frequency of such a circuit sufficiently accurately (within a few percent) using a frequency meter, it will work very well. However, it may well drift a bit after some time, and then…. Consequently, here we present a…

  • Processor Fan Control

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    misamaliraza94
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    Fans in PCs can be objectionably loud. In many cases, the amount of noise produced by the fan can be considerably reduced by lowering its speed. Although this will decrease the amount of cooling, this need not be a problem as long as you don’t go overboard with slowing down the fan. Particularly with older-model…

  • Case Modding

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    misamaliraza94
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    The aesthetics of ‘case modding’ (modifying a PC’s enclosure) offer plenty of scope for debate and plenty of scope for original circuits. Low current LED indicators are usually fitted in PC enclosures. Although this certainly saves energy, the LEDs do not light particularly brightly. It is not completely straightforward to replace the low-current types with…

  • Automatic Mains Disconnect

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    misamaliraza94
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    Downloading and CD-burning programs usually provide the option of automatically shutting down the PC on completion of their tasks. However, this energy-saving feature is of little benefit if even after the PC has been switched off, all of the peripheral equipment remains connected to the mains and happily consumes watt-hours. The circuit shown here provides…

  • Serial To Parallel Converter

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    misamaliraza94
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    This converter may help if just the serial port on a personal computer is free, whereas the printer needs a parallel (Centronics) port. It converts a serial 2400 baud signal into a parallel signal. The TxD line, pin 3, CTS line, pin 8 and the DSR line, pin 6, of the serial port are used…

  • CD-Rom Drive as Digital-Audio CD Player

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    misamaliraza94
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    A CD-ROM drive can be used as a stand-alone unit for playing digital audio CDs without interfacing with a computer. The stereo output of CD player available at the audio jack can be amplified using audio input facility which is normally available on a tape-deck/tape-recorder or a stereo amplifier. Audio socket on front/rear of the…

  • Alarm Clock With Day Selector

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    misamaliraza94
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    This circuit disables an alarm clock on Saturdays and Sundays when people like to sleep in but enables normal operation on Mondays to Fridays so that people rise in time for work or school. The core of the circuit is a 4017 decade counter which acts as the day counter and it is used in…

  • Egg Timer

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    misamaliraza94
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    This egg timer, which is both simple and functional, shows once again that it is not essential to use a microcontroller for everything these days. The circuit consists of only two ICs from the standard 4000 logic family, a multi-position rotary switch and a few individual components. The combination of a 4040 oscillator/counter and a…

  • Isolated 1-Hz Clock

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    misamaliraza94
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    One of the author’s physics projects required an accurate 1-Hz (seconds) clock signal. Unfortunately, precision 10-MHz quartz crystals are expensive, while another problem was found in the inability of most common or garden 40xx CMOS logic chips to work at such a high frequency. However, a typical CMOS counter like the 4017 has such a…