Junaid's Blog

Author: Junaid

  • 3.7 to 1.5 V Buck Converter with MC34063AP

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    Junaid
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    My daughter got a toy train which uses AA sized battery cells to operate. It has space to put two AA cells in parallel, so it requires just 1.5 V to work. To avoid buying AA cells, I tried to make it rechargeable with a 18650 lithium-ion cell with protection board having USB port. But…

  • Edit PDF Metadata in Ubuntu 18.04

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    Junaid
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    I see pdftk get first in list as most recommended way when searching for editing PDF metadata in Ubuntu. But pdftk is no longer present in Ubuntu 18.04 repositories. Found a different tool named PDFMtEd, which is actually a GUI front-end for ExifTool.

  • Create PDF from Image Files and Resize PDF to Standard Page Size

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    Junaid
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    First convert image files to PDF with command: Then resize PDF to standard size with command: Read more about pdfjam at here.

  • SEPIC Converter Calculations For Fixed Output Voltage

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    Junaid
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    Attached document demonstrates calculations involved for a SEPIC converter. Calculations are based on “AN-1484 Designing A SEPIC Converter” by Dongbing Zhang from Texas Instruments.

  • Electret Mic Stereo Preamplifier

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    Junaid
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    I was looking for a simple per-amplifier circuit. Found one at http://www.minidisc.org/mic_preamp/Simple%20Stereo%20Electret%20Mic%20Preamp.htm. I made minor modifications and here is my version.

  • LED Light with CYT1000B

    LED Light with CYT1000B

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    Junaid
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    Lighting LED with AC main supply were not that easy. Mainly it required some sort of SMPS with current controlling circuitry. But it is changing. Now there are integrated circuits available specially designed to help to light LEDs with few extra components. One of such IC is CYT1000B. I like CYT1000B more compared similar ICs…

  • തെർമോക്കപ്പ്ൾ

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    Junaid
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    ചൂട് അളക്കാനായി ഉപയോഗിക്കുന്ന ഒരു വഴിയാണ് തെർമോക്കപ്പ്ൾ. രണ്ട് വ്യത്യസ്ത ലോഹസങ്കരങ്ങൾ ചേർത്തുണ്ടാക്കുന്ന ലളിതമായ ഒരു ലോഹക്കഷ്ണമോ ദണ്ഡോ ആണിത്. ചൂടിന്റെ അളവനുസരിച്ച് ഇത് വളരെ ചെറിയ അളവിൽ വൈദ്യുതിയുണ്ടാക്കും. അതിന്റെ വോൾട്ടേജ് നില ചൂടിന്‌ ആനുപാതികമായിരിക്കും. ഇങ്ങനെയുണ്ടാകുന്ന വോൾട്ടേജ് നില അളന്ന് അതിൽ നിന്നും ചൂട് എത്രയാണ് എന്ന് കണക്കുകൂട്ടി കണ്ടെത്താൻ കഴിയും.പക്ഷെ തെർമോക്കപ്പ്ലിന്റെ വോട്ടേജ് നില നേരിട്ട് അളക്കുന്നത് ശരിയായ രീതിയല്ല. കാരണം വളരെ ചെറിയ വോൾട്ടേജായിരിക്കും അത്. ഉദാഹരണം ഒരു K ടൈപ്പ്…

  • Nginx Configuration for WordPress with HTTPS Enabled

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    Junaid
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    Few days back I switched back to WordPress from static site generator Hugo. On my server I am using Nginx as web-server though I am more familiar with Apache Web Server (Now I can’t remember exactly why I switched to Nginx?!). I am using LetsEncrypt SSL certificates and always redirect regular HTTP traffic to HTTPS.

  • Thermocouple Amplifier with OP07C Op-Amp

    Thermocouple Amplifier with OP07C Op-Amp

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    Junaid
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    Recently I created a soldering station based on Arduino Pro mini. It has to read temperature data from a thermocouple within the soldering iron. Thermocouple produces a very little voltage, around up to 30 Milli volts for soldering irons. So, the soldering station uses an op-amp based circuit to amplify those small signals from the…

  • Switched to Hugo

    Switched to Hugo

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    Junaid
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    I switched to Hugo as static site generator for my blog on last Sunday. I was using Stagen, a static site generator wrote myself in Node.js, from March of 2016.