About Me

Harischandra Prasad Tirumani

History

      When I was child my father used to bring lot of science books which has lot of nice experiments. I used to try my self some of them which I could do at that age. My father bought a small projector which projects pictures using film. We used to enjoy a lot with that. But slowly I was starting doing projectors myself using magnifying glass and Sun rays reflected using mirror. When ever I get holiday I used to do all these kind of stuff. I used to collect film rolls that were used to project movies in movie theater. They can be projected with our home built projector by pulling film roll fast to create animated effected(but no sound of course). My father has fitted a motor to his bicycle, which used to run on petrol. He used to do some modification to it and maintenance by him self. Also house hold electrical works also does him self. Even though by profession he is Teacher, he used to do all these stuff by him self. May be due to that I am also interested to do stuff myself like DIY and some experiments. Did some experiments with batteries, incandescent bulbs, and other stuff. I started learning electronics from my brother. When he was studying his electronics and while he was doing his projects I was fascinated with the stuff that he was doing. Even though those electronics subjects are not part of my regular education, I started learning from him as from child hood I am very much interested in doing experiments and DIY stuff. I used to do lot of experiments that was described at the end of each chapter. Will update with more details…

My memories with Electronics

  • Barking Dog
  • LED
    • Once my brother brought different colored LEDs and he showed them to me and said they will lit. I could not believe that they will produce light. He connected resistors and power supply. Wow! Its really amazing to see the light from them.
  • Giant Video screen with RGB LEDs
    • Once, I guess in 90’s, I went to a railway station in Chennai, India. There I saw a huge LED screen playing a video. I am very impressed with that screen and I thought of constructing a small screen with LEDs. Later when I was planning to do digital dash board for my bike,  I thought of doing with LEDs, but I bought LCD and later OLEDs as they will give more resolution. But still I have not done my digital dash board, its long pending project. Hmm!
  • Of course all my projects that I did while learning and while experimenting and while creating to use them.
  • Will update with more details…

Books

“Nitya Jeevitam Lo Bhouthika Sastram”(Physics for Entertainment) . I read this in my native language, Telugu.

First circuit…

Once my brother made a circuit(Barking Dog) that was published in an electronics magazine. No PCB, no general purpose board, but all of the components are hanging in air and joined by twisting the component leads within them self. Its a big success. After seeing that I got more interest into Electronics and started looking into them, of course I am still in schooling at that time.

My first circuit

Even though I have done lot of things with electrical circuits, the first electronic circuit that I made was with UM66. Will update with more details…

The circuit that inspired me to learn Digital electronics.

In fact two circuits. One of my friends was studying Mechanical Engineering(IIRC, I was studying 10+1 at that time). He has done remote controlled switch with complete digital logic circuits. Another one was a circuit that was published in EFY(Electronics For You). Will update with more details…

The circuit that inspired me to learn Microcontroller.

A circuit that was built using 8751/8951 microcontroller. The circuit consists of single IC and all pins are tied to LEDs. In that project details it was said that LEDs will light in different patterns and lot of stuff. After seeing the circuit I did not understand how it can happen as nothing is there, no flip-flops, no counters, no logic gates just one IC thats it. I was scratching my head to understand how that will work. So, my ultimate guide is my brother, went and asked him. He explained how it works. First I am surprised and then I am impressed with that microcontroller and started learning more about it. That is when I started learning MCS51 family microcontroller. Will update with more details…

Circuits that I made while learing

I made lot of circuits while learning and after that as well.

A few of them:

  • Musical sound generators using UM356x and with multiple ICs.
  • Calling bell for home with different musical sounds.
  • Metronome.
  • Clap Switch.
  • Fixed and Regulated power supplies.
  • AM and FM audio transmitters.
  • AM and FM receivers with discrete components and with ICs as well.
  • SSB decoder for my existing AM radio receiver.
  • Audio Tape Player.
  • Audio Tape Recorder.
  • Audio Tone controller(Bass, Mid-range, Treble etc).
  • 5-Band Audio Graphic Equalizer.
  • Lot of audio amplifiers – With discrete components and with ICs as well.
  • Speaker cross-over network circuits.
  • Audio level indicator with LEDs and VU meter.
  • Digital Frequency counter(With discrete logic gates, no Microcontroller).
  • Digital Frequency generator(With discrete logic gates, no Microcontroller).
  • Digital clocks with 7-Segments displays.
  • Temperature display using LM35 and microcrontrolle.
  • Electro-mechanical volume control with discrete logic gates;ex:4013, 4017, stepper motor(No Microcontroller).
  • Morse code generator.
  • Lot of stuff with LEDs.
  • AC powered Blue colored LED lamp which consumes less than a watt. It is in active and always ON state since 2002 and still running even now in 2015.
  • MCS51 development board using Static RAM as EPROM – I had also written a companion IDE in Visual Basic and Visual C++.
  • EPROM emulator using Static RAM.
  • EPROM eraser.
  • EPROM Reader and Burner.
  • … and lot more.

– Harischandra Prasad Tirumani

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