Building a DIY 5.1 Audio Video Receiver – Part 7

Now that I have the front speakers, rear speakers and sub-woofer working, the next thing I wanted to do in my DIY AVR project was to bring up the center speaker. I ordered a TPA3118 amplifier board for Rs. 379 towards it. The only problem with the board (which I did not realize when I ordered it) was that it does not have a volume control. The repercussions of this mistake will soon become clear. Anyway, I connected the board to a 12V power supply. The same one that was powering the crossover board from my previous post. Output from … Continue reading “Building a DIY 5.1 Audio Video Receiver – Part 7”

Building a DIY 5.1 Audio Video Receiver – Part 6

In the last post I mentioned that I was looking for a crossover board. The one that I purchased is putting out a huge DC bias and I was not comfortable using it on my sub woofer. Wondering if it is a problem with the particular unit that I got, I ordered a replacement. Unfortunately, even the replacement has the same signature output. So I decided to do something about it myself. AC coupling capacitor For those of you who have done electrical engineering might recognize that adding a capacitor in series with the load will block DC offset. This … Continue reading “Building a DIY 5.1 Audio Video Receiver – Part 6”

Building a DIY 5.1 Audio Video Receiver – Part 5

So far I have finished bringing up 4 of my 5.1 speakers in my DIY 5.1 AVR project. If you missed, check out part 1, part 2, part 3 and part 4 of the series. Next I wanted to bring up my sub-woofer. Since I have an active sub-woofer, I did not need any amplifiers to drive it. I just need to connect the output signal from my audio source directly to the sub-woofer input. But there is a catch. If you connect the audio source directly to the sub-woofer, the sub would be wasting a lot of energy which … Continue reading “Building a DIY 5.1 Audio Video Receiver – Part 5”

Building a DIY 5.1 Audio Video Receiver – Part 4

As I mentioned in my last post, after measuring the frequency response and testing the TDA 7498, I decided to buy one more. The board I bought earlier did not have the right LC filter for a 6 ohms speaker. It was designed for 8 ohms speaker. So I decided to use that board for my rear surround speakers which were also 6 ohms. However, it is fine to have a slightly poor quality amp for the rarely used rear speakers. Then I set out searching for another TDA 7498 speaker amplifier board with a 680 nF capacitor RC filter. … Continue reading “Building a DIY 5.1 Audio Video Receiver – Part 4”

Building a DIY 5.1 Audio Video Receiver – Part 3

The TDA7498 class D amplifier board that I purchased to power my front speakers was working great. The audio quality is at par with what my Pioneer 5.1 AVR delivered using class AB amplifier. I could not tell the difference in audio quality. None the less, I wanted to make sure the quality is really as good as my ears led me to believe. Enter a function generator and oscilloscope to make sure the frequency response is satisfactory over the range of audible frequencies (20 Hz to 20 kHz). If you don’t happen to know, a class D amplifier uses … Continue reading “Building a DIY 5.1 Audio Video Receiver – Part 3”

Building a DIY 5.1 Audio Video Receiver – Part 2

If you did not read part 1 of building a DIY 5.1 AVR, I suggest you start from there. Here is some important points from my previous post — decided to go with a class D amplifier start with a 2-channel amplifier for front speakers the front speakers are rated at 130W and 6 ohms After searching through a lot of class D amplifier chips, I finally decided to go with TDA7498. They are rated for 100W at 6 ohms and that should be sufficient. Although I have the 130W speakers, I never really ran them at full power, so … Continue reading “Building a DIY 5.1 Audio Video Receiver – Part 2”

Building a DIY 5.1 Audio Video Receiver – Part 1

Alright, you already know the story of my electronics going puff during a power surge. One of the electronics that got burnt was my unnecessarily expensive Pioneer 5.1.2 AVR. The reason I put emphasis on unnecessary is because I rarely used all the features of the device. Don’t even know why I spent all the money :). After it stopped working, I opened and checked everything that I could figure out. But I didn’t notice any obvious problems. The AVR just boots up, turns on the amplifier relay and turns off. Since it failed during COVID lock down, I couldn’t … Continue reading “Building a DIY 5.1 Audio Video Receiver – Part 1”

Tax Filler Script

The Indian tax filing has become even more tedious now. Going forward, starting from assessment year 2020-21 (financial year 2019-2020) one needs to report each and every equity redemption that results in long term capital gain in Schedule 112A. It used to be optional last year. Instead of reporting every transaction you could just report the aggregate value. But it is not optional anymore. This increases the burden on the tax payer especially if you have made a lot of small transactions. This change applies only to equity transactions that have incurred long term capital gains. So the debt transactions … Continue reading “Tax Filler Script”

Building A Periscope With Cardboard

I think I can build a career making cardboard toys. Every time my daughter has an “idea” for a toy, I have get ready to build something out of cardboard. After the doll house, disk drop game and rolling ball machine, the latest idea from my daughter was to build a periscope. She probably saw some youtube video of some one building it. The idea was to make a hollow rectangular cylinder and attach two small mirrors on the ends at 45 degrees. We bought some mirror toys from the local stores for this purpose. Then removed two mirrors out … Continue reading “Building A Periscope With Cardboard”

Rolling Ball Machine Construction

After building a doll house and disk drop board, my daughter had another idea for a cardboard project. This time she wanted to build a rolling ball machine. Again, as usual, I comply. I had no idea of what she had in mind. So I asked her to do a drawing and explain how the machine is supposed to work. She drew a spiral on paper, cut it out along the pencil drawing. Then, pointing at the dangling spiral, she said “that is what I want”. She explained to me that the balls will roll from the top and spiral … Continue reading “Rolling Ball Machine Construction”