away?

You may be wondering where have i been after that random post? Well im just here and there and everywhere? haha. Nah, i have been bust with my amp and im so excited cause i can predict that if nothing goes wrong, it will be ready by tonight! I have loads of pictures which i would really wish to show, but due to time constraint, its hard. So look out for the space above this post to see my new amp :P

random

This shall be a rather random post. Here goes.

I am pretty sure that many of us have heard before of the story about a 1/4 filled water bottle and the many different ways in which a person can look at it. One such way is that you can think of the bottle as " Hey there is 1/4 of water in the bootle! Thats great!" and alternatively you can think of it as "Oh dear, something is not right cause 3/4 of the bottle is not filled!". It really depends on how you want to think of it and how you want to accept it.

Well, many a times this story is used to encourage people to look on the bright side of things and its not really the end but ever thought of "you" being the one trying to tell the story, know of this story and truly follow it yourself? We keep telling such stories to friends and such, but when it comes down to performance indicators, do we ever see that the 1/4 of the bottle is filled? I am rather sure that most of the time, most, but not all, of us only can see that the 3/4 of the bottle is empty , little will we realise that there is actually this 1/4 of the bottle being filled. In fact, I feel that demands and expectation actually minimises the 1/4 such that it almost appear negligible to oneself. Isn't it such an irony for such a story which is suppose to be encouraging to not be accpeted in the eye of the performance analyser?

Amp Update

Today i went to my father's office to build the chasis for my amp. Since a picture speaks a thousand words, i shall just use pictures (:
My present, wraped in newspaper. Hmm, whats inside the wrapping paper. Aluminium sheets! Precut somemore... (okay that sounds lame)

Mock up of the whole thing. Shall eventually spray it black.

Then we began drilling 15mm deep holes using the bench press.Look at that! So long!

For the tapping part, we used a portable drill, set it to low speed and tap.

Thats about all for today. Only managed to do the tapping for the top and bottom of the heatsinks, the front and back have to wait till later. It sure is hell lot of work!

MRC handover day

Today was MRC handover day. The new comittee members are as follow:

President: Kang De
Vice President: Zhen Ning (yar thats me)
Secretary: Zhong Xian
Treasurer: Shermaine
Quarter Comittee: Colin, Xiang Jun, Joe, Kee Ann

So there it is. I felt rather sad that the seniors are leaving us. All seems just so fast. Well, have to accept it ba.

Together, this new comm shall lead MRC to great success!

Council Investiture 2007

Great work they got there. Very very grand in my honest opinion. I was up there in the cage on the mixer. Stress level not as high as before, like chinese new year which i totally screwed up. But anyway, the whole investiture was quite well done except for the start where the cue was given to play the music and i played but then the council people didn't walk out. A few seconds later, we had a council rush into the cage telling us the people haven even reach the door!! Okay okay, i faded out the music and then Miss Annie came out and repeated "I present to you, the student councillors. Again." It was really quite funny but then all went on quite smooth after that.

I was rather touched by maggie's speach. Not just because of she thanking us MRC but it was an overall thing. The way she phrased everything and stuff, was just meant to touch peeple. The first CCA she thanked was MRC, and indeed it touched me to know that someone out there actually still knows that we are always around, suporting various events "secretly".

Through this investiture, i learned that council is quite a fun thing. I stayed on for their recession and really saw the other side of council. They were actually giving out presents to teachers and councils. The councils first gave the 5 teacher in charge presents and they were very very creative presents in my opinion. There was one for this teacher called: eeker tanial?! Don't really know how to spell it but its pronounced it this way. So the first present was this card showing a new kind of evolution from ET to 一个大牛 to Tuna. I couldn't really get the tuna part but it was just funny la. So after that card, the council people gave him a back massager with a cow head soft toy on its tip. Then came the fun part. He was given 2 custom shirt. The first one was a white shirt with the words, 一个大(a cow head). The next T-shirt was one with the words tuna. But it was designed to look like the Puma style. So instead of the words Puma, it was replaced with the words TUNA and instead of a leopard, it was replaced with a flying tuna -_-. Quite lame but it was hilarious!

Ahh its just so sad that half a year has gone and various CCA leaders are stepping down already. What have i done this half year? I don't really know. Its like i just closed my eyes and half a year is gone.

Oh ya. From council investiture, i learned one thing too! Old teacher does not necessarily mean naggy. Trust me on that. I learned that FIRST HAND. Haha!

Amp Update

Righto. Reached home at like 8+, then took a shower and started working on my amp before dinner came. What i had to do was to remove the parallel resistor so that i would have a effective resistance of 1.2Ohms along the output stage in order to decrease my bias current
Instead of 2 resistors, now there is only one. so its 1.2ohms

Each channel has its own heatsink.

Everything needed to run the whole thing.

Now some maths. With voltage of 0.739V and a resistor of 1.2Ohm, we have:

0.739=(I)(1.2)
I=0.616A
Power that is continuously dissipated.
P=VI
P=(32)(0.616)
P=~20watts

Thats alot of heat considering im not using it to cook anything. It works already and there is sound. I would really wish to borrow my father's office oscilloscope and check for oscillations here and there. But anw, theres sound already. I have yet to do a proper listening test so cant really comment on the sound. Must wait till it gets fitted into a box, which will be my aluminium casing (:

Jia Qian's Mum

She passed away, while giving birth to twins. Its really a sad case. Her mother went under the operating knife to deliver the twins but after the operation, she could not stop bleeding. Her wound was oozing with blood that could not clot. The hospital, R*ff*e* hospital, told them that they could not give her anymore blood because they have already hit the quota and their blood supply is running low. Indeed she was given 20packets of blood which is 10 litres of blood. Thats alot. The family made a agreement with the doctors there that if they found people to donate blood, the hospital would release more blood. So the next day many of us received smses asking us for help. Most of us went to help, i wanted to but i could not because i just donated my blood not long ago. The blood bank had more blood but after that, im unsure of what happened. I suppose she got more blood. I heard that her mum was in stable condition soon after but the next day, she passed away.

The newspapers reported on this and its a very hot news now. Sadly and annoyingly, the hospital is actually claiming that they were willing to provide as much blood as they could to her mother. It is just super annoying. Shying away from responsibility? It has not been the first time i seen such cases already. Last year, my grandma passed away also under the surgeons knife. She was admitted to the hospital just to undergo a simple surgery to change her broken bone to an artificial one. The chance of survival as claimed by the doctor was 90%. 90% mind you. My cousin, who was a doctor too, encouraged my grandma to undergo this operation. Who knew what happened? The incision was made, and immediately, my grandma went into cardiac arrest. She had a heart attack in the middle of the operation? I don't know. But what i knew was that when my uncles and parents probed the hospital for the reason behind my grandma's death, they were wishy washy and very very inefficient. Excuses were that the doctors was on leave. Very "efficient" i must say.

I feel very sorry for Jia Qian and her family. Just hope that her father will stay strong. Not easy to bring up 4 children now. Pray that they would not meet with any big problems. To end it off, i will quote what her father said

"Does Saving A Life Require Approval?"

Chinese Orals

Gone. Screwed. Quite badly done im my opinion. I had difficulty reading the passage and smoked through 4-5 words. Confirm the examiners would have picked it out. Then came conversation. The question was something like: Nowadays there are alot of people posting their photos online to share, do you think this hould be encouraged? And i went: yes it should be encouraged but there are the negative sides of it too. Did i answer the question?!?! hmm. Then i only said like a few points and started err err erring until the examiner could not take my errs anymore and said: you have said quite alot already so let me ask you another question. Dead. Towards the end, i was very nervous already and it was pretty obvious that the examiner wanted me to be gone. Okay dead.

0_0?!

Wat the! Another cap went kaput again! But then this time i was pretty darn sure i did not wire it wrongly! I guessed that it was a surge problem cause my cap bank is like 30000uF which draws a very very high current momentarily when just turned on. I suspect it could be due to that problem and then somewhat confirmed it after hearing from my dad that Tantalum caps cant really withstand surges in power.

This time the blowing up was even more POWERFUL! I was wiring everything up on my second channel and decided to turn it up after checking the wiring. So i turned the power on and POP! Saw a damn big spark and then saw the cap actually shoot out of the circuit board?! So scary la! Very lucky again cause i wasn't sitting in the "firing range". I think im going to change all the tantalum caps on my circuit to either ceramic caps or just use the electrolytic cap la.

A trip to my father's office

After countless tries of drilling with a simple hand drill, i decided that the quality sucks big time and decided to ask for my father's help. He was really open about me building another amp this time round:)

I was super excited cause i got to use this machine:
Its a heck of a drilling machine and the good thing is, its precise. I was rather surprised when i got to know of the price tag of this machine, around 100+. Wah such a precise machine and it costs less than a Black and Decker hand drill?! WOOTS!

Pop goes the capacitor!

Yikes! So scary! I hooked everything up to a speaker and turned it on. It seemed normal but then there was no sound although there was an incoming source. So i thought that it was just a matter of loose connection but upon checking it wasn't. The thing was powered down and i checked for problems. Then i realised something. Something very very very strange that i could not explain initially but after consulting the simulator i managed to figure it out. I actually soldered the +ve supply for the opamp to ground. So it effectively was a short circuit. That explains why there was this pop sound when i first powered up the whole circuit. What puzzles me is that how come even with the +ve side missing, due to the short, why can it still bias itself right? Quite strange

But anyway, the scary thing was this. I happily resoldered back the +ve supply to the opamp's +ve input and turned that thing on again. "PIACK" and black smoke arose. WTF HAPPENED?!?!?!

I was stunned to see that but quickly switched off the whole thing and waited for the large caps to discharge. Honestly speaking, i was pretty lucky cause i took safety precaution before turning it on if not that cap would have exploded in front of me! I went to the look at the circuit board and guess what i saw? This ---->

Looks allright right?

Hmm whats that line along the side of this cap?WTF!The black marks are the results of the cap blowing with great velocity.

Im seriously not sure what happened. Its a tantalum cap and it is a polar cap. Im pretty sure that i did not connect it wrongly. So what happened?

Its Alive!

Yes my amp is alive! This morning i worked on the power supply and after lunch, i decided to connect it all up! Yay it works! Haha but at the start i connected one wire wrongly. Its the Base and Emitter of the transistor that i connected wrongly and i just swapped them around and there was magic! Here are some pictures:

Power supply in the making. Cap bank of 30000uF per rail. +/-16V, full wave DC rectification.Mounted the amp onto the heatsink

Connected everything up togetherTurned it on and it works after repairing one fault.

Now time for some maths. As you can see, the multimeter is reading 734mV. So in other words its 0.734V. The yellow and green crocodile clips are measuring the potential difference between this 0.6Ohm resistor.

V=IR

0.734V = (I)(0.6Ohm)

I = 1.22A

Thats a reasonable quiescent current. But after letting it idle for awhile, its current quiescent current is around 1.21A which is still a reasonable value. Most probably i would bias it even higher to around 1.5A cause my heatsink is like damn big and now the heat emiting from it is quite low.

Now gonna hook a speaker to it and have a listen. See ya!

messed up

Things haven't been going the right way for me. My results are really a mess. I have like great scores and sucky scores. What a spread in the spectrum-.- I got 44.5/60 for chemistry and i topped the class with that, 54.5/100 for chinese and i failed physics, terribly. Im happy for my chemistry and glad i passed chinese but physics? How could i have failed that? I used to be so good at it in secondary school and now im like a total noob at it. This feeling just sucks. Im so going to mug physics.

I miss talking to you. We used to chatter alot and it really was on any random subject, but now? We don't even say hi to each other anymore. What happened? How in the world could such a friendship just die in such a short time and just like that? We worked so hard together to try to achieve what i thought was our common target. I thought we had that common target, that same mentality, the same thoughts but maybe i was wrong. I don't know.

Just like that and it all ends? Was our friendship really worth nothing to start with that it can be ended just so easily? I don't think so but do you?

chinese

I so hate chinese now. Yes my chinese is very very bad. Lao Shi told me today that she is quite disappointed with me because my results dropped alot from the start of the year. I felt very disappointed cause i really did study for chinese and all she could say is she is disappointed. Now who would be disappointed then? Im so not going to waste so much time on chinese anymore.

Mum's Sick

Mum is really sick. She hasn't been well for the last 3 weeks. Seeing her condition get worse day by day just makes me feel very upset. I can really feel the agony in which i can only see her feeling very sick and yet not being able to offer help. Her illness is quite strange. She complains that she has breathing difficulties and feel very weak. At times i would just check on her while she sleeps, carefully observing to see if is she still breathing. Yes i know it sounds very wrong but the fact is that i cant bear to let her go.

She cooks for our whole family almost everyday. Relentlessly doing the housework with no strings attached. Unconditional love. She came home today with a very pale face and dashed straight to the toilet once she reached home. She was feeling very uncomfortable.

I can only hope that she would get well soon.

Amp Update

Recently i posted the circuit i drawn on diyaudio. The people there are very friendly and they helped me out and pointed out to me that the way i implement my CCS would result in me having a very unstable bias. So they recommended me to change it with a better one that was not so temperature dependant. Here is the new schematic: http://img.photobucket.com/albums/v384/zning/NewSchematic.jpg

Went down to Sim Lim Tower(SLT) today after Physics SPA which i screwed it quite a bit because i forgot to change the units. Got some new components and went home to start soldering. Jin Zhe tagged along too. During the buying process, i was trying to find this opamp, OPA2134. Because it was not a general purpose opamp, it would be very difficult to be found in SLT. So i gave up on it and thought that i should just order it online through RS Comp or Farnell. But then, before i made my way home, i decided to go get some blackgates from Well Audio Labs at Burlington Square. Over there, Frankie, the owner of the shop if im not wrong, was very very friendly. Bought the blackgates from him and then i asked if did he sell opamps. He kindly replied no but then referred me to farnell and rscomp. Then i told him that i could not buy cause i did not have credit card but then he said is can one. Then he referred me to a company called Federal in SLT and said that they could bring them in for you. I was super happy and glad that i actually made my way down to Well Audio Lab to buy blackgates cause i not just got my blackgates but also got valueable information. Thanks Frankie! Went back all the way to SLT and went to federal. The people there were generall friendly but then i had not a very good experience cause this guy cut the queue and went first before me. Can't really blame him too cause i was like flipping through Farnell's and RS Comps catalogs so most likely the sales person was like "are u going to order something?" But anw, ordered the OPS2134 and it will take one day for it to arrive but i can only collect it on thursday. So here's some pictures!

started off with components, breadboard, schematic and fulscap paper for planning.Transferred the plan from fulscap paper to the breadboard. The lines are actually the busses that can be found behind the breadboard.Don't you think it looks like some weird art piece?Started soldering and in the end had this big forest of pins at the back.This is my "custom made" resistor. Its rated 6W and its 0.6Ohms. Its actually just 2 X 1.2Ohm 3W resistor soldered together in parallel.
So this is the final piece.
And i broke them into 2 (:

Now is to wait to get my hands on a drill and then drill my aluminium bracket so that i can mount the power devices and test it.

Oh! I got my aluminium plates cut to size already. Total there are 4 pieces, 2 big 2 small, with one of the 2 smaller pieces having a rectangle and 6 holes being cut. I think the rectangular hole was cut using a plasma cutter. Thats according to the lady i spoke to who helped me out.

Cant wait for it to be fully assembled!

Flight Of The Bumble Bee

Here is a little something that i recorded a few weeks ago. Feel free to give comments (: