Returning from the Hog Feast to realize that my amplifier is working again!
To quote Stimpy: "Joooyyyy." :-) I definitely had a funny hunch about
the chip, especially because after the glitch it was totally cool
— whereas fried chips usually heat up more than healthy ones.
Probably the protection circuits were at work after all, and they took
some time to recover.
You might wanna check the link again as there's a new picture, in case there are the electronics. It does look like it could be quite cool, or what? At least that's the logical conclusion because it's certainly not hot. The most heat seems to be generated by the transformer, and even that isn't too much. Of course the trafo is also in contact with the heatsink, now painstakingly isolated from the chips.
Hog Feast was, once again, proof that Christmas does come more than once a year. This time everything was smoother and better than ever, thanks to new logistical decisions. That meant some woodwork on Friday afternoon, for instance Opo and I built a dining table for outdoors. It was a genuine hack with a chainsaw and a hammer.
Besides the usual meaty stuff, I had the chance to taste two new species: bear and king crab. The latter deserves special attention as the beast is huge, and even a section of one leg has plenty to chew on. I've put some pictures into my photo gallery and there's one that shows the enormous claw. There's little point in explaining more about the party for other people, but perhaps the photos can give some idea.
I should add one bit about the conversations that take place at the
Hog Feast. These are not usually very intelligent or profound, and
particularly at this time I appreciate emptying my mind slightly,
enjoying the moment, and not pondering anything too personal there.
However, this time I got into quite deep, meaningful and informative
chats on topics like quantum information and operational amplifiers.
How cool is it that, just when I'm in the middle of building a chip
amp, I get to talk with somebody who designs opamps?
The amplifier project went through some interesting ups and downs
today. I'm getting nearly finished with the case, but it's not quite
there yet so I won't give out any pics. Mounting the amplifier blocks
to the heatsink which is the top of the case, I noticed I'd missed a
couple of screws from my shopping list. I went to the basement looking
for something I could use to attach the PCB, even some soft steel wire
would do as it didn't need to be tight, just keeping it in place.
Quite by accident I found a small plastic bag with exactly
what the doctor ordered; these were just like the other screws in the
amplifier, except for the length that was just right for that place.
Now that was cool but my luck didn't last too long. The ICs had the quirk that the heatsink tab is at the negative supply voltage, -36 V in my case (pun intended). I had thought of isolating the case from the ICs, but it didn't seem essential so I left it connected for now.
There was a little 50-Hz hum on the speakers, nothing major but still suboptimal. I verified that it was due to the proximity of the transformer, as lifting the amps further away made it silent. I also realized there were loops in the ground and the negative voltage: the signal grounds were connected at the sound source (the 3.5 mm plug has common ground), and the V- was looped via the heatsink. Well, at least one good reason to isolate the ICs.
So, I was lifting the plate to get it farther from the trafo, and suddenly it hit the left-channel input ground. *spark*. I didn't think it could do anything worse than blow the fuse (of course the system has its own fuse). But I smelled something funny. The scent of freshly baked electronics. The left channel didn't work again.
After some debugging it looks like I fried the chip. The short-circuit current had in fact gone through the IC, using the route from the V- pin to the heatsink tab. I'm still not sure how that could do the damage, considering the chip has some clever protection against heating and overcurrent, but apparently the engineers hadn't planned for this!
Now, of course I'm pretty pissed off, where 'pretty' is the description of the amplifier case ;-). I've been going through hardware hacker vocabulary, including the name of my desktop machine, mostly because my digital multimeter refuses to work, which greatly impairs the debugging. It's a cheapo meter which has already been replaced once by warranty. At some points I resorted to using a DC motor to test for current :-).
What makes this situation inconvenient is the difficult availability of those chips. Of course I should have ordered an extra or two as I went through the trouble of ordering them. This episode also makes me want those LM3875TF versions which are insulated already, but they're even harder to find. Damn and blast!
Yesterday I was looking into another possible audio hack. On the GainHog pages I mention
that my portable CD player's headphone output was screwed and
something had to be done. The player does have a lineout as well, but
with the power amp I need some volume adjustment.
After tracing the PCB for a while, with the occasional multimeter aid, I found that the chip near the jack was doing the amplification for the headphone part. It said BA3575FS so after some googling I had a complete diagram of the chip available. As one interesting bit I found that the Auto Volume Limiting System (thankfully optional in the player, and only affects the headphones) was provided by this chip where it's called Auto Volume Control. Of course it's not a Sony chip so their marketing just had to rename the feature.
Because the left-channel output was at -1 VDC I considered the possibility of a short circuit. The chip was heating up a lot, and a short would create such enormous currents. However, the AVC/AVLS is a current limiter, so I could check it by turning the feature on; the chip ought to cool down. This did not happen so I conclude the chip itself is b0rkken.
Even if it's a SMD chip and hard to solder, it might be a nice challenge to change it. I would need to find a replacement first. Even Farnell doesn't have it and it looks like this chip only goes to businesses who make such players, as it's quite useless for anything else.
Of course, I'm now using one of my computers to play CDs. In fact my long-term goal is to have a single silent machine for playing all media, so I won't need a switching/attenuating box between the sources and the power amp. But I think a standalone CD player would be better, at least compared to Willow which I'm using now — Prkl is too noisy for proper listening, albeit it's my only source for movie playback. I do have a desktop CD player with headphone output as well, it's currently in my parents' system but of course I can take it back any day.
So, with all these possibilities for media playback you may understand why I want a single system that does all :-). It will need to have massive passive cooling, perhaps with one of the VIA CPUs. Though I don't like their current Mini-ITX motherboards. I'd rather take something more expandable, after all the passive cooling takes up space and I could use some PCI and AGP slots.
Tuesday has been a very nice experience overall, something I haven't had
in ages. A sense of accomplishment in the best possible sense: firstly
because I finished the amplifier electronics so quickly, and secondly
because the result turned out so damn good. There was definitely a
sense of flow in it; even though I had planned the project little by
little over previous months, there were some nice improvisations made
I have gotten partially used to the new sound which is more neutral and frank than before, but I still find surprises in music I've listened over and over, little details. From a Fourier point of view it is clear: if the frequency response is not flat, there is blurring in the time domain. Of course the present system is not perfect, but I believe its impulse response is closer to the optimal delta function than my previous systems.
Solved a number of interesting problems today. Compiled 2.4.21 with
the CK patch for Willow as well, as I had some ALSA problems and I
wanted a fresh install. During the reboots I solved a riddle I'd had
for a long time concerning Ethernet: it did not start properly at
boot, I had to do it manually.
Well, the only times I'd booted Willow were due to hardware-induced crashes. Now that I did a clean boot, the network started properly as it should. It was a simple lock file issue (of dhcp client) that, of course, didn't clean up if there was a crash. I've identified some obvious crash-inducing scenarios the sound card when trying to do full duplex, perhaps it isn't made for it.
But for the real news: my component order arrived today, including power opamp chips, millifarad elcas, metal film resistors, some microphone cable and gold-plated connectors. I'm talking some serious audio stuff. I've already finished with the electronics, and I can say the amplifier sounds very enjoyable!-) There's more work left with the enclosure but I won't rush it as I can already enjoy the sound. For more info see the GainHog page, it'll probably be updated frequently these days/weeks.
Compiling 2.4.21-ck1. That
looks like a nice patch with low latency and related goodies, as the
official lowlat patch isn't available yet. Looking forward to boot it
with a little more bleeding edge.
The day hasn't been particularly fascinating to me personally, but the political atmosphere is interesting as our Prime Minister Anneli Jäätteenmäki resigned after only 63 days in office. Great to have something to talk about with relatives and others besides the weather ;-).
Which brings to mind the rain and kewlitude forecast for midsummer this weekend. I don't actually mind, I'm just looking forward for next weekend when it is time to hog the pig.
I had a problem with the ck1 patch, it hung the system at startup; the kernel booted fine, but the
init script for loading the UK keytable got stuck. My first attempt
was to try the 'core' ck1 patch instead, as it contains the low
latency and batch scheduling that I needed (explanations below).
It didn't help, so I just disabled the keytable script and booted again: it works fine. The interesting bit is that I do have the UK keytable assigned nevertheless. It seems that the keytable is also loaded by /etc/rc.d/rc.sysinit. So the /etc/init.d/keytable is redundant and I'll leave it disabled.
Now for the reasons I wanted the patch:
I have just watched an utterly beautiful movie, The Legend of 1900. In the
great What's Up tradition I will now analyze it to death ;-).
There were several scenes where I was simply frozen with awe, absorbed into the flow of the movie. All of these were performances of 1920s/1930s piano rags or related kinds of jazz. That was a key foundation of the movie, and probably the most important factor for me, as I happen to love that kind of music. I will need to get the soundtrack some day, even if it loses much of its impact without the story.
According to some reviews, seafaring was another foundation for the story, but in my opinion it was not, not even intended. The steam ship did provide a convenient, isolated setting for the main character — awesomely played by Tim Roth — to develop his symbiosis with the art.
The cinematography was a worthy complement to the story, with hints of fantasy in both. In fact one of the most inspiring scenes works so well because it is a delicate combination of music, narrative atmosphere, and visual effect, while neither of the individual elements would haved been particularly interesting in isolation.
As to the story itself, I won't spoil it much, but it walks the fine line between the profoundly thought provoking and the naïve. At least when considered as a whole afterwards, as it is hard to think objectively while enjoying the ride. This masterpiece will definitely go to my list of those that need to be watched again in a proper theater.
My precious Latvian amplifier died (again) on Tuesday night. After some
tactile glitches where I cycled it on-off-on a little too quickly
(which normally isn't bad, just a pop from the speakers), the
left channel crashed. It doesn't respond to the inputs or controls, instead
just roars along at some multiple of 50Hz.
I've decided that's enough with the amplifier. It was such an ugly kluge to begin with, and I've repaired and modified it too much already. Fortunately I have some plans as for its successor. I'll keep everyone updated when things go forward. As a matter of fact, it's interesting to have my room so quiet. Since I don't have much use for Prkl as a media station without sound, I don't even keep that machine running, which means some extra quiet.
Last night I saw a Finnish underground film called Ripa ruostuu. The name itself is quite neat, because Ripa, in addition to being a generic and old-fashioned nickname for Risto (not for me!) means 'handle', so the verb for rusting makes a nice wordplay. And as we know in the geek circles, a nickname is basically a handle.
Overall the film wasn't exceptionally original as I'd already seen the leading actor Sam Huber play a similar character in another underground film, Hysteria. It was the supporting characters that made it more interesting, seeing distinguished actors like Jussi Lampi and Vesa-Matti Loiri in such obscure roles in such an obscure production.
It's now official: I've reached level 2 in the great text-adventure
game called Everything2. Another
text adventure I've been playing recently is glHack, a slightly more graphical
version of the good old NetHack. Of course, both of these operate within
the realm of yet another text-adventure game. It is called Linux. :-)
Today was also a day for some synchronicity, but I want to shut up with the details as they're related to my quest for employment. A nice complement for those events is the date of June 9, which is when my military service came to a screeching halt back in 1998. That was a Tuesday, but we liked to spell it as TJuesday. *flap flap flap*
Do you hear that, Mr. Anderson? That is the sound of synchronicity...
the sound of PLUR.
Do you hear that, Mr. Anderson? That is the sound of synchronicity... the sound of PLUR.
Time to write up the long weekend that ended as I returned from Tampere on Tuesday. The following might seem a little dry at some points, as I'm trying to be quite objective. Often I've looked for hidden meanings and messages in things, which completely contradicts with some of my basic ideals: Never ask why -- that will lead to an endless stream of questions, which always ends up with fundamental problems like 'why does the Universe exist'. Accept the fact that Things Happen. By no means this is meant to contradict with my other cliche grande, The World Is A Beautiful Place. As Roger Carpenter, a scientist who believes there is no free will, puts it: Enjoy the ride!
The way I woke up into Friday was not particularly pleasant, I'd only had a couple of hours of sleep. The premise for this trip was Hansu's matriculation party on Saturday afternoon in Valkeakoski. Hansu is a second cousin of my mother, by the way. I was going to stay the night at Milja and Jussi's place in Tampere, along with my parents. (For the newcomers here, M and J are my sister and her man.)
During the drive there, I had sslliigghhtt hesitations on meeting with Hanna. I barely knew her, having only met briefly in Jyväskylä the previous weekend. It was so random and spontaneous it was quite cool.
After a light dinner at M&J's place I called Hanna. She asked me to join a party in one of her friends' place in the city center, namely the H&M building. It felt nice to see her again, and I was glad I didn't have a clue of what was going to happen. It was a feeling of freedom, not as much in the free will sense, more like enjoying the ride.
One main point I should note on the party is that Hanna had plenty of kilju for us to drink. I hadn't enjoyed any of that stuff in years. It was great partly because it's so horrible, but also because it embodies the poor student lifestyle. Which, of course, is not much unlike the hacker's way; never pay for a service or item when you can enjoy learning, doing and making it yourself.
After getting the initial hits of ethanol, we headed for the nightclub called Doris. It had a strange retro feeling, and reminded me of the Q club in Cambridge. The music was similarly varied, ranging from stuff like Dingo's Hämähäkkimies to more danceable beats. I still had this wonderful feeling of partying with people completely new to me.. new friends, I should say. When 'Insane in the Brain' was playing, I went completely over the cuckoo's nest on the high 'stage', raving like I'd just left my brain in a jar. Hanna and others thanked me for the show. I had a great time with her, and wished the night would never end.
But of course the bar closed at 3:30, and nobody seemed to be ready to have a party. Fortunately Hanna said I could join her as she still had some kilju at her place. That was in the 7th floor (or 8th, as we say in Finland), nicely in sync with M&J's apartment. I felt immediately at home with the general mess that included a C=64 and an acoustic guitar.
Our conversation got more interesting as we shared our tripping experiences. In fact Hanna chose some appropriate music for our background, but I've forgotten about the name completely. At some point I recalled that there was going to be a partial solar eclipse in the morning around 6:30. We spent the time fairly quietly until then, mostly just trying to stay awake.
The eclipse was supposed to begin around 5:30. The sky was clear, contrary to weather forecasts of rain and cloudiness. It was no coincidence but providence, as Morpheus would have put it ;-). After all, the day was that of matriculation and end of school for many keen young minds. It could not go wrong.
Looking through the curtained window, we saw a bright thing and a less
bright thing next to it. The sun and the moon, I thought. I must have
been very tired, but so was Hanna... she didn't question the
physicist's opinion. As time went on we wondered why the two didn't
get much closer. It was almost 6:30 and I noticed that the 'moon' had
become a crescent. That couldn't be right.
An inspection through an open window revealed a real eclipse. The illusion of two distinct points had probably something to do with the windows (please, no Micro$oft jokes here). We couldn't look at it directly, of course. I quickly recalled that a floppy disk would do fine, with the cover held open, as I saw a couple of them on the desk. I knew it wasn't going to be a full eclipse, but the U-shaped glow that was left as the moon covered about 90% of the sun was a nice thing to watch at that point of the night, with the good company of Hanna and her feline companion Milla.
This is where my memory is a bit hazy. Hanna and I ended up entangled into each other on the bed. As far as we could get with our clothes on. We talked about rather personal issues that I won't reproduce here. Those were delicate moments. Around 8:30 I decided it was time to go, hopefully to get some sleep before the semi-formal party afternoon. With a goodbye kiss I walked out, and down the seven levels of stairs. It was two kilometers to my base camp, it was bright, and I was not wearing sunglasses.
Even if I have some ideas of deeper meanings, I won't put them here now. I enjoyed the time with Hanna very much and there was probably some mutuality to it. We seem to share a quirky sense of humour to some extent. The unconscious hunch that got us to meet in the first place in Jyväskylä, and assured me to join the party as I got into Tampere, definitely had something to it. When I think about the time I saw her in JKL, I recall the Matrix scene where Neo (who can see the deeper 'code' in things) meets the guy in deep meditation, and his code stands out glowing bright. But I digress. If nothing else, I'm sure we've both made good friends of each other.
I had planned some shopping for the morning, and I needed my regular
fix of electronic components. After barely managing to explain my
needs to the salesman at Bebek, I realized I wasn't fit for anything
that requires being awake, so I got back to Milja and Jussi's
apartment to get some sleep. It was bright daylight of course, but
Milja had cunningly arranged me to sleep partly under a table, and the
tablecloth formed a camera obscura where I quickly switched to
another reality level. The setup also brought to mind Plato's cave
metaphor in these times of the second coming of Matrix.
I got about two hours of nice, dreamless sleep before having to prepare for the party. It went all right, and there was a bit of adventure trying to navigate to Valkeakoski; the roadmap we used was badly outdated. My mother had asked me to bring my camera, which I hadn't planned to do myself, and we both took a few photos, but it probably tells something about my state of consciousness that we didn't take one single frame of Hansu herself. Even if she wasn't available for a shoot very much, and she's probably had professional portraits taken already, it feels a little stupid now.
Leaving the party was another milestone on the weekend, as my parents took off for Varkaus and I was going to spend a few days with M&J. That night the three of us got Reloaded, in fact it was re-reloading for me. The film worked so much better in my second viewing. I didn't get much new information though, but it was much easier to follow and look at the bigger picture. I also noted that the screen and sounds (SDDS) were much better than in the Jyväskylä theater. After all, this was Plevna 2. There seemed to be much less Matrix hype in the air, as my usual costume didn't arouse half as much commenting as it had done in JKL.
Sunday was the chill-out day when we first went to see a photo exhibition with images of Ethipia and Sudan. It wasn't particularly fun or inspiring, as the main themes were war and slavery. But the brochure had been made with LaTeX :-). After that we took a boat trip to a nearby island in Pyhäjärvi, spent an hour or so in the nature there. Got a little tan and fresh air. Returned with some Chinese take-away and prepared for a match of petanque. Milja won, of course, as she's the one who's spent the most time in France :-).
On Monday I resumed my shopping and found a nice pair of high shoes. Light and thin compared to any boots, yet high enough to work with skirts and kilts. I'd been looking for such shoes for a long time, and there was only one pair at Sokos -- after going through all the cool little stores. In the afternoon I found an open job position almost by accident, and arranged an interview for Tuesday. It's a rather conventional programming position, but it would be better than nothing. I'm waiting for the results which might lead to a second round of interviews :-/. Later on Tuesday I managed to meet Hanna again, as she'd been away seeing relatives. She was rather busy with her studies, so we didn't get into any deeper conversations, but it was nice to see her once more, before leaving the city.
Returning to Varkaus I'm struck by the simple beauty of nature. I'd only spent a few days in the big city center, so it's quite surprising. During a walk through a forest I've experienced moments similar to the afterglow of a trip. Which is in fact quite logical. A trip is a trip is a trip.
I'd bought components for mainly two circuits: air ionizer and an optical theremin. Both are now ready in very basic forms and seem to work, but will require further hacking and testing. At least the ionizer needs some casing; it produces a few kV of static electricity, and I already got a nasty hit. I don't think it's lethal though, because there's so little current -- considering the circuit draws about 50mA at 12V.
Just a quick note, I'm still at Tampere. I won't write anything proper
yet, it's a bit too unclear for me as well. I was coming here for one
night only, and the next will be my fourth. Also I can't focus on the
writing for some reason. I'm too used to my home
environment. The main point is that things are out of the ordinary
and, not surprisingly, I like them that way. Even if it's only an
illusion of free will and spontaneity.