Back in 1998, I was in high school and I'd caught the HiFi bug from my dad and a few of his friends, so I started getting into speakers and amplifiers and 5.1 sound and even laserdiscs. (remember those?) I decided to build my own 5.1 amplifier. Unfortunately I knew practically nothing about real circuit design, so I used amplifier cards put out by Marchand. I designed the enclosure and power supply though, and had the monstrous (1.2kW@80% duty) power transformer custom built for me by Tortran. The father of a friend of mine ran a machine shop, so they both helped me build the case out of scrap aluminum. Here it is looking at it from the outside:
And the back:
And inside:
You'll notice there's room for one more amp, this is because when I was designing this the Dolby EX standard was just coming out (I remember Gladiator being one of the first DVDs to have this) that called for a middle-rear sixth channel. There's substantial physical contact with case plates and the heatsink, so the whole case is one huge heatsink and barely gets warm. Here are the supply filters, on the PC boards I etched in my backyard, then reinforced the copper plating with strips of copper sheet soldered on for more current handling. Yes, that would be 225,000uF per rail, quite the overkill but it didn't stop me. At least I'm not going to go Gaincard and say that LESS filtering produces better sound. (idiots)
It works subjectively great, since back then I didn't have any fancy measurement equipment it couldn't analyze it objectively. It puts out 5x100W continuously without breaking a sweat, and weighs about 50 pounds. It has since been retired because my parents have been using my room to watch movies and the complication of a separate preamp, amp, surround decoder, DVD player is just too much. Now I have a DVD player and an integrated surround amp. Fewer cables is nice, must say.
Toward the end of my time in high school I got into old-school video games, namely the Neo-Geo. When I was little I wasn't allowed any game machines, but I remembered there was one machine, the Neo-Geo that was way cooler than all the rest. Of course this coolness fetched a price premium, and still did when my interest surfaced. Therefore I went about "consolizing" a game board built for the arcades. There are whole legions of people out there who do this so it wasn't anything remarkable, although I do feel my version is particularly easy on the eyes.
I finished this project about two weeks before leaving for college, and as a result never got to fully enjoy playing until I already outgrew my appreciation for it. I still keep it around as I now have a more general appreciation for what I consider to be "aesthetically pleasing electronic design," a quality which I feel is fully embodied by the Neo-Geo hardware, designed in the early 80's.
My first year at the university I started to build a good collection of electronic tools, and I needed a bench supply. A quick look at prices compelled me to build my own, resulting in this cute box:
Actually, the background is more telling than the subject itself: we've got Windows Media player playing some probably downloaded music (I forget the dominant file sharing program of the time, I think it was still Napster), we've got the obligatory crappy blue plastic cup, some variant of which is purchased by all freshman students their first week of school, we've got the Palm V which sadly didn't get any use until it was painfully outdated, there's a corner of an Nsync poster (no excuse there), and coolest of all we've got a Sun mouse, since my secondary computer was an Ultra 5.
A quick peek inside shows the somewhat poorly laid out interior, including the circuitry to drive the variable supply and the current meter with output select.
My second year in school I was convinced I should be a digital designer, so I took the eponymous class. In the end I made a "digital turntable" by which you could control the playback pitch, forward/reverse of a CD as if it were a record, meaning scratching effects were possible. This was modeled after a product by American DJ which had just come out that year, following my vague interest in such endeavors. I think the coolest part of the whole thing is how the record speed is tracked, with a stripped optical mouse. Other than that, it was just a bunch of PALs and CPLDs. It should be noted that the whole thing could fit on one 10K gate FPGA, which we had available, but I declined to use as I enjoy routing pretty bus lines.
A year later I'd taken an E&M theory class, which effectively shattered my understanding of "current needs to circulate in a loop" as I understood it, since I never previously considered "thin air" as part of any closed loop. It should be noted that three RF chips later, it still blows my mind. Anyway, I took it upon myself to design a Tesla coil that would be: small, cheap, and pretty. These parameters satisfy my engineering frugality without conceding any aesthetic standards.
In the end I paid about $40 for the whole thing, the majority of the cost absorbed by the capacitor bank because I didn't find any good surplus caps at the moment. A pity that right after I found a few pounds of even better capacitors for a handful of singles, but that's life. The primary transformer came from surplus, the spark gap I fashioned out of two dorsoventrally drilled bolts and two pieces of tungsten welding electrode.
The capacitor bank is one of those series parallel things, the input filter I made from parts salvaged from speaker crossovers, and the secondary transformer is made from copper drain pipe, a pill bottle wound with #30 wire and a doorknob. It's a pity that I'll never see full performance out of this Tesla coil because of secondary to primary leakage, which I unsuccessfully attempted to mitigate with the plexiglass shield. Fortunately the secondary is being rewound, the story of which you already have half seen with the coil winder project... I'm also planning on using an Alpha CNC lathe to turn a toroid topload. In due time, in due time. All the same, it makes some nice sparks.
The next summer I took a short break from electronic things, and did some machining. Well, it's not completely free of electricity but the majority of the hurdles in this project involved a big lathe from pre-World War II and a milling machine. Here's the rotor of a 10KW generator:
and what it looks like as it's being assembled:
At this time I was living with people who loved to camp and do outdoorsy type things, and one of the toys they had around the house was a tin can stove made from internet instructions. I looked it over, and decided it would be fun to try my hand at it. I took advantage of unlimited machine shop access, and produced this:
It's turned out of a solid 3" bar of aluminum, and so while it's slower to start than the real tin can stove owing to its higher thermal mass, it can really get going:
I dub this an official failure, because compared with the real tin can stove which costs nothing if you lose it and weighs 10 grams, this would make me cry if I lost it and weighs 80 grams. That weight differential is like asking an ultralight camper to pack a sledgehammer, apparently.
Once the semester started (we're in the fall of 2004 right now) I had a brief rekindling of my interest in old-school video game hardware, thanks to a freelance job I got which required me to design a video decoder circuit. Once the job was done, I took one of my prototype video decoder boards and stuck it in a box along with a reconfigurable PIC-based controller decoder, and got a mini-JAMMA interface.
You can see the breakout cable for Capcom 6 button fighting games, mostly the only arcade games I played. It's got component video outputs, which as far as I know is the first true component decoding board that existed for this purpose (the Jrok board soon followed though). The top will accept neo-geo style 4 button controllers or the Sega Genesis 6 button controller, whose buttom remapping can be changed by pressing the "mode" button. Inside you see the two boards:
And once again disgusting wire layout. You can see the audio is unconnected on the right, because I built it primarily for CPS2/3 boards (which, by the way, were JUST cracked!) that all have the on-board Q-Sound RCA outputs. I have today it's fun to see the "Credits 0/0" on your screen, then press a switch a few times and see the number go up like a slot machine. Like free money, except it's free money so you can spend more time rotting your brain playing video games.Right about then I discovered the MIT hobby shop, and a world of speaker building possibilities opened up. My HiFi tendencies had up to this point laid dormant, since living in cramped spaces with other people who many not share your taste in music tends to stifle sonic expression. Still, nothing could stop me from building speakers!
These are the satellites I made for one of my cousins' subwoofer/satellite systems. This cousin likes mostly eclectic jazz (I have no idea the formal genre name) and lots of vocals, not necessarily much at high volumes. So his speakers have very good midrange in exchange for bass clarity and output level. You can tell this is my first attempt at a gloss spray painted finish: although this picture is particularly unforgiving it's nothing special at any angle.
I'm a big fan of sub/sat systems. When done right, they give the sound of larger speakers, but with much greater placement flexibility and a much less intrusive visual presence. Better yet, it takes some more good engineering to get them right, which makes them a challenge. Finally, small satellite speakers are just darn cute.
Here are the satellite speakers for my other cousin; this one likes more traditional jazz and the occasional loud martial arts action movie, so it has better lower bass (for reproducing the low bass strings) and greater output level. You can tell I gave up on the spray finish, mostly because my makeshift spraybooth had to be taken down.
They get the same subs, though: 8" ported woofers. These drivers are monstrous yet still sound tight, due to a correspondingly stiff suspension to go with that giant magnet. They were a surplus win from Apex Jr.
Finally, I made myself a triplet. I wanted to go slightly nuts, so I got a Hi-Vi SP10 woofer, which was actually so heavy (30 lbs) it was shipped in its own wooden enclosure! To go with this monster I needed efficient speakers, so I chose MTM satellites. Here are the satellites before painting. What makes me sad is in the background you can see my custom shelf system I constructed for my desk. It had cubbies for my oscope, two different soldering irons, part trays, signal generator and my monitor. I had to leave it in MA when I left because it was too heavy. :(
Here is a speaker after painting, in its natural environment of my old apartment. You can tell I got a bit better at the spray painting.
Here's the sub on the floor, an 11" sealed cube. I'd be lying if I said I wasn't going for the Sunfire look, but honestly I doubt this sub performs a tenth as well. Bob Carver's Sunfire sub is engineering genius.
Now that I don't live in MA anymore, here are my speakers sitting on the floor in my dad's HiFi room. No use for them in Italy! We're having some work done on the house so the HiFi room is in a bit of disarray at the moment.
Here are my dad's reference speakers, the incredible Bella Voce Signatures, a really kind gift from the designer himself. Behind you see the old reference speaker, a Vandersteen Mk II. You also see the drop cloth everywhere.
I had a bunch of other projects, but they were all lost when my hard drive gave up the ghost. Thankfully I learned my lesson, and I'm doing daily incremental backups!
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