Monday, May 11, 2009

Still Miss my Camera

This is the Konica Minolta DiMAGE X50, which was a steal for an ultracompact at the time, and was very fast to boot. In insufficient light, the picture quality was pretty bad, with a lot of noise, but this was typical of ultracompacts at the time. It did take some pretty good shots when the conditions were right though. I really miss it. Okay, it's sitting right in front of me, but I think I left the charger at home my mother's house.

Looking back at previous posts, the picture quality was something I took for granted. Of course, many shots could have been better with maybe a little more sunlight and a tripod, but I was lazy.

Anyway, I noticed there was a jack on it, labeled 4.7V DC.

It's pretty hard to see it in this photo, but even if it were working I wouldn't be able to take this shot with the X50 anyway.

So I thought, hmmm 4.7 volts, that's pretty close to 5 volts, which is the USB standard. "Maybe I could charge this thing from a USB port!" I thought.

So I went down to the dollar store and then Radioshack and made this:

Well, it didn't charge anything. While hooked up, the camera tried to start, but couldn't. After being connected a while, and then disconnecting, it wouldn't even try to power up. After some googling, it turns out that jack was for an AC adaptor to use the camera off of instead of batteries. It didn't charge the battery. And apparently the USB standard of 100 mA wasn't enough for the camera to run off of (the USB standard allows up to 500 mA, but it must request it from the computer, which may or may not grant the device such current, depending upon the power settings).

I really should have done a little more research before hurrying out the door to Radioshack again. At least this time I saw someone I don't normally see working, all the other times I felt like such a regular.

Saturday, May 9, 2009

Power Supply (for phono stage)

I finally built my electrical engineering course project, it's horrible, I'm not even going to post a decent pic of it. However, it has inspired me to hopefully pursue robotics (BEAM in particular) this summer.

It left my new-old-foundatafreesigninfrontofabankruptbusiness'soldlocation folding table setup a mess (this was an early picture, it got much worse than this).

I should take a full proper picture of it folded up, it's so cool. I wouldn't have finished my project without it, my desk is way too cramped. Here it is, equally flooded with parts and tools and such.

Also, much of the work was done at night, so I would have bothered my roommate much (either with solder fumes, or the cold of having the windows open).

What to do with all my parts and tools out? A power supply for my Very Simple Phono Stage of course! The basis of which is a completely blank 24 V DC power supply from my local electronics store, along with an adjustable regulator, a pot, some caps, etc etc.

It took much longer than I thought. Instead of boring you with circuit details and how I asked the good people of Head-Fi for help, here are the pics.

PSU on the left during testing. The heatsink was remarkably cold during a few hours of operation, which was a relief. It's so small! That huge capacitor is a 1mF.

The blank wall wart. It does its job and gets a little warm. There is a 24v dc regulated Elpacs wall wart on the right, but that is for my PPA :D

And the psu, with the preamp in the background. Notice how I partially wrapped it in aluminum foil for shielding (only the bottom of these enclosures are metal). I swear it sounded better after I did it (okay, I guess I can't really tell since it could be placebo all the same). Linda Ronstadt's voice in particular sounded exceptionally better, as well as Jenny Lewis's. My speaker's strong point is mids anyway.

I love that little fuse holder, and the heatsink, and the toggle switch, everything. It's so cute.

Also, I saw this little gem at Rasputin's the other day. If it weren't for that price tag (it's used), I would have bought it.
Pretty hilarious if you ask me.

I feel so bad with these terrible pictures. I hope my camera charger turns up soon, or else the li ion inside will permanently die D:

Friday, May 1, 2009

Crappy Pictures

I've been meaning to post for some time now, but my camera battery died and I can't, for the LIFE of me, find the charger.

So this update will be mostly full of pictures taken by my phone.


I've only been able to listen to my new (old) turntable using my old receiver. I wanted to see if it was holding it back.

So I looked around for phono preamps, so I could maybe plug that into another speaker amp or one of my headphone amps. If I wanted to spend less than $100 I was pretty much limited to DJ models (probably fine, just something in the back of my mind steering me away from anything with the word DJ on it) and cheapos. So, naturally, I searched for DIY solutions. One of the first (edit: the first) results was a thread over at diyaudio about the Very Simple Phono Stage.

It was essentially an opamp, power supply, and a bunch of resistors and caps! The comments in the thread said it sounded pretty good, and the justification included some kind of keeping-it-simple argument, which made sense to me.

I had an extra OPA2132 opamp from my cmoy (since in my cmoy there is now an OPA2107, which sounds much better in that application), and I figured I could just make it battery-powered (using a psu for the cmoy, since I had yet another opamp available) for the time being, since I didn't want to make something that I had to plug directly into the wall. I don't think I'm ready for that kind of thing yet. Also, the toroidal transformer recommended by the author was like $35.

The parts total was around $20, not including the opamps of course, but the resistors, caps, enclosure, sockets, a switch, and some RCA plugs.

I made a test version on breadboard (for my project, which I have yet to complete lolololololololol)

At first it sounded like crap, then I realized the output caps were too small by a factor of a thousand lol. Then I bought nonpolar 4.7uF electrolytics, slapped 'em in, dropped some Empire Strikes Back soundtrack in the Kenwood, and I was blown away.

Nothing I have ever owned has ever sounded that good.

And this was the breadboard version, with all the extra resistance from the mechanical connections, all the extra parasitic capacitance from the untrimmed resistor and capacitor leads, etc etc.

I cased it up yesterday afternoon, and I seriously think I got high off of the solder fumes. Not a good thing. Anyway, here's what it looked like halfway done:

And all cased up:

Instead of making a screw terminal for the grounding wire that all turntables (should) have, I soldered a wire (not seen) from ground and had it press against the metal base. That way, I could just attach the groundwire as shown:

I'm listening to it right now. I've been listening to it for hours. It sounds so good.

Also, I moved my speakers and receiver, they sound much better now! My bookshelf speakers are on a bookshelf lol. And I'm less worried about the music coming from the speakers resonating with the tonearm and creating an ugly feedback sound since they're relatively far away now.

This is my third Spring at college, and every Spring, around the same time (before finals) I've undertaken and finished a project. I guess it's the aggressive procrastination at work :DDDD
From top to bottom, and in chronological order, the cmoy headphone amp, the alien dac, and the very simple phono stage.