Tag: Hardware

The First Pad

November 9, 2006 » Geek

Looks like the first pad is going to be the kick drum because I’ve misjudged the whole deal. I went to Ace Hardware today and picked up the stuff. I pretty much just guessed on everything. I bought:

  • Five 5/16″ Bolts, Approx 3″ long @ 0.19 ea
  • Seven 5/16″ Nuts @ 0.07 ea
  • Four Springs @ 0.79 ea
  • Seven 5/16″ Terminal Rings @ 2.49 total

I guessed well on the length of the bolts, the nuts obviously aren’t a guess, neither are the terminal rings. The springs, however, were not a good guess. It’s surprising how much different a spring feels in your hande versus mounted. The ones I picked are way to stiff, but I think they’ll be okay on the kick, because the beater hits a lot harder. Plus I won’t need to put padding on it to dampen the sound since the beater is some soft material anyways.

The other change in the design I’m making is to get some bolts with flat, threadless areas up at the top of them, about an inch worth. When the top board is pushed down it can catch the threads on it’s return, so that’s kinda iffy.

I also did some browsing today. See, I never actually did any poking around on the net before starting, I just got the idea and started building. It seems that DIY triggers aren’t that hard to find. Most are made of a piezo tansducers and practice pads. Example. I haven’t the slightest if that would work here. I think those are more of a range of current, as opposed to a strict on/off like a keyboard. I fully intend to go buy one after work tommorow and meter it to see if it can handle the job. That would make life much simpler. If not I can just make it into an acoustic guitar pickup.

Here are the required photo’s. The little white box is the home from the keyboard circuit board plus my little “breakout” board. I made that because I couldn’t solder directly onto the contacts, so all the connections are hot-glued and the breakout board is to reduce the amount of wiggling and tugging I do on the board to finish it up.

DK421 Hardware

November 5, 2006 » Geek

This afternoon I was without anything to do when I remembered my DK421 project, which had been shoved off into a dusty corner of my hard drive. I didn’t feel like programming any, and wouldn’t know what to do or add anyway, so I got into the hardware side of it.

The Sheets

I dug into Stephanies old room and found the keyboard from the green dinosaur, an Acer computer from the early-90’s. Anyway, I found it, took it to my room and cracked it open. Very simple device really. The keypresses are captured by switches composed of two sheets of plastic, very similar to slide-projector transparency sheets, with tracing on them. When you press the key it compresses a rubber bubble in a sheet and smashes the air, and thus the switch, down and completes the circuit. These connections go to a board with some leds and a chip for translating them into whatever goes down that PS2 cable.

I imagine that a newer keyboard might be more complicated, at least if it’s usb. Maybe not though. I only have so many keyboards to rip open.

Following the tearing apart of the keyboard I hooked it up to my old gateway laptop (it’s the computer I care the least about) and fired it up. No lights, no response. I shut it back down and figured out that I hadn’t reconnected a little black ground that had been hooked onto the metal mounting board as well as one of the pins. If you look at the picture of the transparency-stuff circuit you can see that one pin is connected only to a big spot for the ground.

The Pins

I taped it up and got it working right off the bat. Shiny. I then taped it onto the laptop in the lovely testing position illustrated here. I got a piece of thick copper wire, off of an old power supply, and generously stripped the ends (okay, my father did for me), 1.5″ at least, then coiled each end around a long finishing nail (that’s what it said on the box) and taped it up. This made for a nice, easy to control point-to-point connector for me.

With my newly created tool I fired up VIM and started shorting the pins together to see what they wrote. Okay, thats not true. First I tried tracing individual keys on the transparent stuff, but that got old real fast. It is, however, necessary for finding keys like shift. Regardless, I tried out the good old hunt and peck method, and soon had a list with more than enough keys for the drum triggers. I then tried out the shift key with a piece of spare wire, it works great. Thats an important one, because it is needed for the high-hat pedal.

The Shift Key

Well, thats enough for now. Hopefully the pictures shed some light on the matter if it’s still fuzzy. I haven’t made up my mind on what to build the triggers out of. I almost want to go the air pressure route so the switches won’t wear out to fast. I’ll also have to consider how to build and mount all this, I’m thinking PVC at this point. Off to a good start though :)

Additional Photos

More Nokia Goodness

November 3, 2006 » Geek

I’ve been messing with my 770 some more. Such a sweet device. Here’s a quick rundown of what I’ve loaded up so far:

»Maemodrac (Solitaire)
»LXDoom (And Doom wad)
»FBReader (E-Books)
»Puchi (Themer)
»Maemo Mapper (Map Reader)
»osso X-term (Terminal Emu)
»Tuner (Musical)
»GPE Calendar
»GPE Contacts
»GPE Todo
»Media Streamer

I’ve also got the stuff to mount SMB/CIFS shares and wrote two small mount/unmount scripts for my home network. It all worked nicely until I tried playing a few MP3’s over the CIFS mount. It didn’t buffer very intelligently, I watched my network monitor on the serving machine and it would spike every time the song “skipped” on the Nokia.

Looking for an answer I hopped onto Synaptic and found a UPnP server, GMediaServer since I knew there was a nice UPnP audio player for the Nokia, from the company itself actually. Hooked that up and it’s behaved so far. Don’t know what I’m going to do about streaming out video to it though. Oh well, I was going to buy a bigger rs-mmc card anyway, I can just dump videos onto that if I need to.

Here’s some screens of the UPnP media player and an XTerm. I greened up the layout with puchi.

Nokia 770

November 3, 2006 » Geek

My Nokia 770 came today! This one wasn’t bricked on arrival like the last one. I immediately started in on it, and within an hour I had it loaded up with lots of apps from maemo.org. By now I’ve rooted it and have some scripts set up to handle mounting shares from my network. As a bonus I’ve managed to lock up the application manager, an apt frontend, I think I need a reboot to kill off the process. Lord knows I’m not going to try and kill it myself.

Only a few minor complaints at this point. The handwriting recognition is horrid, but the keyboard has a nice feel to it and you get phone-like word completion. I haven’t tried the fingerboard style yet, rugt now I’m writing this with two styluss (styli?) and I’m actually getting rather fast at it. Maye its th qwerty keyboard.

The other pet peeve came when I wa writing my shell scripts in vi and couldn’t find a way to send the escape key to it. I just now realized that there is a hardware back key that would be a likely candidate. Oops.

Okay, I’m gonna reboot her and see about getting descent or doom running :)

Update (11/03/06)
I got Doom running, how cool is that. This is by far the neatest gadget ever. I need a bigger mem card, then I’ll push the root FS onto the card and I can have it all :)

Nokia 770 Review

October 11, 2006 » Consume, Geek

So I got my Nokia 770 today, or rather yesterday as it is 3:30am now. Here’s my review on this stunning device.

They shipped me a bricked unit. Seriously, I popped in the battery, hooked it up to charge and came back later. It makes cutesy little start up and shutdown noises, but the screen stays white, occasionally adding in some vertical grey lines for variety once in a while.

The Nokia website is useless, and everywhere I’ve found info on the “white screen of death” on the net, it’s led to the same conclusion: Warranty return and replacement. That’s pathetic. You’d think Nokia would have some quality control, maybe, oh I don’t know, see if their devices even boot before shipping them? The boot cycle is supposed to be very short, and I can’t see the production numbers on a device like this being outrageously high. It doesn’t seem unreasonable that they could check it.

What does seem unreasonable is up to another week of waiting for them to ship me a new one. Stupid. If the replacement isn’t stellar and/or they make me pay shipping to send the brick back to them I will assuredly warn everyone I know away from Nokia. And I’ll be sure to get out and meet some people first so it won’t be an idle threat.