USB Audio Project

My <$10 (Canadian) USB Audio Adapter came in today. I got it from www.ledshoppe.com, it took about 2 weeks for delivery, no customs charges, shipping included. And of course I opened it up. The chip inside is not labeled and there are no drivers provided (it uses native windows drivers). Upon lots of googling I found the software and it identified the codec as a cmedia CM108. I found the datasheet and have confirmed that it is a CM108 (probably a black market knock off but it works). The device has audio output (low power, shitty onboard amp) but it also has many other features which I plan on implementing in hardware. Most notibly it has SPDIF out so I can connect to an external receiver. The software support is there so you just have to attach the wires. Also it has I2S output so it can easily be connected to a better quality DAC.

My first project though will be to add a better power amplifier using the existing DAC, I'm going to make a USB powered CMOY headphone amplifier. I've sampled some DC/DC converters from TI to generate +-12V (2% ripple) for the OpAmp voltage rails. They're $10 each but their nice enough to sample them for free. The part numbers are PT5024 and PT5041. They're capable of providing much more power than the headphone amp could ever need. The usb port can provide 500ma at 5V (2.5W) which should be more than enough power this application.

All this for what purpose you ask? Well laptops/iPods/etc suck at amplifying, they have low rail voltages and high distortion figures. So the plan is to start by adding a better quality amplifier onto the output of the device (prevents the device from distorting as much due to high impedance load, and provides a more powerful output). Eventually I want to add a better quality DAC to the device as well (using the I2S output)

Projector Update

Well parts have started coming in, I now have my 5" LCD display partially disassembed, (pics coming soon), I also have my Fresnel lens's. I'm still waiting on my Metal Halide bulb and balast, hopefully they will be coming soon. I havn't been able to find a spherical reflector for the bulb yet, hopefully I can come up with something this weekend.

Blast from the past

I saw this and laughed my ass off, storage for the low price of $166 per Mb. If that were still the price today my storage at home would be $66.4 Million dollars! 

How to download via binary newsgroups

So lots of people are interested in how to get software from binary newsgroups efficiently and quickly. So I've decided to put together a how-to of how I do it. There are tons of ways but this is the way I've found to be most efficient.

Overview: Use an indexing service to get find the software/movies you want. Get a .nbz file from the indexing service (contains a list of the posts you need to get from the server to get the software/movies you want). Open the .nbz file in a newsgroup downloading program, after the files have been downloaded to your machine run a parity check to repair any damaged/incomplete files, extract files as required.

Indexing Service: Its easiest to use an indexing service to browse the newsgroups, I use www.newzbin.com, its very easy to navigate, and indexes all the newsgroups I need. You have to pay to be able to use the useful features (downloading .nbz files) but its well worth it.
The most efficient way to use this service is to bookmark all the posts you want to download then download a .nbz (spool file) of all of the posts bookmarked.

News Reader: This is an application that you will use to open the .nbz file. It uses this spool file to download all of the posts you selected using newzbin. I use GrabIt www.shemes.com, there are probably better programs out there but this one works for me. So once you get it installed, and setup with your news server (dependant on your ISP) just open the .nbz file you downloaded.

Parity Checking: Most posts include parity files so that missing parts can be rebuilt and errors can be fixed prior to extracting the archive. I use quickPar www.quickpar.org.uk.

Extract the file: Use winRar or similar to extract the archive.

VNC over SSH

I've been searching for a remote access solution that suited my needs. I've decided to go open source and use VNC. As you may know VNC is not secure. Packets can be easily intercepted and keystrokes etc. can be filtered out. So I decided to tunnel the VNC traffic through SSH to my host machine. There are some how to's floating around but it was pretty straight forward. I'm also looking to tunnel all of my internet traffic over SSH to my local machine so I can surf securely from hotspots.

The basic premise of this setup is to establish a SSH session with your host machine (a WinXP box in my case running Cygwin w/OpenSSH) using Putty (or openSSH). Setup putty to redirect all calls to a partical port on your local machine to be tunneled to through SSH. VNC to your local machine with the port specified so its tunneled to your remote system.

VNC over SSH Diagram

VNC over SSH Diagram

Projector

I'm in the process of building a digital projector (something similar to this http://www.diyprojectorcompany.com/). I'm looking to make mine as cheaply as possible but with decent quality output. Check out the latest details:

Light Source: I've going to be using 250W Double Ended HQI Metal Halide light source (http://www.diyprojectorcompany.com/catalog/product_info.php?cPath=22&products_id=49). I bought it used. I have to get a sperical reflector to go behind the lamp.

Pre LCD Light Path: I am currently trying to determine what focal length of precondensor lens to use. The condensor lens from my slide projector is the wrong diameter so I have to figure out what to do next. I will also need to install some IR glass so I don't cook my LCD with my fancy new light.

Fresnel Lens: I'm still planning on using my cheap 5" fresnels to start, I'll move to someting better as needed. If I move to a split fresnel setup then I can implement optical keystoning so I can mount the projector from the ceiling if I decide to.

Mirror: I'll need to find a first surface mirror at some point so I can fold the light path so I don't have to make a stupidly long projector. I'll probably use a standard plain mirror to start.

Triplet: I'm going to try to use the triplet that came with my slide projector to start. It will give me a 105" projection. I'm really leaning towards spending the money and getting a 220mm focal length varifocal lens to make it easier (possible) to focus. It will give me a 55" diagonal projected image in the room I'm planning on using the projector in.

First Post

The purpose of this blog is to give me a place to share the details of my projects. My current projects on the go are a Digital Video Projector and a Personal Video Recorder (PVR - Its like a TiVo). I'll be moving some posts from my personal blog (http://gtscanada.com/blog/) to this blog.