Custom Recording Mixer: Part 2

I place my order to BatchPCB.com for channel strip boards about a month ago. They finally arrived last week and I can finally get to make some real progress on this project. I was pleasantly surprised to receive a double order of my pc boards at no extra cost (which is good because I ordered exactly half of what I needed). I was able to spend a fair amount of time putting things together and testing them out this week. I managed to get all the holes drilled in the case and began populating the boards (which look and sound great).

DIY Condenser Electret Mic

For recording enthusiasts and diyers everywhere, there is DiyCondenserMics.com.

Overview:

If you're not afraid of a soldering iron, you can actually build a +48v phantom powered studio condenser mic, for fairly cheap. Most, if not all of the parts can be found at your local Radio Shack. The only thing you really need to find, or make your self, would be the mic body. People have come up with all kinds of ideas for mic bodies. From old flash lights, to pluming parts, to Altoids tins.

The site features build pics, schematics, and construction plans as well as a forum for sharing ideas and other treatsies.

P.S: The move into the new place is going well. ethernet is going in this week, painting is ongoing and a true transformation can be expected in the near future. Pictures to come soon!

Arduino Control Voltage: Rough Code

I've worked a little more on the Arduino Control Voltage. The processing code bellow takes midi input from any midi device, reads the note and velocity information and then spits it back out over the USB Serial connection to the Arduino board. It's a roundabout convoluted way of getting midi information (midi being a serial data stream to begin with), I hope to get a direct midi input wired up soon.
Arduino PWM to CV out circuit

import promidi.*;
import processing.serial.*;

int com = 0; //Comport/Serial port #
MidiIO midiIO;
Serial sOut;
PFont font;
int pit;
int vel;
void setup(){

font = loadFont("ArialMT-40.vlw");
midiIO = MidiIO.getInstance(this);
println(Serial.list());

midiIO.printDevices();

midiIO.plug(this,"getMidi",0,0);
sOut = new Serial(this, Serial.list()[com], 9600);
}

void draw(){
background(255,255,255);
textFont(font,15);
fill(0,0,0);
text("Midi Data",0,14);
textFont(font,12);
text("Note:",0,28);
text("Velo:",0,42);
textFont(font,12);
text(pit,42,28);
text(vel,42,42);
}

void getMidi(Note note){
println("Got a note!");
vel = note.getVelocity();
pit = note.getPitch();
println(vel);
//println(pit);
sOut.write(vel);
sOut.write(pit);
}

Bellow is the (now) simple code to be uploaded to the Arduino board which just reads the serial data and controls the PWM output.

/*Arduino CV. Reads note and velocity information form the serial line and outputs to PWM pin */
byte note = 0;
byte vel = 0;
int synPin = 11; //Pin # for pitch CV output

void setup() {
Serial.begin(9600);
}

void loop() {
if(Serial.available() >= 2 ){ //Wait untill there is enough information
Serial.println(Serial.available(),DEC);
vel = Serial.read(); //FIX ME: Implement velocity sensitivity (VCA Control)
note= Serial.read();
analogWrite(synPin,note);
}

}

Arduino Control Voltage by Dana Simmons is licensed under a Creative Commons Attribution-Share Alike 3.0 United States License.
Based on a work at code.google.com.

First revision: Arduino Control Voltage

The recent holiday brought into my possession a shiny new Arduino Duemilanove board, my first real project with it? Control Voltage output to control my self titled Uranus synthesizer (based on the Voice of Saturn synth). In any case, after a couple long nights I cam up with the sketch bellow, I've tested it and it seems to work with a little adjustment from the pot on the output.

I have yet to attempt at getting the thing tuned, but by runing the PWM output of the Fading sketch (a steady ramp up and down from 1 to 255) i was able to verify that it does indeed control my rather excentric synth. Thoughts, suggestions and critics welcome.

NOTE: The capacitor in the lowpass filter at the bottom is 470 uF, apologies for not adding the value.



Arduino Control Voltage by Dana Simmons is licensed under a Creative Commons Attribution-Share Alike 3.0 United States License.
Based on a work at code.google.com.

Build Pics: Home LAMP server

As promised, I've uploaded some pictures of my latest project: A home network LAMP/Backup/Print server. Details on configuration and ub3r tweaks next time.

I chose a micro ATX case, for slim compact size

Time to roll up the sleeves and get dirty!

It's a GeForce 7050M Motherboard

The three hard drives which will handle all the data (two 500 gig sata, one 80 gig ide)

One of the two drive trays to hold the RAID 1 array

It's coming together!

Installing Debian. (Before I realized it was much simpler to do a net-install via usb flash drive)

And that's that. This little workhorse has proven to be a very valuable investment. Besides backing up my main workstation every night to the RAID 1, It runs TorrentFlux to manage bittorrent downloads and also servers as a CUPS host to my home network for printing.

Prelminary descrete circuitry guitar amp.

Above is pictured a very simple and wonderfully bad guitar amp circuit. The output is weak and horribly distorted but it works and can sound quite interesting.

After doing more research I noticed a striking similarity to my circuit and an NPN based Fuzz Face circuit

Headphone/Monitor Switch in a can

Frustrated with having my monitors and headphones amp on separate outputs. I cooked up this wacky and simple switcher to select where to send the main outputs from my desktop workstation P.C.

Basically it is just a DPDT switch wired up to a set up 1/4" TR inputs, fed from outputs 1 and 2 of my sound card. The switch can either trow the signal to the headphones amp or the monitors. I simply grabbed the closet empty semi rigid container I could find  (I.E: empty soda can) to house the wiring and such. In the pictures below I've only completed 2/3 of the wiring as I still have to add a second set of outputs (I ran out of female 1/4" TR plugs). Thus, in it's current state it simply acts as a glorified on/off switch. Once I get some more TR plugs I'll put it all in a proper enclosure and it will find a happy home on my desk. Build pictures bellow.

I scavenged some 1/4" female plugs from an old mixer. Bellow are all the build materials (minus two female TR plugs of course)

Here is the can with the holes punched out, I just used a flat head screwdriver and a little ub3r skill to cut "X"s in the aluminum, then simply folded the corners in.

Soldering the TR plugs:

Inside the can after all the TR plugs are installed

After the switch gets installed

And finally 2/3 of the finished project

Phillips Scope Repair (Done)

Like the title says, I've been able to successfully repair my PM3217, with a lot of help from a friend. Turns out there was a broken strand of wire that was part of an induction coil in the vertical amplifier, after a quick re-solder the C.R.T is fully functioning. The next step was to recalibrate the beast. I managed to find a service manual, which included the much needed instructions and schematics for the process. Several nights of tedious measuring and adjusting and everything is back in order. The finished product is pictured bellow, not a bad deal for $60 odd bucks on ebay after all.

Phillips Scope Repair

I finally decided it was time to buy an oscilloscope. I ran across a Phillips PM3217 on ebay for what seemed to be a good price, the seller couldn't test the thing because "he didn't have any probes", so it was offered as is. The two traces were confirmed to at least display and move about, "what could possibly be wrong with the thing", I thought. So I get it in the mail and the first bad sign is a notable rustle of what sounds like something broken. I open the shipping box and the front cover, which is supposed to protect the front panel controls, has been shattered into many plastic pieces. Also, the distinct smell of burnt electrolyte fills the air.

Long story shortened, There was a blown capacitor on the power supply and the trace could only be displayed in the bottom third of the CRT screen. *sigh* Lessons hard learned: Taking risks on eBay is rarely worth it.