New Adventures in Physical and Virtual Systems Design

This week I decided to jump ahead a bit to delve into the third section of the book dealing with basic electronics.  I had scheduled a meeting with Don Johnson who is well versed in electronics and I wanted to mentally prepare myself for our meeting.  The three chapters that I read dealt with semiconductors, diodes and power supplies.

I was especially interested in the chapter on power supplies since I was seriously thinking about building my own power supply for my Blacet rack.

I met with Don Johnson on Monday, October 26^th of week five.  He is an extremely knowledgeable man regarding mathematics and electronics.  We discussed logarithmic scales and power supplies.  I quickly realized that perhaps the best course of action for now would be to purchase a power supply and wait on a power supply build for the time being.

While poking around in the library recently, I found a book on designing and building power supplies from the TAB electronics serious as well as a handbook on troubleshooting electronics.  I think both texts will be of interest in the near future.

This week, my focus was on getting more functionality out of my modular synthesizer build.  I completed a front-end mock up my rack and how I wanted various modules to interact with each other.

Next, I started taking some of my individual patches and putting them together into a single modular synthesizer patch.  This sounds easy, but each step is a rather time consuming process.  I managed to get a rough sine wave oscillator into a filter and out to an amplifier.

I have been reading the online tutorials from Cycling 74’s website and they have been very helpful.  I read through a five-part article on a guitar processor build that was really amazing.  I’m thinking about doing some reverse engineering to get a slicker front-end look and see how one can chain multiple modules together into a useable network.

The next big step is a 16-step pattern sequencer routable to the oscillator and filter modules.  I would also like to be able to send a pulse out to trigger envelope generators as well.

This week went really well with the soldering.  I got a chance to look back at my first build and compare the solder joints from the previous week to this week, and saw a lot of improvement.  In fact, I’m a bit surprised that the confidence boost even worked.

I started my session by checking the parts against the parts list and testing needed parts with my multi-meter.  Checking the colors or resistors is always a bit difficult, even with good lighting so the multi-meter really came in handy.  I completed most of the soldering in two sessions.

I am currently looking for a 95 – 99% alcohol solution such as isopropyl alcohol or grain alcohol to clean the flux off of the printed circuit board.  I’m using no clean solder, but it is still suggested that one clean the traces and residue on the board.

Next week, I will wire up the pots, switches and hopefully give it a test run.

The Discrete Fourier Transform

From chapters one and two, Lyons launched into hyper warp drive with the discrete Fourier transform.  Lyons states in his book that

The DFT enables us to analyze, manipulate, and synthesize signals in ways not possible with continuous (analog) signal processing. (Lyons, 45)

This interests me since I am currently studying analog synthesis techniques and use voltage controlled modular analog systems, which happen to have some limitations.  My question concerns how to apply these wonderful processes to create complex signal processing systems.

I am certain that out of this confusion will come some brillian revelations because generally when one tries to comprehend complex sytems too quickly, one does not fully fathom or appreciate their usage.

For week three, I jumped into Part II dealing with alternating current basics.  The following three chapters dealt with alternating current basics, inductance and capacitance.

The ninth chapter on alternating current basics was interesting in that the chapter mainly dealt with waveforms.  This has been the common thread through everything I have been reading.

Chapter ten dealt with inductance.  I think this chapter would help in the design of a nice, beefy power supply.  Generally inductors are used in analog circuits and signal processing.

The eleventh chapter on capacitance was immediately useful.  The Confidence Boost pedal I build used several capacitors in the circuit and this chapter helped explain what they were used for.

For the past two and a half weeks I have been working through the tutorials in MAX/MSP and building simple oscillators and signal processors

During week two, I had set out to create several signal processors since I had been mainly focusing on building oscillators and wanted to try other things as well.  My finished builds consisted of a tremolo/ring modulator, a low pass filter.

For the tremolo/ring modulator patch, the source wave consists of a triangle wave and can be modulated with either sub audio modulating frequencies or audio modulating frequencies of various tones.  Variables can also be changed within the number box.

The one pole low pass filter uses a sample as the signal source and has an adjustable slider to change the cutoff frequency.

For week three, I spent half of my time developing more complex oscillators and a multi-delay unit.  Pictures will be forthcoming.

My current goal is to take these many projects and use them as sub-patches that make up a larger patch.  This will consist of an oscillator section, a filter section and envelope section that will be user friendly and highly configurable.

onepolelopasfilt

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For the past three weeks, I have been running around like mad collecting equipment to prepare for the physical build section of my contract.  I found a space with a workbench and good lighting where I can leave my project undisturbed and come back to the work when I am ready which is really nice.

For the first build, I am in the process of making a BYOC (Build Your Own Clone) Confidence Booster circuit to get my feet wet so to speak.  The circuit consists of a linear boost and buffer with either mono or stereo input/output.

To start, I completed a parts count, and tested all the resistors with my multi-meter to make sure they were the correct value and were working properly.  Thanks to Stan Gibilisco and his chapter on resistance I understand how the resistors work in this circuit.

On Tuesday, October 13, 2009 I finished soldering all the resistors.  I attempted to take some photos for documentation purposes; however, my digital camera is not able to take close up photos so I am working on other possibilities for using photos to document my build as it progresses.

I just want to say that this book is really great.  It is by far one of the most technical books I have read in a long time, which has made me go back and read each chapter twice, but I am getting a lot of mileage out of Lyon’s text.

The second chapter on periodic sampling really helped me understand the frequency-domain ambiguity that is associated with discrete-time signal samples.  When we are sampling a given frequency, the sample rate can cause the sampled signal to become indistinguishable from another signal that may also be able to pass through the points of the discrete sequence.

The rest of the chapter discussed techniques and the calculations involved in sampling low-pass signals and sampling bandpass signals.  Lyons demonstrated how analog low-pass filters could be used to focus on the signal of interest thus cutting out noise on either side our source signal.  I found the last half of the chapter on sampling bandpass signals very in depth.  I’m still still not clear how this could be applied to MAX/MSP patches, but I am getting a solid foundation in the theory behind digital signal processing.  Lyons quotes the Greek mathematician Menaechmus at the beginning of his book as stating to Alexandar the Great:

There is no royal road to mathematics.

So I am content to make the journey of the great hill to find an occasional small plateau to rest and then resume  my journey.

This week, the reading focused on direct-current circuit basics, direct-current circuit analysis and lastly resistors.

I found the fourth chapter on direct-current basics really useful as it introduced me to Ohm’s Law and provided real world practice using number calculations that solve for voltage, current and resistance.  This chapter also provided me with a refresher on schematic symbols.  The practice has already come in handy as I make preparations to start building my envelope filter pedal.

The sixth chapter on resistors was the most immediately useful chapter as of now.  It helped me understand what role resistors play in circuits design showed me how to read resistor specifications when reading the Ohmic value, tolerance and the power rating.  By far the most useful suggestion given to me was to check each resistor with an Ohm meter before installing it into a circuit to avoid mislabeling or defective parts when putting together a build.

As I become more comfortable with electronics, I believe this book will give me the foundation necessary to start designing and testing my own circuits.  I am already getting very comfortable with reading schematics and performing calculations with Ohm’s Law.