ewi-analog-synth

Design and test of mouth-controlled polyphonic synths

Now developing the surdboe.

A good friend of mine told me its sound was similar to that of an oboe, but with a mute on it; thus, I thought that the french sourdbois could be a good name for it.

A brief style guide for OCD purposes

This repositories serve the purpose of registering my (until now dream-like electro-musical projects (special thanks to the collaboration of beloved friends); in particular, windelec is oriented to those of a blowy kind. In this guide, I will list the different type of files that you will find and how to work with them properly (that is, cohesively).

The workspace for hardware to be used: LTSpice

LTspice XVII is now out! Well, as it was three years ago... (still, yay!).

This is the software I have been using for modelling whatever I had in mind (excuse me, I lack both the money and the patience to use OrCAD). So far I cannot complain: it is quite fast, almost fully customizable (colors, fonts, key bindings...), and really a light-weight option. Analog Devices (+LT) does supply this with a huge ton of models you can easily import, and it is really easy to create your own hierarchical blocks and symbols, so I am in love with it. You can download the thing here. The LTWiki is actually my main source of knowledge about the software, so I will drop a link here too.

So, let us start with the basics about drawing circuits here (list subject to changes):

First of all, we need to know the file extensions we are working with. There will be, at least, four of them in any circuit diagram we create and simulate: .asc files (LTspice Schematic), .asy files (LTspice Symbol), .raw files (simulation plot data) and .log files (error-like messages). Out of these four types, the ones that really matter are those containing schematics and symbols, so there is no need for GitHub to take care of the other files (we will talk about LTspice Netlists after this section). There is an easy way to exclude these files from taking a piece of the folder: after opening LTspice XVII, go under the tab named Tools and tick down the path "Control Panel > Waveforms > Directory for .raw and .log data files > Store .raw, .plt and .log data files in a specific directory". Choose, of course, a folder outside the domains of your local repository, and voilà. I highly recommend storing them in a folder following the path "C:/Users/[username]/Documents/LTspiceXVII/simresults".

Regarding LTspice Netlists (.cir extension): they are useful for adding new components to your workspace, but can be deleted after doing so. Please, do not upload (exclude them from the "git add" command). Also, you can explore the "Control Panel" for further options (like changing font and color scheme, methods of integration...). It would be wise to change the "Waveform Plotting Thread Priority" from medium to high, under the Operation tab.

You can change the keyboard shortcuts under the tab "Drafting Options", clicking on "Hot Keys".

1. We will be using (always) resistors res2, and transistors npn and pnp, for aesthetic purposes. I do not really like the other models. Plus, when you have placed at least one component of each kind, the rest are copied out of that one; there is no need for accessing the library each time. The models and values for each component can be chosen right-clicking on them. We will take special care over the names: a component has a number on the sheet deduced from its distance to the input signal he receives and the resistors that precede it. For example, if a circuit has three input signals and they merge together at a common output, the resistors will be named R11, R12, R13... and so on on the first branch; R21, R22, R23... and so on on the second branch; and R31, R32, R33... and so on on the third branch. The branches and components are numbered up to down, and so the first number of that resistor names the branch (void if there is only one signal way), and the second number its distance from the origins. The shorts for the main components are: R (Resistor), C (Capacitor), L (Coil), OP (Operational Amplifier), D (Diode), Q (Bipolar Transistors), J (JFET Transistors), M (MOSFET Transistors).

2. The placement of a component, or a number of them, between two nodes must always be symmetric. This needs no further explanation, just keep them centered for highlighted readability.

3. Grounds should all be at the same height (if possible), and there is no advantage in connecting more than three wires to the same ground - just create a new ground and align it.

4. Names displayed in caps are meant to be constant values, while those written in lower case are usually signals or values subject to changes. So we consider VBat to be a c.c. value, while vin is clearly a time dependent signal.