Intro: Intro to Analog Synthesizer
Welcome to the How to Build a Synthesizer, beginners guide to the things you will need to know in order to build an analog synthesizer.
Background on the project - During our senior year at our school all seniors are afforded the opportunity to work on a project of their choosing for two trimesters. During this time we are expected to work to a standard of professionals in our field (or area) of choice. Some of the projects range from teaching Physics, creating musicals, and preparing for the Zombie Apocalypse. While there is an almost limitless amount of projects that one can do, one caveat is that the projects must help someone besides ourselves (more on that later). For our project we have decided to work together to build an analog synthesizer. By doing this we are combining our love of both electrical engineering and music into one project. And now we want to share what we have learned with you.
Why did we do this? - Even before this project we have both enjoyed the the thought process behind (though admittedly toned down version) Electrical Engineering from Maker Fair winning near space balloons to underwater ROVs the electronics of things has always fascinated us. With this we wanted to build a Synth outside of school, unfortunately to our annoyance there seemed to be no good online guide in order to help us along. When Senior Signature Projects (SSP) came along we then made it our goal to alleviate this by providing a easy to follow instructions on how to do what we did.
What we hope people get from this project - As a result of this we hope that you are more comfortable with the finer points on analog electrical compo nets, what they do and how to use them. Though we don't pretend to make you an expert at any one thing, we hope to lay the ground work and show you how to build a synthesizer from beginning to end.
Throughout the process we used Make Analog Synthesizer (MAS), while it is not required that you use this book while going through this guide MAS is a very good source we would recommend it for further reading. Further reading (including MAS) will be suggested at the end.
We would like to thank our mentor Tom Oberheim, your help and encouragement was invaluable.
Step 1: Basic Components
In order to move forward with this project there are a few terms that you should know...
What is a synth?* (should we have this? if someone is researching how to build a synth, they probably know what it is)
Here are a list of basic components that we will use and you should know...
Resistor - A resistor is an electrical component that reduces the current and voltage going through a circuit. Units of Resistors are measured in ohms (Ω) and typically range from 1k to 1M in our setup (There are a few exceptions).
Resistors are color coated, the color code diagram for Resistors can be found here: http://www.digikey.com/~/media/Images/Marketing/Re...
Capacitor - A capacitor is a component that stores energy. Capacitors are typically measured in Farads or Micro Farads (F and µF respectively)
Capacitors can come in multiple forms, though they will (excluding surface mounted Capacitors) look like this.
Transistor - A transistor is a semiconductor used to amplify and switch electrical power. There are two types of Transistors, Bipolar Transistors and Field Effect Transistors. A Bipolar Transistor will have three leads, the collector, the emitter, and the base. A Field Effect Transistor will also have three leads, but they are called drain, source, and gate instead.
Diode - A diode is a semiconductor that makes it so electricity can only flow one way.
Op-Amp - An Operational Amplifier (Op-Amp) is a device that has two inputs (labeled (+) and (-)) and one output. If the (+) input is a higher voltage than the (-) input, the output is a positive voltage. If the (+) input is a lower voltage, then the output is a negative voltage. These components are usually used as oscillators (generating a repeating waveform) or comparators (judging which input has a higher voltage).
Step 2: Basic Concepts
Here are some basic concepts that you should know before attempting something like this. While you may not use each one of these concepts everyday for every step having a basic understanding of each of the following might prove to be helpful.
What is electricity? Electricity is the flow of electrons (which are negative) from one space to another.
What is ohm's law? Ohms law shows how to solve for electrical current, resistance, or voltage. In the base form of the equation the formula states that the eletrical current (measured in Amperes) is equal to the resistance (in ohms) divided the voltage. While the equation is solving for I (Electrical Current) the equation can be manipulated to solve for any of the other values (R or V).
Here is a good representation of the may different versions of the formula,
Here are some good practice problems,
Equation: I = V/R
I = Electrical Current measured in Amperes (A)
R = Resistance measured in ohms (Ω)
V = the voltage drop of the resistor
What is a multimeter, and how does one use one?
A multimeter is an electrical measuring instrument that normally combines multiple measuring functions into one package. The leads of the multimeter need to be connected to different outputs to perform different measurements.
Some of the basic measurement include,
This is the multimeter that we used, notice the outputs and the units near the outputs.
While you may not need the multimeter for every step, it can prove to be a useful tool for figuring out what is wrong.
When is it useful?
Using a multimeter is useful when you need to measure something, such as I, R, V. Another example of a use for a multimeter would be checking the connection between two points, checking to see if you have successfully made a connection. In this situation checking if you have soldered the points together can save you a lot of time when trouble shooting.
Step 3: Building Process: Breadboard
What is a breadboard?
A bread board is a prototyping device that one can use to create an electrical circuit, it is primarily used during the prototype phase because it is easy to create and change. One would not use a breadboard past the prototyping phase because it is less permanent, soldering it it to a circuit board (like in the next slide) would be a better solution.
How to breadboards work?
Underneath the rows and columns of a breadboard are metal strips that conduct electricity. The metal strips are isolated to each of the rows and columns.
The underside of a breadboard can be seen here,
Step 4: How to Solder?
What you will need:
You will need a soldering iron of decent quality. Temperature control is not a necessity, but can be helpful. For solder, you can use either lead or lead-free solder. Lead solder has a lower melting point, but lead-free is safer. A damp sponge is also useful, for cleaning the tip of the soldering iron.
You will spill solder, or drop your soldering iron at some point, so make sure to work on a table you don't care too much about or get a plank of wood to work on.
- Allow the soldering iron to heat up beyond the melting point of the solder.
- Wipe the tip on the sponge, apply a little solder. The tip should now be silver.
- Place the tip on the metal pad of the PCB, touching the wire you want to secure as well.
- Place the solder on the other side of the wire, touching the pad. Add more solder until it flows around the wire.
- The solder should slope up to meet the wire, instead of bulging out. If the solder is not shiny, then you may have a cold solder joint, which you can fix by heating up the pad or the wire more.
If you find that the tip of the soldering iron is not conducting heat very well, or has turned black, you can use a Hakko 599b tip cleaner.
Work near a sink, so you can keep your sponge wet, and can quickly get your hand under water if you burn yourself.
Use thinner solder, to better control how much solder is put in each joint.
Step 5: Building Process: Circuit Board
For a more build that is more permanent than a breadboard, you can use a solder board or a specialized PCB. A solder board can be more versatile (as you get to decide where all the electrical connections will go), and you can even buy one that has the same layout as a breadboard, requiring very little adaptation of your circuit design. However, a specialized PCB will require less work to solder, and making multiple copies of your circuit will be easier.
Dry-fitting (placing without soldering) our components was not difficult, because the solder board we used had the same layout as our breadboard. Dry-fitting is important, so you don't solder yourself into a corner. In our project we had to solder ~200 joints, so getting all the joints correct the first time was crucial.
Step 6: Further Reading and Image Citation
If you interest in this you could read the following,
Make: Analog Synthesizer