HEAD LAMP!

I finally bought a sweet headlamp for myself! This amazing gadget has two settings, one super bright 3 white LED setting for working on electronics, and one super cool red LED setting for when I want to look like a cyborg! CROSS THIS ONE OFF MY WISHLIST!

CIRCUIT GUIDEBOOK

Now that most of the basic vocabulary is out of the way, there have been less posts, but I am still busy as ever!

I am currently reading this amazing book "electronic music circuit guidebook" that my friend Jeff just let me borrow! The book is not written with the amateur in mind, and some of the material is dated, but because I have done so much research over the past month, I can understand what they are saying and it rules! It basically has the schematics for each part of a complex analog synthesizer. This book is helping me understand the greater possibilities that I can achieve with signal generators!

SQUARE WAVE GENERATOR

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Here is the schematic for my first finished signal generator! I am really excited to finish my first project within a single month! I learned LOTS of things with this project!

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COMPONENTS LIST:

9v Battery
SPST Switch (On/Off Switch)
SPDT Switch (Settings Switch)
MOM (ON) Switch (Push to Make)
IC1 - 7805 5v Regulator
IC2 - 40106 Hex Inverter
C1 - 0.1uF Capacitor
R1 - 100K Potentiometer
R2 - 100K Potentiometer
R3 - 10K Resistor
Output - 1/4" Audio Connector




HERES MY FIRST RECORDING WITH THE NEW SIGNAL GENERATOR!

SWITCHES

SWITCHES give you control of your device. They dont need any power to operate, so you can place them anywhere in your circuit to control where the power goes. These are some basic symbols of types of switches we will be using in our circuits. They have their own vocabulary of terms to describe how they work.

The most basic is the ON/OFF SWITCH. These are placed near the positive charge to cut off power at the source. ON creates a CLOSED CIRCUIT and OFF creates an OPEN CIRCUIT.


PUSH TO MAKE SWITCH is a button. When it is pressed down it closes the circuit, when released the circuit becomes open and the power turns off. It is called a MOMENTARY SWITCH. A button like this is used to make doorbells.





PUSH TO BREAK SWITCH does the opposite, when pressed it opens the circuit, when released it closes the circuit. It is also a MOMENTARY SWITCH. We are going to use one of these to create a silence button on the output of the oscillator, this way we can silence the speaker while switching to another frequency. This will give the oscillator a much wider range of uses when we are making music!



A MULTI WAY SWITCH can switch between different settings, on the oscillator it will be a knob. We are going to use one of these eventually to switch between different types of waves (sine wave, square wave, and triangle wave) and also to switch between different frequency ranges (100, 1K, 100K).





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INVERTER (IC)

INVERTERS are a type of integrated circuit, so they are abbreviated IC even though they have a different symbol. An inverter is also called a LOGIC GATE because it uses a simple logic program to invert the signal coming into it. If the signal coming in is 0, it changes it to 1, if the signal coming in is 1, it changes it to 0. If you connect the output to the input, you have a rapid oscillation between the two values!

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GROUND

GROUND represents a point of 0v. In larger circuits it is the actual ground, but on our projects it's just the negative battery wire. This symbol shows up because its easier to write this than produce a wire going to the negative battery wire on schematic. Even if they are disconnected in the drawing, they are all actually connected together when building your circuit.

INTEGRATED CIRCUITS (IC)

INTEGRATED CIRCUITS (IC) are miniature electronic circuits. They are housed inside a DUAL INLINE PACKAGE (DIP) which has pins linked to the chip inside. The pins are numbered counter clockwise from the top left, and the top can be discovered by looking for the half circle indentation on the component. These are really sensitive, and if you are soldering you need to use a DUAL INLINE SOCKET (DIL SOCKET). Its basically another plastic component with pins to solder to the board and pin holders that you can just push the IC into when you are finished.

Sometimes there are other labels on the DIP besides number. These do not effect the numbering system, so they replace the number and the pin count remains the same. So if pin 1 was labeled VDD, pin 2 would still be pin 2, not pin 1. Here are some common alternates:

VDD - positive supply
VSS - ground or negative supply
GND - ground or negative supply

ICs are designed to be placed over the cooling area on the breadboard, connecting columns E and F together. This is a photo of the Hex Inverter IC used in the first project.

DIODES (D) + LIGHT EMITING DIODES (LED)

DIODES (D) are components that allow electric current to flow in only one direction, the direction of the arrow on the schematic. The forward direction is the ANODE (A) and the reverse direction is called the CATHODE (K). They have to be connected the right way around or they clearly wont work, but an actual diode has a line signifying the anode on one end to make this easier.

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LIGHT EMITTING DIODES (LED) are type of diode which emits light when electric current passes through them. They are awesome! There are two wires that hang off every LED, the longer one is the anode and the shorter one is the cathode. Like any diode, they have to be connected in the right direction in order to work. LEDs need to have the correct amount of voltage running through them or they burn out. A standard red LED uses 2.0V and .02mA.

To work out what type of resistor to use in your circuit, use this variation on Ohm's Law:

R = (V_S - V_F) / I

• V_S= Supply Voltage
• V_F= LED Voltage

So if the supply voltage (V_S) is 9V in our circuit, and we are using a single red LED which uses 2V (V_F) and needs 20mA (I) we would need a 350 ohm resistor.

• (9V - 2V) / 0.020A = 7V / 0.020A = 350 ohms

It's better to overestimate resistance rather then underestimate and blow your LED, so use the nearest standard value which is higher. In this case, that would be 390 ohms. Don't forget that resistors have a tolerance value, so use that to fall within the range you need!
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OHM'S LAW (V = I x R)

This formula is going to be super important as we try to build our own circuits and need to determine the correct component for our schematic:

VOLTAGE (V) = CURRENT (I) x RESISTANCE (R)

• V= I x R
• I = V / R
• R= V / I

VOLTAGE is expressed in VOLTS
CURRENT is expressed in AMPS*
RESISTANCE is expressed in OHMS

• volts = amps x ohms
• amps = volts / ohms
• ohms = volts / amps

A trick I learned to remember this formula is to think of each letter as an animal (vulture, iguana, rabbit). The vulture is flying above, and the iguana and the rabbit are below.

• To the Vulture, the Iguana and Rabbit are at the same level. (V=I x R)
• To the Iguana, the Vulture is above the Rabbit. (I = V / R)
• To the Rabbit, the Vulture is above the Iguana. (R = V / I)

*mA = MILLAMP = 1/1000 amp = .001 amp

RESISTORS (R)

RESISTORS obstruct the flow of electric current. They have no polarity (+/-) and can be connected either way in a circuit, so you can't really mess them up. For most of my projects, they are used to control the pitch of the oscillator. The resistance value is measured in ohms. The tolerance is the degree of sway from the value listed. Electronics aren't perfect.

You can identify the resistance and tolerance value from the color bands on the side of a resistor. The first band represents the first digit of the number, the second band represents the second digit, the third band represents the multipler, and the forth band is the tolerance value. For example, a resistor whose first band is yellow, second band is violet, third band is orange, and last band is gold would have a value of 47K with a tolerance of +/-5%.

1. FIRST DIGIT
2. SECOND DIGIT
3. THE MULTIPLIER
4. THE TOLERANCE

Here is a chart I made which explains what each color means. The colors are arranged chromatically, with darker colors having the lowest value and lighter colors have the highest value. Metallic colors go into decimals, with gold being the best, and silver being second.
















Resistors come in really strange values because they work within the tolerance percent ranges, because of the these ranges there isn't a need to make every value of resistor. There are two different series of resistors, but they both repeat in multiples of 10 for higher values.

The E6 series has six values : 10, 15, 22, 33, 47, 68
The resistors from this series all have a 20% tolerance value.
The values go up roughly 50% between each increasing value.

The E12 series has twelve values : 10, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82
The resistors from this series all have a 10% tolerance value.
The values go up in smaller increments in this series to compensate for the lower %.

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This is the symbol for another kind of resistor, a variable resistor or POTENTIOMETER. Really, this is just a knob that you can turn to change the amount of resistance going through a circuit. Different types of potentiometers have different ranges, but they are rated according to the maximum potential value.

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