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electrical engineering notes

i never studied electrical engineering, and generally am a complete novice.

below are some notes i've been taking as i learn. i'm also taking notes on

specific [integrated-circuits] while learning about making a

[diy-synthesizer].

laws

ohms law

I = current (amperes)

V = voltage (volts)

R = resistance (ohms)

I = V / R
V = I * R
R = V / I

faraday's law

predicts how a magnetic field will interact with an electric circuit to produce

a electromagnetic field, which is, electromagnetic induction

The electromotive force around a closed path is equal to the negative of the

time rate of change of the magnetic flux enclosed by the path.

units

Voltage (volts): electric potential difference
Ampere (amps) = electrical current
Ohm (Ω) = electrical resistance
Farad = capacitance of electrical potential
K = shorthand for 1000 Ohms often

* also 2K8 means 2800 for example

components

diode

one side has no resistance, other is infinite (ideally).

they ensure current flows in one direction

cathode - short leg: negative end

anode - long leg: positive end

light emitting diode (LED) - converts electricity into light

resistor

resistors simply resist current! then converts current into heat.

resistors are made out of insulators and conductors.

more insulators is equal to more resistance.

resistors have stripes on them. read about the [electronic color code].

resistors also can serve as heating elements.

if you think about a toaster, or a hair dryer, they function by means of the same mechanism as resistors.

*water analogy**: smaller pipe = bigger resistor

capacitors

stores electric charge in an electric field. it is :

electrolitic capacitors are bigger - they are polarized.

cermaic capacitors don't store very much charge - not polarized.

*water analogy**: a bucket that empties when full sorta?

potentiometer

a three terminal resistor.

there is dial against a graphite disk

the more graphite that it has to go through, the more resistance.

the pivot point is connected to the middle.

side pins are the opposite sides.

the terms are called:

nose of the potentiometer (middle)
cheek of the potentiometer (ends)

integrated circuit

a specific set of capacitors, inductors, transistors, resistors in a circuit.

these look like small "chips". "living bug" position refers to it being with

its legs down. and the flat part is at the top.

the pins on an IC have numbers like so:

10 9 8 7 6
 | | | | |
|----------|
|\         |
| |        |
|/         |
|----------|
 | | | | |
 1 2 3 4 5

where the left side has a marker like a half circle

voltage divider

passive linear circuit that reduces voltage from its input to its output
one way to create a voltage divider is to use a potentiometer - a resistive divider
If you set up two resistors - VoltageOut = Resistance2 / (Resistance1 + Resistance2) * VoltageIn

BJT

biopolar junction transistor
uses the language of:

* emitter

* base

* collector

FET

field effect transistor
uses the language of:

* source

* gate

* drain

VCC VEE VDD VSS

terms for various voltage supplies on schematics

Negative Voltage Supplies

* VCC: Voltage Collector Collector

* VDD: Voltage Drain Drain

Positive Voltage Supplies

* VEE: Voltage Emitter Emitter

* VSS: Voltage Source Source

Read more about the history of these names [here].

ADC

short for Analog to Digital Converter

op-amp

op-amp is short for operational amplifier
it can also be used as a buffer
if you connect the negative out back to the post gain out it can be negative feedback
using this buffer, we can add resistance to the feedback loop to control the total voltage added