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electricity_basics

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electricity_basics [2016/06/03 17:43] – [D-Transistor] psykhazeelectricity_basics [2016/06/03 17:55] (current) – psykhaze
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-====== Electricity Basics ====== + bla
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-{{:electricite.jpg?direct&400|}} +
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-In order to understand better electronics, some basics in electricity are needed. +
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-=====1 - Fundamentals===== +
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-In order to explain electricity, let's imagine a waterfall. A stream going from where there is something to where there is not. Electricity is the same, it's a stream of positive charges going from + to -. (Since the electrons themselves are negatively charged, they move from - to +; but the subtlety of this only matters in semiconductor design.) +
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-{{ :waterfallz.jpg?direct&300|}} +
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-But let's stay on the waterfall: +
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-- The electricity equivalent to the **Volume** of water dropping is called **Current** ( the quantity of electrons which are moving)  +
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-- The electricity equivalent to the **Height** of the waterfall is called **Voltage** ( the energy of each electron). +
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-If we want to calculate the power of our water stream we will have to take volume and height in consideration, which gives us: //Power = Volume x Height// +
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-//Let's transpose it to electricity, it gives us : Power = Voltage x Current , so in electric units ://  +
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-//**Watts = Volts x Amperes**// +
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-=====2 - Ohm's Law===== +
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-If we put some rocks in the water before it falls it will create the equivalent of an electrical phenomenon called **Resistance**. The move of water stream between our rocks gets accelerated , it gains in energy in the smaller spaces between rocks. It's like when the water gains energy by falling. +
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-{{ :neonking:cailloux-eau.jpg?direct&300 |}} +
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-Electrically We can deduce **Voltage = Resistance x Current** , so in electric units :  +
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-//**Volts = Ohms x Amperes**// +
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-This is called Ohm's Law. If we want to convert an unknown value between Voltage-Resistance-Intensity, you can rearrange the formula. +
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-//For example if we want to define an unknown resistance, we have : +
-Resistance = Voltage / Current// +
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-=====3 - Capacitance===== +
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-Capacitance is the ability of a body to **store** an electrical charge. A material with a large capacitance holds more electric charge at a given voltage, than one with low capacitance. +
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-{{ ::neonking:kerrdam.jpg?direct&200 |}} +
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-In comparison to water , capacitor is like a dam in the middle of our water flow, storing water for some time. +
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-The unit for electrical capacitance is **Farad**. +
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-=====4 - Base Audio Signals for Synthesis : Getting into the Sound===== +
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-====A-Sound and Signals==== +
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-Sound is compression waves of changing air pressure over time, produced by some physical object moving back and forth (e.g. a speaker head).  +
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-{{ ::neonking:sound_from_a_speaker.gif?direct |}} +
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-Since a speaker's position is proportional to its input voltage, **analog audio signals are usually represented as changing voltages over time.**  +
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-Sometimes they are changing currents through a node at constant voltage, but changing voltages are much more common (e.g. this is what is present on a Line Out jack from a synthesizer).  +
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-Audio equipment is typically calibrated so that a variation of +/- 1 volt from ground (0V) is a loud sound for line level inputs/outputs; outputs that drive speakers can sometimes reach 50 volts or more (for several hundred watts sound systems). +
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-====B-Base Wave Shapes==== +
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-Let's have a look to some base audio waveshapes and how they look when changed in amplitude and in frequency. +
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-{{ ::neonking:audiosignals-en.jpg?direct |}} +
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-That already gives us some good basics . Some more signals : +
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-{{ ::neonking:audiosignals_en.jpg?direct |}} +
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-====C-Wave Modulation==== +
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-When you use a signal to modulate an other you have the following: +
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-{{ ::neonking:am_fm.jpg?direct |}} +
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-====D-Audiovisual Example==== +
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-Finally, here are some demos on the oscilloscope: +
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-{{youtube>PQM8ozRQzI8?big}} +
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-//TODO : Center the vid (didn't managed to do it -_- ) and remake it with a SID or FM synth  for example// +
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-=====5 - Mixing and Filtering===== +
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-Let's see the principle +
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-**// Mixinig/Filtering Gfx on correction//** +
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-Basically by adding two different frequency signals it gives a signal more complicated and stronger, and by removing a portion of the signal frequencies we're getting something simpler but more accurate. An audio mixer provides complete these two functions simultaneously , for example. +
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-Audio filtering need some more precisions though : +
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-**// Filtering Gfx2 on correction//** +
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-=====6 - Analog / Digital, what's the difference?===== +
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-As described above, analog audio is usually a changing voltage over time.  +
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-Digital audio is an array of (numeric) samples, each one corresponding to a particular amplitude/voltage at a particular time.  +
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-Therefore, when converted to digital form, audio has to be quantized (digitized, or divided into discrete elements) in both amplitude (voltage) and time. Here is the quantization in time: +
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-{{ ::neonking:analogseq2digital-en.jpg?direct |}} +
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-The frequency of the sampling (the little dots) is called the **sample rate**; common values are 44.1 kHz and 48 kHz. The higher the value, the better the accuracy of the digital representation. +
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-The signal also has to be quantized in voltage/amplitude, because the computer has to represent each sample as a single number (with limited precision, often an integer (float for high precision) ). +
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-{{ ::neonking:effetescalier-en.jpg?direct |}} +
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-If the numbers representing samples are integers, the quality of the quantization is called the **bit depth**.  +
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-Examples include 16-bit and 24-bit audio; these mean that each sample is represented by : +
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--**16-bit integer** = 2^16 = **65,536 possible levels**  +
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--**24-bit integer** = 2^24 = **about 16 million levels** +
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-//(8 bits depth = 2^8 = 0 to 254 levels and if we get signed -127 to +127 )// +
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-Often these values are represented as floating-point numbers within the computer, which gets rid of almost all the error (especially in modern DAWs that use 64-bit floating point); but the conversion to or from analog has to be done using an integer, and true 24-bit accuracy is almost impossible to get - and extremely expensive -. Most "24-bit" converters are actually effectively about 20-21 bits, due to noise and other factors. +
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-=====7 - Resistor, Capacitor, Diode and Transistor===== +
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-//Back to Electricity !//  +
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-There are some basic components used in electronics that need to be covered before going further. +
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-====A-Resistor==== +
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-{{ ::neonking:resistors.jpg?direct&300 |}} +
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-The resistor is a unpolarized passive component with a resisting value in ohms that acts in voltage regulation in circuitry. +
-The color stripes on it describes it value, following a color code +
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-{{ ::neonking:resistor-color-code.jpg?direct&300 |}} +
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-===Symbols=== +
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-Here are the symbols for different types of resistors +
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-{{ ::neonking:resistors_symbols.png?direct |}} +
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-====B-Capacitor==== +
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-{{ ::neonking:capacitors_types.jpg?direct&300 |}} +
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-The capacitor is a passive component used to store electrical energy temporarily in an electric field with a value in farads . It is sometimes Polarized (Electrolytic), sometimes not (Ceramic) +
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-//TODO: Add a link to a Farad converter, remake symbols Gfx// +
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-===Symbols=== +
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-{{ :neonking:types_of_capacitor.jpg?direct&300 |}} +
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-====C-Diode==== +
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-{{ ::neonking:diodes.png?direct&300 |}} +
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-A diode is a polarized passive component that let pass the electrical flow in only one way +
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-===Symbols=== +
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-//TODO: Remake this Gfx// +
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-{{ ::neonking:diode-symbols.gif?direct |}} +
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-====D-Transistor==== +
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-{{ ::neonking:transistor-packages.jpg?direct&300 |}} +
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-The Transistor is an **active** component that works as an **amplifier** or a **driven switch**. +
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-**BJT**s and **FET**s perform **similar** functions, but with a **different type of input**.  +
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-Both kinds of transistors are devices that control the current flowing through them and can be used as digital switches or analog amplifiers.  +
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-In the digital case, the circuit around the transistor is designed so the input signal (current for a BJT or voltage for a FET) is large enough to turn on the transistor much more than the actual needed output current, or small enough to turn off the transistor completely.  +
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-In the analog case, the circuit is designed so that the transistor is operated in the region where small changes in input signal cause large changes in output current. +
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-===Symbols=== +
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-Following the technology the transistor has been built, it has several symbols +
-The current being controlled (i.e. the output current) is from top to bottom in all these pictures, i.e.: +
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-**// Gfx on correction //** +
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-from emitter to collector for PNP +
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-from collector to emitter for NPN +
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-from source to drain for P-channel FET +
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-from drain to source for N-channel FET +
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-The third pin, base or gate, controls the amount of current flow between the other two pins. The difference between a BJT and a FET is that in a BJT, the output current is a function of the CURRENT between base and emitter, and in a FET the output current is a function of the VOLTAGE between gate and source. +
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-=====8 - Kirchhoff's Circuit Laws===== +
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-In electricity , as with water , the flows tend to regulate .  +
-The following relationships helps a lot about solving values in circuitry : +
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-//TODO: Remake Gfxs// +
-====A-Current Law (KCL)==== +
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-{{ ::neonking:kirchhoff_circuit_laws.png?direct |}} +
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-In other words , in a node , Current going to the node equals Current going from the node +
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-//**i4** = i3 + i2 - i1// +
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-====B-Voltage Law (KVL)==== +
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-{{ ::neonking:kirchhoff_voltage_law.png?direct |}} +
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-In other words, the voltage is balanced along the components rings ; **ad** = ab + bc + cd +
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-//**V4** = V3+V2+V1// +
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-=====9 - Serial and Parallel Circuits===== +
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-**Current** is the same for all of elements in a **Serial** circuit  so :// **Total Current = Each component Current**// +
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-**Voltage** is the same for all of elements in a **Parallel** circuit so : // **Total Voltage = Each component Voltage**// +
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-//TODO: update gfx and represent Rtotal and Ctotal// +
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-====A-Resistors Serial mounted==== +
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-{{ ::neonking:resistors_in_series.png?direct |}} +
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-**RTotal** = R1 + R2 + ... + Rn +
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-====B-Capacitors Serial mounted==== +
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-{{ ::neonking:capacitors_in_series.png?direct |}} +
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-**(1/CTotal)** = (1/C1)+(1/C2)+... +(1/Cn) +
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-====C-Resistors Parallel mounted==== +
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-{{ ::neonking:resistors_in_parallel.png?direct |}} +
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-**(1/RTotal)** = (1/R1)+(1/R2)+... +(1/Rn) +
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-====D-Capacitors Parallel mounted==== +
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-{{ ::neonking:capacitors_in_parallel.png?direct |}} +
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-**CTotal** = C1 + C2 + ... + Cn +
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-=====10 - Operational Amplifier===== +
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-//TODO : Redraw Gfx // +
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-An operational amplifier (aka OpAmp) is an electronic Integrated Circuit (IC) used in many purposes like amplifiers, mixers, filters and oscillators +
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-====A-Symbol==== +
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-{{ ::neonking:op-amp_symbol.png?direct |}} +
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-Vcc is the "power supply" voltage for the Operational amplifier +
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-====B-Non inverted Amplifier==== +
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-{{ :neonking:aopnoninverting.svg.png?direct |}} +
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-**Ve** = Vs x ( R1 / ( R1+R2 ) ) +
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-**Vs** = Ve x ( 1 + (R2/R1) ) +
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-// TODO : add gain formula  + example in + out signals from this circuit // +
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-====C-Schmitt Trigger aka self triggered comparator==== +
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-{{ ::neonking:aopschmitt.png?direct |}} +
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-{{ ::neonking:hysteresis_sharp_curve.png?direct |}} +
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-**(+/-)VTrigger** = (+/-)Vcc x ( R1/R2 ) +
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-//TODO: Give some more explanations about how the trigger works //  +
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-====D-Basic Oscillator==== +
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-{{ ::neonking:oscillator.png?direct&300 |}} +
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-//TODO : Explain the derivative from schmitt trigger . Add some relations between voltages and components values and a demo input/output signals// +
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-====E-Basic Mixer==== +
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-{{ ::neonking:audio-mixer.jpg?direct&300 |}} +
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-====F-Basic Active Filters==== +
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-===Low-Pass Filter=== +
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-A low-pass filter let pass through frequencies below their cutoff frequencies, and progressively attenuates frequencies above the cutoff frequency. Low-pass filters can be used in audio crossovers to remove high-frequency content from signals being sent to a low-frequency subwoofer system. +
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-{{ ::neonking:active-lp.jpg?direct |}} +
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-===High-Pass Filter=== +
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-A high-pass filter does the opposite, passing high frequencies above the cutoff frequency, and progressively attenuating frequencies below the cutoff frequency. A high-pass filter can be used in an audio crossover to remove low-frequency content from a signal being sent to a tweeter. +
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-{{ ::neonking:active-hp.jpg?direct |}} +
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-===Band-Pass Filter=== +
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-A bandpass filter passes frequencies between its two cutoff frequencies, while attenuating those outside the range. ( the contrary is a band-reject filter, wich  attenuates frequencies between its two cutoff frequencies, while passing those outside the 'reject' range). +
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-{{ ::neonking:active-bp.jpg?direct |}} +
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-//TODO : Add some -simple- relations between R & C / Cutoff Freq in the active filters circuits// +
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-=====11 - Going Further===== +
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-https://en.wikipedia.org/wiki/RLC_circuit +
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-https://en.wikipedia.org/wiki/Transistor +
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-https://en.wikipedia.org/wiki/Operational_amplifier +
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-https://en.wikipedia.org/wiki/Integrated_circuit +
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-https://en.wikipedia.org/wiki/Vacuum_tube +
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-https://en.wikipedia.org/wiki/Fast_Fourier_transform +
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electricity_basics.1464975816.txt.gz · Last modified: 2016/06/03 17:43 by psykhaze