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[http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+12.050203812241895+54+5+43%0Ag+-240+96+-240+112+0%0Ax+-134+-188+297+-185+4+18+Self-Oscillating%5CsComparator%5Cs(Square%5CsWave%5CsGenerator)%0Aa+-240+0+-128+0+8+15+-15+1000000+6.090293760309295+7.500070481327725+100000%0Aw+-128+0+-96+0+0%0Ag+-304+-16+-304+0+0%0A207+-96+0+-48+0+4+output%0Ac+-304+-16+-240+-16+0+1.0000000000000001e-7+-6.090293760309295%0Ar+-240+48+-240+96+0+100000%0Ar+-240+48+-128+48+0+100000%0Aw+-240+16+-240+48+2%0Aw+-128+0+-128+48+0%0Ar+-240+-64+-128+-64+0+100000%0Aw+-128+-64+-128+0+0%0Aw+-240+-64+-240+-16+2%0Ao+9+64+0+4098+10+0.00009765625+0+2+9+3%0Ao+13+64+0+4098+10+0.00078125+1+2+13+3%0A Square Wave Generator]
 
[http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+12.050203812241895+54+5+43%0Ag+-240+96+-240+112+0%0Ax+-134+-188+297+-185+4+18+Self-Oscillating%5CsComparator%5Cs(Square%5CsWave%5CsGenerator)%0Aa+-240+0+-128+0+8+15+-15+1000000+6.090293760309295+7.500070481327725+100000%0Aw+-128+0+-96+0+0%0Ag+-304+-16+-304+0+0%0A207+-96+0+-48+0+4+output%0Ac+-304+-16+-240+-16+0+1.0000000000000001e-7+-6.090293760309295%0Ar+-240+48+-240+96+0+100000%0Ar+-240+48+-128+48+0+100000%0Aw+-240+16+-240+48+2%0Aw+-128+0+-128+48+0%0Ar+-240+-64+-128+-64+0+100000%0Aw+-128+-64+-128+0+0%0Aw+-240+-64+-240+-16+2%0Ao+9+64+0+4098+10+0.00009765625+0+2+9+3%0Ao+13+64+0+4098+10+0.00078125+1+2+13+3%0A Square Wave Generator]
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* To shape the spectrum of our oscillators we will use a lowpass filter. The simplest form of a lowpass filter is the passive lowpass filter
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[http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+12.050203812241895+54+5+43%0Ag+-192+-64+-192+-48+0%0Ax+-196+-216+-12+-213+4+18+Passive%5CsLowpass%5CsFilter%0Aw+-192+-128+-160+-128+0%0A207+-160+-128+-112+-128+4+output%0Ac+-192+-128+-192+-64+0+1.0000000000000001e-7+0.6852026285128602%0Ar+-192+-128+-288+-128+0+1000%0AR+-288+-128+-336+-128+0+1+1591.5+1+0+0+0.5%0Ax+-13+-92+91+-89+4+14+f%5Cs%5Cq%5Cs1%5Cs/%5Cs(2*pi*R*C)%0Ax+-14+-67+180+-64+4+14+f%5Cs%5Cq%5Cs1%5Cs/%5Cs(2*pi*10%5E3%5CsOhm*10%5E-7%5CsF)%0Ax+-14+-40+156+-37+4+14+f%5Cs%5Cq%5Cs10%5E4%5Cs/%5Cs(2*pi)%5Cq10000/%5Cs2pi%0Ax+-14+-12+69+-9+4+14+f%5Cs%5Cq%5Cs1591,5%5CsHz%0Ax+-13+-130+293+-127+4+14+Calculation%5Csof%5Csfilter%5Cscutoff%5Cspoint%5Cs(-3dB%5CsFrequency)%0Ao+3+4+0+4106+1.25+0.00009765625+0+2+3+3%0A Passive Lowpass Filter]
  
 
[http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+9.001713130052181+54+5+43%0Ax+-132+-156+68+-153+4+18+Triangle%5Cs/%5CsSaw%5CsGenerator%0Aa+-240+0+-128+0+8+15+-15+1000000+0+3.6818713027031436+100000%0Ag+16+32+16+64+0%0A207+128+16+176+16+4+output%0Ac+16+-64+128+-64+0+1e-8+0.5101696765160468%0Ar+-240+48+-240+128+0+100000%0Ar+-240+48+-128+48+0+270000%0Aw+-240+16+-240+48+2%0Aw+-128+0+-128+48+0%0Ar+-64+0+16+0+0+100000%0Ad+-80+-64+-128+-64+2+default%0Aa+16+16+128+16+8+15+-15+1000000+0.000005101645748702981+0+100000%0Aw+16+-64+16+0+0%0Aw+128+-64+128+16+0%0Aw+128+16+128+128+0%0Aw+128+128+-240+128+0%0Ag+-240+-16+-288+-16+0%0Ag+-64+64+-64+80+0%0Ar+-64+0+-64+64+0+50000%0Ar+-128+0+-64+0+0+50000%0Aw+-128+-64+-128+0+0%0Ar+-80+-64+-32+-64+0+1000%0As+-32+-64+16+-64+0+1+false%0Ax+-21+-87+5+-84+4+8+triangle%0Ax+-16+-44+-3+-41+4+8+saw%0Ao+7+8+0+4098+20+0.00009765625+0+2+7+3%0Ao+8+8+0+4106+20+0.1+1+2+8+3%0Ao+3+8+0+4106+20+0.1+2+2+3+3%0A Trianlge / Saw Generator]
 
[http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+9.001713130052181+54+5+43%0Ax+-132+-156+68+-153+4+18+Triangle%5Cs/%5CsSaw%5CsGenerator%0Aa+-240+0+-128+0+8+15+-15+1000000+0+3.6818713027031436+100000%0Ag+16+32+16+64+0%0A207+128+16+176+16+4+output%0Ac+16+-64+128+-64+0+1e-8+0.5101696765160468%0Ar+-240+48+-240+128+0+100000%0Ar+-240+48+-128+48+0+270000%0Aw+-240+16+-240+48+2%0Aw+-128+0+-128+48+0%0Ar+-64+0+16+0+0+100000%0Ad+-80+-64+-128+-64+2+default%0Aa+16+16+128+16+8+15+-15+1000000+0.000005101645748702981+0+100000%0Aw+16+-64+16+0+0%0Aw+128+-64+128+16+0%0Aw+128+16+128+128+0%0Aw+128+128+-240+128+0%0Ag+-240+-16+-288+-16+0%0Ag+-64+64+-64+80+0%0Ar+-64+0+-64+64+0+50000%0Ar+-128+0+-64+0+0+50000%0Aw+-128+-64+-128+0+0%0Ar+-80+-64+-32+-64+0+1000%0As+-32+-64+16+-64+0+1+false%0Ax+-21+-87+5+-84+4+8+triangle%0Ax+-16+-44+-3+-41+4+8+saw%0Ao+7+8+0+4098+20+0.00009765625+0+2+7+3%0Ao+8+8+0+4106+20+0.1+1+2+8+3%0Ao+3+8+0+4106+20+0.1+2+2+3+3%0A Trianlge / Saw Generator]

Revision as of 22:26, 10 November 2019

Here you find learning material in the form of circuit simulations, that lead you to the understanding of amplifiers and other signal conditioning circuits that we use throughout the course. Feel free to experiment with them, they are editable and saved via the encoded URLuniform resource locator – a human readable web address which is looked up by the →DNS and translated into an →IP Address. You cannot destroy them and it is easy to share edited versions. Here is an introduction to the circuit simulator.

  • The foundation of understanding electric circuits is Ohm's law.

Ohm's Law

  • We can calculate series and parallel resistances with Ohm's law:

series and parallel resistances

  • A very powerful concept is the voltage divider, it allows us to attenuate (but not amplify!) any voltage in any circuit

voltage divider with even resistors

  • We will use the OpAmp (=operational amplifier) to amplify the small signals from our microphones to usable and less noisy signals before we digitize them in the computer. The opamp (= operational amplifier) is a three port device and its circuit diagram is a triangle. It has a positive and a negative input terminal and an output terminal. The most basic opamp circuit is the "comparator".

opamp as a comparator

  • the opamp's output can also directly follow one of its input voltages, but providing more current. This is the basis building block of opamp based amplifiers and is called "voltage follower" or "buffer".

stabilized opamp as a source follower

  • once you provide a voltage divider circuit in the feedback loop of an voltage follower, you are able to control the gain of the output port. This means the voltage of the output can be a scaled version of the input, either attenuating or amplifying the input voltage. Depending on whether the voltage divider is applied on the positive or negative input, the output is an inverted or non-inverted version of the input voltage. The two basic building blocks are shown below.

Inverting Opamp

Non-Inverting Opamp

Square Wave Generator

  • To shape the spectrum of our oscillators we will use a lowpass filter. The simplest form of a lowpass filter is the passive lowpass filter

Passive Lowpass Filter

Trianlge / Saw Generator

Trianlge / Saw Generator Lin Freq CV

Trianlge / Saw Generator Exp Freq CV


Saw Exp Feq CV

LFO Lin Freq CV

Saw+LFO+Filter

Two Sawtooth Oscillators with Detune and Mix

Oscillators, Filter and Gate