Basis of Electrical Circuits

Basis of electrical circuits.1important electrical parameters and type of currents.AB2electronic components and circuits.1FE=Q[%]electric field strengthu=w[v]ValiageEkin = U.Q [I]P= = U.I [w]+powerR=4/1u[n]11 ohm's laws)Resistanceto resistorC=Q[F]+ucapacitanceof capacitorI=DQ[A]WILL typesDirect currentelectrons flow like watercurrent interestyst(D.C)in a plastic in tube (hose)electricity flows directlythrough the entire circuit.frequency is zero.Alternative currentelectrons move back and forth.(A.C)it does have a frequency.(repeating motion) 2Aelectronic components andBTheir circuits1- resis tor (R)A resistor is a passive electrical component with primaryR.function to limit the flow of electric current.in dependent of frequencyexamplelike flow of water in a hose.I+P1P2opouR111110The resistance of a resistor Con be described by the ohm's law.uoR=uarms:+=in (D.C)F2I4,rmsIeR= Urms in (A.C)ITIrmsRwe use resistors in like lamp circuitsu = U. - sin (wt)because the lamp it self doesn't have aresistance and it will burn with theapplied Voltage.Con ductor elemento can haveresistance:R=lR ~dayARNl R.R2in series. Rtotal = R1 + R2R.in parallel.R2=Voltage divider (D.C)R1The simplest basic electric circuit, whichconsists of two resistors connected inUinIseries. The ratio of the resistancestotaldetermines what fraction of the inputvoltage will appear on the outputR2Uoutelectrodes. According to ohm's lawIIR1=U4(0in)R2Uout=UC.R2=U2(aout)outinR1+R2*by changing the short circuit position we canI=="control the output voltage from tera to max.Rtoles in series - Rq+R2protentiometerR2Vout2. capacitor(c)stores electrical charge like a short life battery.11in series + CT C4 c2uses two metal plates separated by an insulatorin parallel +CT=C1+C2stores charges by taking the electrons from one sidean pumping it to the other side. (frequency dependent))Q= C uQC=uper voltcapacitance means How much charge you can hold per voltage (charge efficiency)ICT QTup QTit is constant and it only depends on the constructional of the capacite.independent of voltagecommitment -:C constant.atCn1TCNA RC circuit-elements in DC circuitsCharging (1) and discharging (2) a serial RC circuitSo called "transient" phenomena take place2From Kirchhoff's 2nd law: U = UR + Uc.1D.CRchargingprocess inU R = U e RC , UC = RC)UCcase of Rtime constant (s)and CU0.fully charged.UCUCU-exportingURdecrease.tchargingURtFrom Kirchhoffs 2nd law:discharging UR + Uc=0-UprocessUR= = -Uoe RC , Uc=UeRC/dischargingif we put a capacitor in the circuit:u D.CAfter switch on the voltage, the chargesCI-will be trapped on the capacitor ,then theRcurrent flow stops , because the potential difference ofcapacitor will be equal to the potential difference of the Source.So in D.C circuits after a certain amount of timethe current stops. But in case of A.C circuit the current will not stop,because the current can discharge and charge thecapacitor at each period.uA.CoICIchargingRI,I- I. sin (wt)tTdischargingin case of A.C, the capacitor has an impedancewhich means the resistance in A.C. .impedance of a capacitor (c)Xc 2MF 1 C = WC 1if the charging and dis charging process take a longer timemeans that capacitance and resistance are high (low current flow).also if it takes shorter time the R, C are low (high current flow).AC filter circuitsFilter circuits are practically voltage dividers, the only differenceis that one of the resistors is replaced by a capacitor. This smalldifference, however, essentially changes the properties of thevoltage divider, since the AC resistance (impedance) of thecapacitor depends on the frequency (f).12nfC High pass filterClog Un Uoutlog fdlog0UinRUouttransmitting characteristicsUout out = U in 1 + 2nfCR (2nfCR)2U...(2) =U in R2 R + XpgXcvAoutLow pass filterRlog USA UoutUinlog folog f0UinCUouttransmitting characteristics1= inUour(1)= = in R2 X S +X2XcUout 3- inductor (L)it is a electrical circuit component which storesenergy in it's magnetic field. (B)LC circuit (oscillating circuit)A circuit consisting of a capacitor and a coil is called an oscillatingcircuit, or LC circuit.If the capacitor of the LC circuit is charged to a certain voltage andleft undisturbed, the voltage on the capacitor will undergosinusoidal oscillation. Because of the ohmic resistance of the coil,the amplitude of this oscillation will decrease exponentially, i.e.the oscillation is damped.BBabCdefgh2U1UTTThe voltage on the capacitor of an ideal and a realistic oscillator isconstant amplitude and damped sinusoidal, respectively AnodecathodeSemiconductor electrical elementsIISemiconductor diodep-typen-type(+) charge carriers(-) charge carriersThe semiconductor diode consists+of an n-type and a p-typesemiconductor. It allows the1forward biaseddepletionelectric current to flow only in onezoneIfdirection.-+depletion KoneVR&forma when there is reversed bine (no free charges)VFhigher the voltage wider the depletion zonehas find space charges.IR2(Ireverse biased!!Transistors(no conduction) no currentThe first transistor was invented in 1949 (Nobel Prize in 1956).2 typesBio polar (BJT)current controlled device.Ic function ofIBField effectTwo main functions1. switch circuits on and off2. amplify signals.FETunipolar3 terminal device.=Voltage controlled deviceI Dfunction of UGS and "DsDrain ofDrainRIelectronsIDSchancel(resister)N"GSmore (-)gatePP+depletion zoneAsource or ofelections.RN1 FET (Field Effect Transistor)The controlling voltage sets thethickness of the empty layer, whichID tdrain (D)+can be seen in a diode. Changingnthe cross section area of aconductor can be used to regulatereducedgate (G)cross sectionthe current. The great advantage ofpthe FET is that, practically, there iscontrolledno current on the controllingcontrollingcurrentelectrode, SO the input power isvoltagen(SD)very low. This became a veryUGSsource (S)important respect as the integratedcircuits spread. The moretransistors are squeezed into anintegrated circuit, the less heat can be produced by one transistor.IDSVGso=0VVGS1=-0.5VGs2=-1VGs3=-1.5VDSa resistor!