©F.M. Rietti Components Fundamentals

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 2 Components (cont) Passive –Resistors –Inductors –Capacitors –Transformers Active –Thermionics tubes –Semiconductors

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 3 Active Components Semiconductors –Are components build in a material that conduct current in one way, but is isolant in opposite way. –Can be realized natural material –Compound based upon chemical four valent elements Silicon Germanium –Doping these materials semiconductors are build

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 4 Active Components (cont) Diode –The most common function of a diode is to allow an electric current to pass in one direction (called the diode's forwarddirection), while blocking current in the opposite direction (the reverse direction). Thus, the diode can be viewed as an electronic version of a check valve. This unidirectional behavior is called rectification.check valverectification

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 5 Active Components (cont) Diode (cont) –At right side symbol for electrical schemas and how find cathode –Current run from anode to cathode, with a very low resistance –Resistance from cathode to anode is high, but not infinite

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 6 Active Components (cont) Diode Current Voltage Diagram Some diode are designed to resist at hi inverse currents (Zener diode) and used as Voltage stabilizer

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 7 Active Components (cont) Diode usage: rectifiers –Below an half wave rectifier, when voltage is in positive half wave period, diode is as valve open and current run, during negative phase current & voltage are is 0

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 8 Active Components (cont) Diode usage: rectifiers (cont) –Below an full wave rectifier using 4 diodes (Gratz bridge)

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 9 Active Components (cont) Diode usage: rectifiers (cont) –Below an full wave rectifier using 4 diodes (Graetz bridge)

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 10 Active Components (cont) Diode usage: rectifiers Zener Condenser stabilized (cont) –Below an full wave rectifier using 4 diodes (Graetz bridge) a condenser to fit periods with sinusoid below a V dependant from RC time constant and Zener diode to fix Vout to a constant value. –This is most common power supply schema for fixed output Voltage

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 11 Active Components (cont) Transistor –It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals. semiconductorcurrent –Terminal are named: C(ollector) B(ase) E(mitter)

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 12 Active Components (cont) Transistor (cont) –Physics of transistor was good explained at s link: How Transistor Work –Looking at schema at right side, there is a simple circuit with a transistor ; when a 0.7V, or above, applied from base and emitter (common) transistor became as short cut and a current run from battery to Led 1 and Resistor 1. Transistor is as a breaker piloted by a tension

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 13 Active Components (cont) Transistor (cont) –Common emitter amplifier Circuit explanation at: –Emitter Common AmpEmitter Common Amp Above link explain how transistor currents are related Result is that: –V out (t) = A * V in (t) –A>1

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 14 Active Components (cont) Transistor (cont) –Logic gates Logic AND –If V A and V B are > than V for transistor conduction both transistor are short cuts and +6V arrive to 4.7K resistance; a Volt meter in out measure 6V –If V A or V B are below no out

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 15 Active Components (cont) Transistor (cont) –Logic gates Logic OR –If V A or V B are > than V for transistor conduction one of two or both transistor are short cuts and +6V arrive to 4.7K resistance; a Volt meter in out measure 6V –If V A and V B are below no out

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 16 Active Components (cont) Transistor (cont) –Logic gates Logic NOT (or inverting buffer) –If V A is > than V for transistor conduction transistor is short cut and Out is connected to ground; a Volt meter in out measure 0V –If V A is transistor is as an open junction and from Out to ground 6C can be measured

©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 17 Active Components (cont) Transistor (cont) –Operational amplifier V out =A0(V n.inv – V inv ) –Commonly used as comparator