Basic Electronics Review B Furman 25 AUG 2015

Basic Electronics Review B. Furman 25 AUG 2015

Lecture Flow Today n Items to focus on this week Lab 1 ¨ Port. Master build ¨ HW 1 and Questionnaire due Thursday ¨ Term Project overview + video of past projects ¨ n Basic electronics review: Voltage, current, resistance, capacitance, inductance ¨ Equivalent resistance ¨ Voltage divider ¨ Impedance of a capacitor ¨

Learning Objectives n n n Get prepared for Lab 1 and started on Port. Master build Get started on the term project Explain in simple terms what is meant by: ¨ ¨ ¨ n n n Voltage Current Ground Resistor, Capacitor, Inductor Impedance Power Determine equivalent series and parallel impedances Explain the significance of a voltage divider Derive an expression for the impedance of a capacitor

Mechatronics Concept Map Power Source User Interface ME 106 ME 120 Controller ME 106 (Hardware & Software) Power Interface INTEGRATION ME 106 ME 154 ME 157 ME 195 Signal Conditioning ME 106 ME 190 ME 187 ME 106 ME 120 Actuator Sensor System to Control ME 110 ME 182 ME 136 ME 189 ME 154 ME 195 ME 157 ME 120 ME 297 A BJ Furman 22 JAN 11

Lab 1 – Intro to the Mechatronics Lab Read and prepare n Take the pre-lab quiz before you start your lab session n

Port. Master Solder practice n Bit manipulation and port IO learning n

HW 1 and Questionnaire When are they due? n Hard and softcopy for Questionnaire n Soft copy only for HW questions n

Term Project Overview n See the guideline: http: //www. engr. sjsu. edu/bjfurman/courses/ME 1 06/ME 106 pdf/ME 106 termproject. doc n Video sample of previous projects

Key Concepts n n n n Voltage Ground Current Resistor Capacitor Inductor Impedance Power Ø Ø Ø Take out a sheet of paper Explain the concepts in terms that a 6 th grader could understand First, work on your own, then, introduce yourself to someone you have NOT met yet, and share your answers.

Basic Electronics Review - 1 n Voltage – put it in terms that a 6 th grader could understand ¨ “Pressure” n n n Pressure on electric charge (e-). Units are in Volts Urges charge to ‘flow’ Measured relative to a reference pressure level ¨ An “across” quantity – we measure it across two points (Don’t say ‘the voltage through…’) A “High” pressure B R 1 + R 2 Vi C “Low” pressure R 3 D Voltage source acts like a pump Ground is often taken as the low pressure point, but any point could be taken as ‘ground’ ex. VAD = Vi = -VDA

Basic Electronics Review - 2 n Current – put it in terms that a 6 th grader could understand ¨ “Flow” n n n Flow of electric charge (e-). Units are in Amps The response of charge to applied voltage Need a complete circuit for current to flow ¨ A “through” quantity – we measure it through an element A “High” pressure B R 1 + R 2 Vi I “Low” pressure C R 3 D We will assume ‘conventional’ current flow – positive charges flow out of the + terminal and return to the - terminal

Basic Electronics Review - 3 n Resistor – put it in terms that a 6 th grader could understand ¨ “Flow restriction” (causes a pressure (voltage) drop across it), an impedance n Drinking a milkshake through a straw ¨ ¨ Small diameter straw – high resistance § Causes large pressure drop Large diameter straw – low resistance § Causes small pressure drop Units are in Ohms ¨ Dissipates power in heat! ¨ A “High” pressure B R 1 + R 2 Vi C “Low” pressure R 3 D

Basic Electronics Review - 4 n Ohm’s Law (know it cold!) ¨ V=I*R n A relationship between current and voltage for a resistor ¨ ¨ The slope of the V-I line The voltage drop across a resistor is proportional to the current through it V I V, volts R R I, Amps R increasing

Basic Electronics Review - 5 Original Circuit n A Vi Equivalent Circuit A R 1 + + R 2 Vi D Req R 3 D

Basic Electronics Review - 6 n Power (units are in Watts) ¨P = I 2 R = (V/R)2 R = V 2/R ¨ P = I 2 R = I 2(V/I) = IV n Note: can calculate the power required for any circuit by measuring I and V and taking their product Any circuit A I B R 1 + R 2 Vi C R 3 D

Capacitor n Capacitor– put it in terms that a 6 th grader could understand ¨ “Accumulator”, water tank n n Pressure storage. Stores energy in an electric field Voltage across the leads takes time to build up. Units of capacitance are Farads V + -

Inductor n Inductor – put it in terms that a 6 th grader could understand ¨ “Flywheel, merry-go-round” n n An inertia. Stores energy in a magnetic field Tries to oppose changes in current flow. Units of inductance are Henrys V + i

The Voltage Divider Consider two resistances in series n What is VA in terms of n ¨ V i, R 1 and R 2 Vi + R 1 A VA R 2 D

So what? Why is this important? n Voltage divider effect occurs whenever one circuit is connected to another n Voltage dividers can be used to set a voltage level somewhere between a given supply voltage and ground ¨ If significant current is desired, it is better to use a power supply or voltage regulator