working with electronics 20101007 - Sinica

Working with Electronics

Jyhpyng Wang

汪治平

中央研究院原子與分子科學研究所

Part 1: Circuit Construction

Circuit elements Tools Circuit diagrams Soldering and assembling Shielding and grounding Switch protection

Wires, heat-shrink tubes Resistors, capacitors, inductors, transformers Switches, relays Diodes and transistors Integrated circuits and sockets Varistors, fuses Light-emitting diode, neon lamps, meters Heat sink, mica sheet

Circuit Elements

American Wire Gauge (AWG)

number 18 20 22 24 26 28 30 32

diameter (mm)

1.02 0.81 0.65 0.51 0.40 0.32 0.25 0.20

resistance ohm/km

21 33 53 84 134 213 338 538

Color-Code of Resistors

Low-Power Resistor High-Power Resistor

Large resistors are often made of long coil of conductors. Watch out the parasitic inductance!

10-Turn Variable Resistor

3/4-Turn Variable Resistor

Electrolytic (1μF-10mF, for low-frequency circuits, polar, leaking, temperature sensitive, should be used with ceramic capacitors in parallel)

Tantalum (1μF-500μF, low-leakage electrolytic)

Polyester (Mylar) (1nF-10μF, general purpose, temperature sensitive)

Ceramic (10pF-0.1μF, high-frequency filtering, temperature sensitive)

Polystyrene, polypropylene (10pF-10μF, high quality)

Types of Capacitors

Electrolytic Capacitor Tantalum Capacitor

Polyester Capacitor

Polypropylene Capacitor

Ceramic Capacitor

InductorTransformer

Rotary Switch Relay

TransistorDiode

Integrated Circuit

Tools

Wire striper Soldering iron and solder Desoldering tool Multimeter Oscilloscope Drilling machine Punching machine

Soldering IronWire Striper

Desoldering tool

Multimeter

Oscilloscope

Screw drive with neon lamp

Neutral

HotGround

Hot

Neutral

Electric Outlets

Circuit diagrams

Symbols

Simulation and layout software

Circuit-board fabrication

resistor

capacitor

inductor

switch

ground

transistor

diode

voltage source

current source

transformer

operational amplifier

variable resistor

variable resistor

fuse

field-effect transistor

Zenerdiode

inverting amplifier

NAND gate

NOR gate

AND gate

OR gate

variable capacitor

AC power

lamp

quartz crystal

light emitting diode

Electronic Design Automation

Simulation:http://www.linear.com/designtools/software/index.jsp

Soldering

Solderable materials: Au, Ag, Cu, Sn Scraping off oxides Function of resin Bad contact Presoldering Desoldering

presoldering to ensure quality

bad contact

good contact

Soldering iron should touch both surfaces.

Assembling

Test boards Posts and angle brackets Test points Heat glue Wire stand Power line cramp Shielding Switch protection

Power Switches

PostTest Board

Angle Bracket

Wire StandBuzzer

Fuse Fuse Socket

Light-Emitting Diode Neon Lamp

Meter Battery Holder

Heat Sink Heat Conducting Paste

RG58 Coaxial CableRG174 Coaxial Cable

Power Line Cramp

Cable Tie

Heat Shrink Tube

SMA Connector

RCA Socket RCA Plug

F Connector BNC Connector

Electric-Field Shielding

Use coaxial cables (RG58, RG174)

Use shielded connectors (BNC, LEMO, RCA)

Use grounded metal case

Shielding and Grounding

transformer

3000 VAC

circuit

case

110 VAC

Ground Contamination

earth surface

underground water

hot neutral

ground

equipmentequipment

Lab A Lab B

leak

Supply and Grounding Order

Put high-power units closer to the power supply.

preamplifier

anti-coupling circuit

power amplifier

power supply

Magnetic-Field Shielding

Use twisted-pair wires to eliminate induction currents

Use cases made of high-μ metal

Avoid ground loop, use single-point grounding

Function of Twisted-Pair Wires

alternating magnetic field

induced current

alternating magnetic field

induced currents cancel

Switch Protectionspark

inductive load

100Ω

0.05μF

varistor

solutions

Part 2: Basic Electronics

Diodes and transistors Impedance and passive filters Amplifiers Active filters and oscillators Negative-feedback control Digital circuits Digital/analog interface

Semiconductors

P-type Si, Ge doped with B, Al, Ga, In

N-type Si, Ge doped with P, As, Sb

Current formed by moving holes

Current formed by moving electrons

Working Principle of Diodes

forward biasing

P N

holes electrons

conducting

reverse biasing

P N

holes electrons

non-conducting

Working Principle of Transistors

P N

B (base)

C (collector)E (emitter)

B (base)

C (collector)E (emitter)

N

electrons

Common-Emitter Amplifier

Vo

Vi

Vcc

RL

Rin

Ib

Ic

small signal gain =

Impedance of AC Circuit

capacitance

inductance

definition

Passive Filters

high-pass

low-pass

band-pass

Vi Vo

Vi Vo

Vi Vo

if

if

resonance:

Differentiators and Integrators

high-pass

low-pass

Vi Vo

Vi Vo if

if

equivalent circuit of coaxial cables

Impedance of Coaxial Cables

Assuming the impedance of an infinite-long coaxial cable is Z, and the inductance and capacitance per unit length is L and C respectively, then the impedance of a cable of lengthε(→0) in series with an infinite-long cable is still Z.

independent of

wrong method

correct methods

How to Connect Coaxial Cables

R

1MΩ load

signalsource

signalsource

1MΩ load

receiving end

T-connector

cable impedance, 50Ω for RG58 and RG174

receiving end

receiving end

receiving end

1MΩ load

signalsource

50Ω load

receiving end receiving

end

Input and Output Impedancevoltage source

current source

Zin

Zin

Zout

Zout

Impedance Matching

Zin = Zout

Zout

transmitting power =

Maximum transmitting power occurs at

Zin

Parasitic Capacitance and High-Frequency Response

Rout

Cp

Rout the smaller the better parasitic capacitance

VoVi

Compensation of High-Frequency Response

Rout

Cp

Rin

Cs

compensating condition:

compensating capacitor

parasitic capacitor

Rout Cs

Cp

Rin

input

output

DC Block and Low-Frequency Response

CbRin

Rin the larger the better

VoVi

Operational Amplifiers and Negative Feedback Control

V1

Vo

V2

+Vcc

-Vcc

V1

Vo

R1R2

V2

Active FiltersV1

Vo

CR

Low-frequency boost

if

V1

CR

Vo ifHigh-frequency boost

Frequency Response of Passive and Active Filters

Low-frequency boostHigh-frequency boost

High pass Low pass

f

f

f

f

Power Supply Rectifiers

without capacitor

with capacitor

120-Hz ripple

Regulated Power Supply

unregulated power supply regulated output =

Vz

without regulated circuit

Vout

with regulated circuitVout

Vz

Bistable Circuit

10kΩ

10kΩ

V+

V-

V+ or V-

Relaxation Oscillators

CR

10kΩ

10kΩ

Output switches when the capacitor is charged to V+/2 or discharged to V-/2

Vs

-Vs

Vs

-Vs

Vs /2

- Vs /2

Wien-Bridge Oscillators

CR

500Ω

C

R

Rl < 250Ω (1869 lamp)

ω = RC1

V1 Vo

V2

=Vo

V1

Vo

V2

= 3

low-distortion sinusoidal wave generation

is real and positive

with resistor with lamp

Basic TTL Digital-Circuit Blocks

+5V+5V

A

B

B = ~A

A

B

C

C= ~(A∩B) = (~A)∪(~B)

high (1): open circuit low (0): current flow in

inverter NAND gate

A∪B = ~[(~A)∩(~B)]

=

Decoder or DemultiplexerA A B B C C D D

0

1

9

demultiplexerinput

Encoder0 1 2 3 4 5 6 7

A

B

C

8 9

D

Multiplexerstrobe/enable A A B B

input 0

input 1

input 2

input 3

Bounceless Switch

Q

Q

Q

Q

1

1

1

01

00

1

1

01

0

Q

Q

1

0

0

10

1Q

Q

1

1

0

10

1

Latch (Register)

Q

Q

S

R

clock

Sn Rn Qn+1

Qn0 0

11 0

00 1

stay

set

reset

memorywrite-in

1 1 ?

Latch (Register)

Q

Q

S

R

clock

Sn Rn Qn+1

Qn0 0

11 0

00 1

stay

set

reset

memorywrite-in

1 1

0

1

0

1

1

1

01

0

?

Latch (Register)

Q

Q

S

R

clock

Sn Rn Qn+1

Qn0 0

11 0

00 1

stay

set

reset

memorywrite-in

1 1

0

0

0

1

1

1

01

0

?

Latch (Register)

Q

Q

S

R

clock

Sn Rn Qn+1

Qn0 0

11 0

00 1

stay

set

reset

memorywrite-in

1 1

0

1

0

1

1

1

01

0

?

Latch (Register)

Q

Q

S

R

clock

Sn Rn Qn+1

Qn0 0

11 0

00 1

stay

set

reset

memorywrite-in

1 1

1

0

0

1

1

1

01

0

?

Latch (Register)

Q

Q

S

R

clock

Sn Rn Qn+1

Qn0 0

11 0

00 1

stay

set

reset

memorywrite-in

1 1

0

1

0

1

1

1

11

1

?

Latch (Register)

Q

Q

S

R

clock

Sn Rn Qn+1

Qn0 0

11 0

00 1

stay

set

reset

memorywrite-in

1 1

1

1

1

1

1

?

0

1 0

1 0

0 1

0 1

Faster gate wins.

J-K Master-Slave FLIP-FLOP

Jn Kn Qn+1

Qn0 0

11 0

00 1

stay

set

reset

Qn1 1toggle

QJ

K

clock

preset

clear

Q

Q

master slaveCk

Pr

Cr

Q

Output changes state at clock’s falling edge.

Presetting a J-K FLIP-FLOP

QJ

K

clock

preset

clear

Q

Q

master slaveCk

Pr

Cr

Q

0

1

1

1

0

1

0

0

Presetting is done at clock’s rising edge.

Clearing a J-K FLIP-FLOP

QJ

K

clock

preset

clear

Q

Q

master slaveCk

Pr

Cr

Q

0

1

1

1

0

1

0

0

Clearing is done at clock’s rising edge.

Toggling a J-K FLIP-FLOP

Jn Kn Qn+1

Qn0 0

11 0

00 1

stay

set

reset

Qn1 1toggle

QJ

K

clock

preset

clear

Q

Q

master slaveCk

Pr

Cr

Q

1

1

1

0

0

1

1

0

0

1

this cyclenext cycle

Decade Counter

Q

Q

J

K

pulse

Cr

Q

Q

J

K Cr

Q0

Q

Q

J

K Cr

Q1

Q

Q

J

K Cr

Q2 Q3

Ck Ck Ck Ck

If any bit that goes into the NAND gate is reset, theCr disappears. Therefore Cr may be too short to clear all flip-flops.

unreliable clear!

Q

Q

J

K

pulse

Cr

Q

Q

J

K Cr

Q0

Q

Q

J

K Cr

Q1

Q

Q

J

K Cr

Q2 Q3

Ck Ck Ck Ck

Transition begins.

10 (earlier)1

1

01

10

10

10 10

Decade Counter

Decade Counter

Q

Q

J

K

pulse

Cr

Q

Q

J

K Cr

Q0

Q

Q

J

K Cr

Q1

Q

Q

J

K Cr

Q2 Q3

Ck Ck Ck Ck

Resetting.

10011

101

01 01

1(later)0

Decade Counter

Q

Q

J

K

pulse

Cr

Q

Q

J

K Cr

Q0

Q

Q

J

K Cr

Q1

Q

Q

J

K Cr

Q2 Q3

Ck Ck Ck Ck

A new cycle begins.

01 10

10 01

01

00

1

10

Decade Counter

Q

Q

J

K

pulse

Cr

Q

Q

J

K Cr

Q0

Q

Q

J

K Cr

Q1

Q

Q

J

K Cr

Q2 Q3

Ck Ck Ck Ck

Cr is latched.

10 0

0

1

1

1

1

Down Counter

Q

Q

J

K

pulse

Cr

Q

Q

J

K Cr

Q0

Q

Q

J

K Cr

Q1

Q

Q

J

K Cr

Q2 Q3

Ck Ck Ck Ck

Up/down Counter

pulseQ

Q

J

K Cr

Q0

Ck

Q

Q

J

K Cr

Q1

Ck

Q

Q

J

K Cr

Q2

Ck

Q

Q

J

K Cr

Q3

Ck

up/down

One-Bit Computer

input B

Instruction set: 0=add, 1=multiply

input A

instruction I

A*B (I=1)

A+B (I=0)

Series-In, Parallel Out

Q

Q

J

K Cr

Q

Q

J

K Cr

Q3

Q

Q

J

K Cr

Q2

Q

Q

J

K Cr

Q1 Q0

Ck Ck Ck Ck

clear

clock

series input

parallel output

Parallel-In, Series Out

Q

Q

J

K Cr

Q

Q

J

K Cr

Q

Q

J

K Cr

Q

Q

J

K Cr

Ck Ck Ck Ck

clock

series outputPr Pr Pr Pr

parallel input

Q3 Q2 Q1 Q0

R-2R Ladder D/A Converter

Vref

output

R R R

R

2R

2R2R2R2R

Servo A/D Converter

input

up/down counter

Q0

Q1

Q2

Q3

D/A converterclock

up/down

Digital-Analog Interface

analog to digital: Schmitt trigger + one-shot

digital to analog: pull-up resistor + buffer amplifier+5V

A

B

C

+5Vpull-up resistor (1-2 kΩ)

low-impedanceload

Schmitt Trigger

Vo

10k

Vi

+5V

10k

2.5V

input output

Schmitt Trigger with Hysteresis

Vo

10k

Vi

+5V

100k10k

2.5V

input output

Single-Shot Circuit

Vo

Vi R1R1

R

C

T = 0.69RC

T

0.7 V

-Vs

Vs

-Vs

2

Delay-Gate Generator

Vo

Vi

R1 C1

T1=0.69R1C1

Schmitt Trigger single-shot

R2 C2

single-shot

T1

trigger edge

trigger edge

T2=0.69R2C2trigger edge

T1

T1

trigger edge

T2

Part 3: Beyond Basics

Differential amplifiers Field-effect transistors Bootstrapping Power amplifiers Quartz oscillators Voltage controlled oscillators Phase detectors Phase-locked loops Frequency synthesis

Emitter Follower

Vo

Vi

Vcc

IB

RE

Biased Emitter Follower

Vo

Vi

Vcc

Ii

RE

R1

Vcc

R2

IB

Bootstrapping

Vo

Vi

Vcc

Ii

RE

R1

Vcc

R2

IB

R3

Push-Pull Power Amplifier

Vo

Vcc

R1

Vcc

R1

-Vcc

-Vcc

basic idea

Vi

Push-Pull Power Amplifier

Vo

Vi

Vcc

R

Vcc

-Vcc

The resistors reduce distortion and provide thermal stability.

Push-Pull Power Amplifier

Vo

VccR

Vcc

-Vcc

with bootstrapping

Vi

R

How to Become a Master

Try to repair broken electronics for others

Design and construct electronics for yourself

Read electronics catalogs and magazines

Read circuit diagrams of lab equipment

Visit the Guang-Hua Mall from time to time