2020 design question - mit6.101 spring 2020 lecture 10 2 2020 design question •when landline...

• Sensors/Actuators• Opto‐isolators• Triacs• Final Project• CIM

6.101 Spring 2020 Lecture 10 1

Quiz 3/19/2020• Start time: 2:35PM to 3:55PM• Notes: one sheet handwritten – double sided

• Calculator allowed – no data retrieval• Quiz questions based on psets, lecture notes through Lecture 11, lab exercise 1‐5– Resonance– Diodes, BJT, MOSFET, JFET circuit– Op‐amps– 1 design problem

• Check your grades!


2020 Design Question

• When landline telephone rings and in use, room sound system volume decreases by 6db

• Ring signal: 20Hz 70vpp centered at zero• In use voltage: 10VDC• Input impedance 100K min• Response time <0.2 sec

6.101 Spring 2020 Lecture 10 3 6.101 Spring 2020 Lecture 10 4

Ring signal: 20Hz 70vppcentered at zero

In use voltage: 10VDCInput impedance 100K minResponse time <0.2 secLED 2V, 10ma6db attenuation


Heart Rate & Step Monitoring circa 2000

20002015

Sensors/Actuators

• MEMS• Gyros• Triacs• Opto‐isolators• Voice Coils• Electret Microphones• Servos• Motors


MEMS Accelerometers

• MEMS – MicroElectroMechanical Systems• MEMS components generally 1‐100 microns• Silicon based – MEMS device fabricated on same silicon as circuits

• Analog circuits key to MEMS


Movement sensing

• Accelerometers– Acceleration – movement from one point to another

– Tilt sensing – measures inclination/angle wrt to gravity

• Gyroscopes– Rotation sensing – measures angular rate.



Differential Capacitors*

6.101 Spring 2020 Lecture 10 10*6.777J OCW

Differential Capacitors


sVCCCCV

21

210

With movement a displacement current is generated.

ADI XL50 1 Axis Accelerometer


2 Axis Acceleromter


ADXL325 – 3 Axis Accelerometer

• 3-axis accelerometer now used in cell phones, games, iPods, laptops, 6.1xx projects

3 Axis 5G accelerometer

14Lecture 106.101 Spring 2020

Mems

• Passenger sensor• Tire pressure sensor• Airbag deployment• 6.101 Project

– Measure speed/strength– Macro size Mems– Labyrinth game– Step counter


Gyroscope

• Mems based• Applications

– Image stabilization (cameras)– Rollover sensor (auto‐airbags)– Robot arm control


6.101 Spring 2020 Lecture 1017

Credit: STMicroelectronics

Thrysistors ‐ Triacs

• Triac – Triode for Alternative Current• Applications: solid state relays, lights, motors, power systems.

• Operation– When gate current exceeds Igt, device conducts

– Four quadrants: • Q1: G+, MT2+• Q2: G‐, MT2+• Q3: G‐, MT2‐• Q4: G+, MT2‐


MT2

MT1

G

MAC97 Triac


Max Rating

$0.54

MAC97 Triac


Trigger

High Current Triacs

$1.80


Triac – Operating Environment

• Large dv/dt may cause triacs to turn on. • di/dt during turn on must be limited.• Limit with snubber network: RC


Optoisolators

• Electrically isolate circuits in two voltage domains

• Isolator achieved through vacuum or air gap

• Typical isolation: 5000 volts rms

6.101 Spring 2020 Lecture 10 23 6.101 Spring 2020 Lecture 10 24

$.37

$.90

$.71

LTV847 Max Ratings


LTV‐847


What is Common?


Voice Coil


services.eng.uts.edu.au/cempe/subjects_JGZ/ems/ems_ch11_ppt.pdf

Electret Microphones

• Condenser mic with permanent permanently charge diaphram

• Inexpensive ~$1• Reasonable frequency response• Built in JFET for amplification


*

*http://en.wikipedia.org/wiki/File:Electret_condenser_microphone_schematic.png


CMA-4544PF


Stepper Motors

• DC motors with permanent motors and multiple coils around the body.

• Coils are turned on and off in sequence to cause the motor to turn.

• Because the coils are turned on and off they are easy to control with microcomputer and digital circuits. At any given time, the position of the shaft is known.

• Holding torque requires power.


www.sparkfun.com/products/9238

$15


Servos

• Servos are motors with electronic circuitry that controls the angular position of the shaft based on a control signal. If the angle is incorrect the motor is turned on until the correct position is reach.

• Angular position controlled by a 0 – 2.0 ms pulse width.

www.sparkfun.com/products/10189

$12

20KPPS Galvonometer


Parts

• Free parts from Texas Instruments

• Free parts from and Analog Deviceshttps://form.analog.com/Form_Pages/corporate/parts.aspx


Final Project

•Schedule, Organization•Choosing a topic•Example projects•Grading•Design Suggestions•Writing workshop

6.101 Spring 2020 36Lecture 10

Final Project: Schedule• Choose project teams (email gim by Fri, Mar 20)

– Teams of two or three. A single person project requires approval of lecturer. Pizza: Wed evening in 36‐6 lobby

– Start project ideas/discussion with staff &Joe Sousa, Linear Engineer

• Project Abstract (due Thu Apr 2, submit on‐line)– Arrange meeting with staff– About 1 page long describing overall project

• Project Proposal Draft (due Thu Apr 9, submit on‐line)– A more detailed proposal with block diagram in preparation for block diagram

discussion with staf, clearly identifying who’s doing what– About 2‐3 pages; to be revised after block diagram conference

• Block Diagram Conference with mentor (by Fri, Apr 10)– Review major components and overall design approach– Specify the device component– s you need to acquire (small budget allocated for each project if component does

not exist in the stock room). Get approval from me


Schedule (cont’d.)

• Project Design Presentation to class – Tue Apr 14 @7p & Thu 16 2:30p– Each group will make a 10‐15 min electronic presentation

(~10 slides) dividing presentation among team members– Submit PDF on‐line, will be posted on website– Required attendance (2% grade)

• Project Checkoff Checklist to staff (Fri Apr 24)– Each group in discussion with mentor creates a checklist of

deliverables (i.e., what we can expect each team member to demonstrate). Submit PDF on‐line.

• Final Project Demo/Checkoff/Video (Tue/Wed May 5 & 6)– Video posted on‐line with your permission

• Final Project Report (Tu May 12 – 5p)– Submit PDF on‐line, will be posted on website– Sorry, no late reports will be accepted


Team Organization• Most importantly, you need one• Key decisions made jointly

– Requirements– High level design– Schedule– Who will work on what, who’ll take the lead– Response to slippage

• Lower level design exchanged for examination– Everyone responsible for everything– Design reviews tremendously helpful

• Try it, you’ll like it

• Communicate with each other early and often


Controlling Schedule

• First, you must have one• Need verifiable milestones• Some non‐verifiable milestones

– 100% of circuit designed, 50% of breadboard completed

• Need 100% events– Module 100% breadboard,

subsystem testing complete• Need critical path chart

– Parts on availability!– Know effects of slippage– Know what to work on when

35% Planning(not all up front)

15% breadboarding

25% moduletest/dubug

25% systemtest/debug

Provide a 4‐7 day contingencyto deal with unforeseen issues

(you’ll use it all!)


Choosing A Topic• You only have 6 weeks total (once your proposal abstract is turned in)

to do this project.– It is important to complete your project.– It is very difficult to receive an “A” in the class without having something working for the final project.

• The complexity for each team member should 4‐5 times the complexity of the lab assignments.

• Some projects include digital building blocks or mechanical assemblies (infrared, wireless, motors, etc.). However, keep in mind that this is an analog design class and your design will be evaluated on its analog design aspects.

• Complexity, risk and innovation factor.– We will give credit to innovative applications, design approaches– More complex is not necessarily better


Project Grading (High Level)

• Functionality grading– But it works in LTspice: grade 0%– Unable to demo/test because my partners’ module isn’t

working: grade 0%

• General project grading guidelines– approximately 2x hardest lab: grade 8‐15– Demonstrates a superior understanding of circuits and

implementing complex design ‐ perhaps with interface to external devices, multiple voltages, RF, extremely low signal levels audio, etc. The implementation goes beyond what was in the labs. 16‐25

– a top notch project that really stands outs with complexity, innovation and risk 26‐32


Guidelines• Use of integrated circuits

– Acceptable when integrated circuit is a component but not the main function of a system

• VCO (voltage controlled oscillator) as part of a spectrum analyzer

• Linear voltage regulator in deriving 3.3v from 5v

– Not acceptable:• 10 watt audio amplifier with 4 watt IC and push pull

amplifier• RF transmitter with function generator as RF source

• Through hole or surface mount parts!• Breadboard before laying out PCB.


Voltmeter ExampleTeensy + digital display

• F: Teensy with external ADC IC• D: same as above but with discrete linear PS.• C: ADC implemented with op‐amps and 555 ramp• B: discrete design (except for display); self zero offset calibration

• A: above design plus energy scavenged power discrete design or powered by 1.5V AA battery


Thermin


Bass Guitar Effects Bank


Analog Guitar Hero


Character Generator


Projects Ideas• Pure Circuit

– RF Powered Receiver– RLC Meter– BJT/MOSFET testor– Battery testor (internal resistance)– 1.5‐9V high efficiency USB charger

(discrete components)– Discrete AD Converter– Home‐made accelerometer– Home‐made Fitbit– Character generator

• Practical/Fun– Talking Robot (moving

mouth/lights)– Switchless home lighting control

system– Acceleromter/tilt game


• Sensor based– Balanced beam– Body power ECG AM transmitter– Road tracking model car– Analog servo controller– Romba robot– Electronic seismograph

• Optics– Audio over Fiber (Digital)– Audio over Fiber (Analog)– Laser based voice snooper

Test Equipment Projects

• Zener diode curve oscilloscope display (2 person)• BJT/MOSFET Curve tracer

– 2 person: use oscilloscope as XY display– 3 person: autosensing BJT/MOSFET, auto lead identification

• Tek 575 Curve Tracer Replacement– autosensing BJT/MOSFET, auto lead identification– Self contained with FPGA and VGA display


Analog Text Generator


Some Suggestions• Be ambitious!

– But choose a sequence of milestones that are increasingly ambitious (that way at least part of your project will work and you can debug features incrementally).

– But don’t expect 100+Mhz operating frequencies without problems!

• It’s motivating if there’s something to see or hear or move– Sound, light and motor projects are fun

• High frequency (>100Mhz) circuits are often the limiting factor


More Suggestions

• Be modular!– Figure out how test your modules incrementally (good for

debugging and checkoff!)– Be clear about signals, voltage levels, frequency passed

between modules

• Don’t be caught by the mañana principle– Six weeks goes by quickly: have a weekly task list.– How does a project run late: one day at a time!– Effort is not the same as progress: “designed but not built” only

means you’ve made a start– Tasks will take longer than you think– Final integration will uncover bugs and noise so test module‐to‐

module interactions as early as you can


Project Grading (32 points Total)• Deadlines and Participation (7 points)

• Problem Definition and Relevance, Architecture, Design methodology (9 points)– What is the problem– Why is it important– System architecture and partitioning– Design choices and principles used– Circuit design and layout– All of the above should be stated in the project and report

• Functionality (8 points)– Did you complete what you promised (i.e., graded by the checklist)

• Complexity, Innovation, Risk (8 points)6.101 Spring 2020 54Lecture 10

Grading

6.101 Spring 2020 55

A large number of students do "A" level work and are, indeed, rewarded with a grade of "A". The corollary to this is that, since average performance levels are so high, punting any part of the subject can lead to a disappointing grade.

Homework 10%

Quiz 10%

Labs 30%Project 32%

CIM 15%

Participation 3%

Lecture 1

CIM Grading (15 points Total)

• Final report– 5% technical content

• Overview• Circuit detail• Measurements• Error analysis• Conclusions/lessons learned

– 10% writing


Printed Circuit Boards

• PCB optional for final project

• Department will fund reasonable size two layer PCB– Example: 2.5” x 4” PCB

• Popular software: Altium, KiCad, Eagle, Expresspcb


Design Suggestions

• Know specifications of devices• Use bypass caps liberally• Use ground plan for high frequencies >10mhz • Keep signal wires short• Beware of parasitic capacitance and inductance –wire, etch; components are not ideal!


2020 design question - mit6.101 spring 2020 lecture 10 2 2020 design question •when landline...

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