SMV ELECTRIC TUTORIALS Nicolo Maganzini, Geronimo Fiilippini, Aditya Kuroodi 2015

OPERATIONAL AMPLIFIERS

What are we learning?  Learning about operational amplifiers  What they do and how they are used.  Increasing signal strength and filtering. Medical station pulse sensor.  Learn about how they are nearly ideal for DC amplification.  Learn about different Op-Amp circuits:  Inverting  Noninverting  Voltage Follower (Buffer)

Op-Amp connections  Three-terminal device:  Inverting input (-)  Noninverting input (+)  Output  Power supply + lead (+ Vss)  Power supply – lead (- Vss) 4

Real device 5

What does it do? 6

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Biasing circuits 9

But first, some properties 10

Inverting amplifier 11

Non-inverting amplifier 12

Buffer amplifier 13

Buffer Circuit Project  Use a 9V battery to make a potential divider that makes a 4.5V signal. Use 1KOhm resistors.  Now use that signal to drive a fan.  While the fan is connected, measure the voltage of the signal. Has it changed? Is it still constant? Why?  Take notes on what you do and what the answer is on a piece of paper. 14

Continued  Now using the same potential divider, add a buffer to the signal and then drive the fan with the buffer. Power it with another battery. 15

How about using our photosensor? 16  Replace resistor with photocell.  Will the motor turn on when photocell is covered or uncovered?  Can you change that behavior?

DIGITAL AND ANALOG SIGNALS

BREADBOARDING Breadboard is a way of constructing electronics without having to use a soldering iron.

SOLDERLESS BREADBOARD What a solderless breadboard looks from the inside.

SIGNALS A signal is any kind of physical quantity that conveys information. Audible speech, hand gestures, sound, light, pressure, electrical signals In circuits, the word signal will be used in reference to an electrical quantity of voltage or current that is used to represent or signify some other physical quantity. Signal from a thermometer, sound sensor, GPS, light sensor Two main types of signals Analog signals Digital signals

ANALOG AND DIGITAL SIGNALS AnalogDigital Continuous (no breaks or interruptions) Not continuous. Use specific values to represent information. Examples: music from speakers Examples: Light turning on and off Computer signals

ANALOG AND DIGITAL SIGNALS Is this a digital signal?? Even though this signal has more than two possible values (unlike the one on the previous slide), it is still considered a digital signal because only a finite amount of values are allowed.

ANALOG AND DIGITAL SIGNALS Converting from analog to digital (ADC) Trying to represent analog signal as best as we can using “discrete” values.

SIGNAL FREQUENCIES AND PERIODS

We can also get the period from the plots, by measuring how long it takes for the signal to complete one cycle.

EXCERCISE: Calculate period and the fundamental frequency of the following signal: