Week 2

Question 1

Resistors use

Answer 1

• Limiting current
  • Regulating voltages
  • Generating heat (special resist

Question 2

Resistance formulas

Answer 2

R = V / I
In series Rtot = R1 + R2…
In parallel 1/Rtot = 1/R1 + 1/R2

Vout = Vin * R2/(R1+R2)
voltage over resistors is equal in a voltage divider

Question 3

resistor strength

Answer 3

last one is tolerance/accuracy, second to last is number of zeroes. the rest is the rest of the numbers

Question 4

Diode

Answer 4

conducts in one direction block the other > trafic control
useful when converting AC to DC

Question 5

LED

Answer 5

light emitting diode

Vled = Vsource - VR
P = Vled * I

forward voltage 1.2-3.6 forward current 10-30mA

Stretching limits = breaking LED

Question 6

Capacitator

Answer 6

storage of electrical charge/energy, it is not a battery but for short & fast charge
capacity is measured in Fahrad
do not switch poles

Question 7

What is a capacitator useful for

Answer 7

• For smoothing/short term energy storage (e.g., fluctuating power supply)
• For filtering (e.g., for blocking low/high frequency signals)
• For power bursting (e.g., defibrillators, pulsed lasers, particle accelerators)
• For power outage handling (e.g., powering your circuit just long enough to save status

Question 8

transistor

Answer 8

‘active’ component, acts like ‘valves’ in a circuit, has two main types: BJT and FET

usefull when wanting to sswitch things on and of, amplify a signal or build logic

Question 9

difference BJT and FET

Answer 9

BJT: current controled, linear relation I/o, low current applications, slow, cheap, robust
FET = other way around

Question 10

How does switching work transistors

Answer 10

control pin, load, ground
BJT: Base, collectot, Emitter
FET: gate, drain, source

Question 11

important transistor concepts

Answer 11

hFE : current gain / ‘amplification factor’
* E.g., for BJTs, h FE=100 means ICE = 100*IBE
* Saturation: the amount to which a transistor is ‘open’
* For amplification, you might want to avoid ‘full saturation’
* For switching, you want ‘full saturation

Question 12

how to find the right resistor

Answer 12

for a constant load > BJT
for variable load or energy efficient > FET

Question 13

buttons

Answer 13

make or break a connection, can be momentary or latching, most mechanical buttons bounce

usefull when turning prototype on or off (latching), resseting a circuit (momentary, user input (momentary) and mode selection (latching switch)

debouncing is someties necessary

Question 14

potentiometers

Answer 14

variable resistors, has three pins to allow for voltage dividing.

used for fine analog input, volume, brightnes of light etc.

Question 15

important pot meter concepts

Answer 15

variable resistance > can cause led to burn > use practice resistor

Question 16

LDR

Answer 16

light dependent resistor, more light = less resistance.

Always check range accuracy and tolerance for your requirements

Question 17

NTC/thermistor

Answer 17

temperature meter, the resistance is relative to temperature, temperature rises>resistance lower.

Question 18

NTC concepts

Answer 18

always check range, accuracy and tolerance for requirements. Mind that current flowig through the ntc heats up

Question 19

how to use an NTC

Answer 19

need a voltage divider, constructed by two resistors.

Question 20

pietzo disc

Answer 20

converts mechanical to electrical energy and vice versa.

Detect vibrations, can ditect loud sounds, can be used as contact microphones, drum trigger, output sound, haptic feedback, some generate mist

Question 21

non-blocking

Answer 21

for example output pietzo sound: it will continue to ouput sound even if it is not finished playing the last tone