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Flashcards in Electronics Deck (49):
1

Define Ampere

Unit of electric current (flow of 1 coulomb per sec)

2

Define Coulomb

Unit of electric charge

3

define Ohm

Unit of electric resistance

4

define Volt

Unit of electric potential and electromotive force

5

define Hertz

Unit of frequency

6

define Farad

Unit of capacitance (Ability of body to store charge)

7

Ohms law is

V = IxR

8

Define Joules

Unit of Energy (1J per second = 1 Watt)

9

Energy equation is

E = V x I x T

10

What is slew rate

dV/dT (A >0.5vS // V>0.75vS)

11

What is a pacemaker can made of

Titanium

12

What is the battery made of

Lithium Iodine from 1975

13

Benefits of lithium iodine

Long shelf life
Predictable decay for 90% of battery life
Hermetically sealed in device
Capacity between 0.8 and 2.5aH

14

What voltage can todays battery generate

2.8V

15

What are ICD batteries made of

Silver vanadium oxide

16

What voltages can ICD batteries generate

3.2V

17

Internal resistance on ICD batteries remains low (maintaining consistent charge times) till what percent of discharge

80%

18

How to calculate longevity

(114 x Battery capacity Ahr) / Current drain (uA)


19

Calculate energy use

(Voltage squared / resistance) x pulse width

20

What is ROM responsible for

Output
Sensing
Pacemaker Codes

21

What is RAM responsible for

Pacing rate
Sensor outputs
Diagnostic storage (Histos / Trends etc)

22

How are capacitors charged and dissipated

Charged in parallel

Dissipated in series

23

Double voltage output, _______ increase energy drain

Four fold increase

24

What frequency do bandpass filters normally allow

20-40Hz

25

What does a Zener diode do?

Protects integrated circuit from high external voltages (Defib)

26

What happens when the voltage exceeds the Zener voltage

Energy is shunted back down the leads to myocardium

27

What voltage may result in an ICD not being able to deliver a shock

<1.5V

28

Storing 40J of energy drains the battery of how much energy?

80J (Double)

29

Capacitance is directly proportional to.....

The surface area of each conductor

30

Capacitance is inversely proportional to.....

The distance separating the two conductors

31

What are ICD capacitors rated at (in farads)

90-150 microfarads

32

What is a key determinant of ICD size?

The amount of stored energy (capacitor size)

33

Voltage stored on the capacitor is equal to initial shock waveform --- TRUE/FALSE

True

34

Waveform tilt is normally at what percentage

50%

35

How much lower are DFTs with biphasic vs Monophonic shocks

30-40%

36

What is the energy density of the two types of capacitors

Aluminium = 3j/cm3

Tantalum = 5j/cm3

37

What is the energy density of a battery

>3000J/cm3

38

Are the Aluminium/Tantalum capacitors Anodes or Cathodes

Anodes (Positive electrode)

39

Have a higher energy density but that density means they can't be charged to as high voltage ------ which capacitor material

Tantalum

40

ICDs have how many of each capacitor generally (Either/Or - not mixed)

Either

2x Aluminium

3 or 4x Tantalum

41

What is a typical leading edge shock voltage

750-900V

42

Which material do you need to periodically charge

Aluminium - Imperfections in foil opens up and charge leaks

43

The leads in aluminium capacitors accounts for longer charge times by what percentage

20-50%

44

Charge time delays <50% could be caused by what

Dielectric leakage (aluminium cracks)

45

Charge time delays >50% could be caused by what

Due to battery voltage delay (mid life)

46

When capacitor is charged after long period - it seals the dielectric leads -- TRUE OR FALSE

True - Capacitor reformation

47

How often should you perform a capacitor reform

6 months

48

Can therapeutic or aborted shocks reform the capacitors

No - it must be charged and maintained for several minutes

49

Capacitor reform consumes how much of the battery total

0.5 to 1%