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