11. Pulse generator

Question 1

Describe two-state system

Answer 1

Transition between the resting and activated states is induced by a trigger pulse exceeding the threshold level.

Question 2

two-state system

What is forbidden state?

Answer 2

The state between the resting and activated states

→ it will fall into either of the two permitted ones

Question 3

two-state system

Transition between the two states is always evoked by a (1)___,

Answer 3

Signal

-> a pulse that exceeds some threshold level (the falling edge of this pulse may also work).

Question 4

two-state system

What is a trigger pulse?

Answer 4

a pulse that exceeds some threshold level (the falling edge of this pulse may also work).

Question 5

What are the three types of pulse generators

Answer 5

monostable, astable and bistable multivibrator

Question 6

How many stable states does monostable multivibrator have?

Answer 6

1

Question 7

How many stable states does astable multivibrator have?

Answer 7

0

Question 8

How many stable states does bistable pulse generator have?

Answer 8

2

Question 9

Descrive monostable multivibrator

Answer 9

pulse generator producing a single output pulse of determine duration, for every input pulse (trigger) above a threshold.

Question 10

monostable multivibrator

Other names for monostable multivibrator?

Answer 10

one-shot or monoflop

Question 11

monostable multivibrator

Triggered by an input pulse, it gives a ___(usually square pulse) of determined duration (Fig. 2)

Answer 11

single output pulse

Question 12

monostable multivibrator

What is the usual type of pulse of single output pulse?

Answer 12

usually square pulse

Question 13

monostable multivibrator

The rising edge of the square pulse is induced by the (1)____, but the system returns spontaneously without further (2)___ to its (3)___ (via a dropping edge) after (4)____

Answer 13

1. trigger signal
2. triggering
3. stable state
4. the time given by the time delay (􏷑T ).

Question 14

Give an example of monostable multivibrator

Answer 14

Defibrillator

Question 15

Defibrillator

Let us take a closer look at the possibility of electronic timing (setting the delay time 􏷑 ) with regards to the defibrillator

→ The resistance of the chest is R, at which the capacitor of capacitance C is discharged.

→(1)____flows through the resistance R, and we encounter a (2)___ of similar shape.

Answer 15

1. Exponentially decreasing electric current (I)
2. voltage U decrease

Question 16

Defibrillator

Principle of operation of the defibrillator?

Answer 16

Electric pulses with higher energy can be applied with the aids of electrodes placed on the chest

-> generates the synchronized contraction of the heart with the chance to restore the normal heart pace

(The time constant of the pulse can be set by the R (The resistance of the chest) and C (capacitance) elements of the circuit.)

Question 17

monostable multivibrator

In electronics, the timing of a monostable multivibrator is usually realized by an ___ circuit

Answer 17

RC

Question 18

monostable multivibrator

In electronics, the timing of a monostable multivibrator is usually realized by an RC-circuit

The (1)___ of a discharging capacitor controls a switching circuit, which turns on and off according to (2)____

→ we obtain a (3)___ pulses of (4)___, set by the values of R, C and/or the trigger level.

Answer 18

1. exponentially decreasing voltage
2. the trigger voltage level
3. square
4. controlled durations

Question 19

Describe astable multivibrator (relaxation oscillator, free-running multivibrator)

Answer 19

• Pulse generator producing a sequence of identical pulses.
• It can be constructed by connecting two monostable multivibrators in a ring.

Question 20

astable multivibrator (relaxation oscillator, free-running multivibrator)

By connecting two (1)____ in a ring (Fig. 5), we get the astable multivibrator (AMV)

Answer 20

monostable multivibrators (MMV)

Question 21

astable multivibrator (relaxation oscillator, free-running multivibrator)

Other names of astable multivibrator

Answer 21

free-running multivibrator or relaxation oscillator

Question 22

astable multivibrator (relaxation oscillator, free-running multivibrator)

The output of the (1)____ (see Fig. 2, falling edge) triggers the (2)____, which subsequently triggers the (3)___ and this process continues on and on.

Answer 22

• first MMV (monostable multivibrators)
• second MMV
• first MMV

Question 23

astable multivibrator (relaxation oscillator, free-running multivibrator)

The output of the first MMV (see Fig. 2, falling edge) triggers the second MMV, which subsequently triggers the first MMV and this process continues on and on. This way we get a ___

Answer 23

periodic square pulse generator

Question 24

astable multivibrator (relaxation oscillator, free-running multivibrator)

How to calculate the time period of the AMV?

Answer 24

the sum of the individual active-state durations of the MMV1 and MMV2

Question 25

**_astable multivibrator (relaxation oscillator, free-running multivibrator)_** The pulse width of the two MMV-s can be adjusted individually by their (1)\_\_\_ elements → a square pulse train of any (2)\_\_\_ can be produced

Answer 25

1. *RC* 2. **duty cycle**

Question 26

**_astable multivibrator (relaxation oscillator, free-running multivibrator)_** What is the role of duty cycle?

Answer 26

It determines what portion (percentage) of the time period is occupied by the pulse itself, thus by the activated state

Question 27

**_astable multivibrator (relaxation oscillator, free-running multivibrator)_** What is the formula of duty cycle?

Answer 27

For the duty cycles of the output signals *U*_{out 2} (see Fig. 5), we obtain:

Question 28

**_astable multivibrator (relaxation oscillator, free-running multivibrator)_** The contractions of a healthy heart are controlled by electrical pulses similar to those produced by the AMV-s. → There are several cells that create these stimuli **Q's: Give examples for these cells**

Answer 28

sinoatrial node (SA node), atrioventricular node (AV node), and the cardiac muscle cells themselves → These are called pacemaker cells,

Question 29

What are pacemaker cells?

Answer 29

**The cells that create electrical pulses, setting the pace for blood pumping for heart contraction -\>** directly control the heart rate

Question 30

The role of an **artificial pacemaker**

Answer 30

It is implanted in order to restore the normal heart rate.

Question 31

**_artificial pacemaker_** The pacemaker itself provides an (1)\_\_\_ function for a slow or irregular "biological astable multivibrator" (the heart) in order to induce (2)\_\_\_

Answer 31

1. artificial trigger 2. contractions at the proper rate

Question 32

Describe **bistable multivibrator**

Answer 32

„pulse generator” that requires an input pulse (trigger) for the activation of either of the two stable states. By connecting several bistable multivibrators in an array, a binary counter array may be constructed.

Question 33

Other names for **bistable multivibrator**

Answer 33

* flip-flop * biflop

Question 34

**_bistable multivibrator_** The trigger pulse induces a \_\_\_

Answer 34

change of the state of the bistable multivibrator

Question 35

**_bistable multivibrator_** The trigger pulse induces a **change of the state of the bistable multivibrator.** What does this mean?

Answer 35

If it was in the state A before, then it is flipped into state B; and if it was in state B then it is flipped into the state A, and will remain in either state indefinitely, unless triggered again

Question 36

**_bistable multivibrator_** The trigger pulse induces a **change of the state of the bistable multivibrator.** This circuit has two equivalent, What are these equivalents?

Answer 36

2 stable states

Question 37

Application of bistable multivibrator

Answer 37

Application: on/off switches and memory units.

Question 38

Application of monostable multivibrator

Answer 38

Defibrillator

Question 39

Application of bistable multivibrator

Answer 39

Pacemaker

Question 40

Parameters of a pacemaker pulse

Answer 40

Period: approx. 1 sec Amplitude: 0.8-5 V Duty Ratio: Active time/total period Energy: V^2/R(tissue)

Question 41

142. Describe a pulse signal.

Answer 41

A single jump of signal to higher amplitude and then back to the normal baseline.

Question 42

Calculation of pulse energy

Answer 42

*Known voltage and tissue resistance, known pulse duration time* * Proportional to voltage and pulse duration period * Inversely proportional to tissue resistance (**A LONG lasting battery is needed.** **A battery change = exchange of the whole device = operation!)**

Question 43

Pacemaker Function codes of Chamber(s) Sensed

Answer 43

Question 44

What is five letter code of pacemaker?

Answer 44

The first letter represents the cardiac chamber paced (A for atrium, V for ventricle, D for dual). The second letter represents the chamber sensed (A for atrium, V for ventricle, D for Dual, and O for none).

Question 45

Pacemaker Function codes of Chamber(s) Paced

Answer 45

Question 46

Pacemaker Function codes of Response to Sensing

Answer 46

Question 47

Pacemaker Function codes of Rate Modulation

Answer 47

Question 48

Pacemaker Function codes of Multisite Pacing

Answer 48

Question 49

What is Betavoltaic cell?

Answer 49

β-radiation powered cell. * the ionization separates charges in a semiconductor junction