Question

You are tasked with designing a defibrillator with the following specifications:

a) The defibrillator is modelled as a simple 1st order LTI system. The resistor in the charging circuit is 20k ohm.

b) Charging time (from “empty”) is no more than 4 s from the moment the “charge” button is pressed to be within 2% of full charge value.

c) The system allows the delivery of either 50, 75 or 125 J of energy to the patient.

d) The patient is modelled as a 50 ohm resistor.

Calculate the following:

i) Draw one or two circuit(s) representing the 2 situations: charging the capacitor and discharging (defibrillating the patient’s heart).

ii) What size capacitor is needed to achieve these specifications?

iii) Calculate the voltage supply needed to deliver the different amounts of energy specified above.

iv) How long does it take to deliver 99% of the charge to the patient? Hint: energy is the integration of power.

v) Calculate the current flowing through the patient for each energy level as a result of defibrillation.

Answer 1