Question 17.2: Repeat the investigation of Example 17.1 using a simplified ......

We have looked at three simplified models for the diode.

If we assume that the diode is ‘ideal’, there is no voltage drop across the diode and the current in the circuit is given by I = E/R = 5 V/1000 Ω = 5 mA.

If we include the effect of the conduction voltage of the diode, then the current is given by I = (E  –  V_{D})/R = (5  –  0.7)/1000 = 4.3  mA.

If we include the effect of the conduction voltage and internal resistance of the diode, then the current is given by I = (E  –  V_{D})/(R + r_{ON}) = (5  –  0.7)/(1000 + 10) = 4.26  mA.

You might like to compare these three results with the value obtained using a graphical approach in Example 17.1.