# Diode voltage measurement

Discussion in 'Electronics Homework Help' started by Joe Bachi, Oct 12, 2013.

1. ### Joe Bachi

21
0
Feb 3, 2013
Hey guys,
I ran the following simulation on Multisim and got the following results:

When the function generator is set at an amplitude of 10 V, the voltage drop across the diode is -20 V
Why is that? Shouldn't it be -10 V ?

2. ### Harald KappModeratorModerator

10,820
2,440
Nov 17, 2011
I don't know multisim. Real world function generators typically have an internal output resistance of 50Ohm to match impedances in typical rf circuits. The output voltage you can set assumes correct termination with a resistor of the same resistance (50Ohm). The internal resistor and the load make a voltage divider (1/2). Thus the open circuit voltage of the generator (no load resistor or load resistor >> internal resistor) is twice the voltage you set at the function generator's panel.
Check this in multisim by looking up the data of the function generator and/or measuring at the output of the generator witout a load and witha a load of 50 Ohm.