IV Characteristics of Simple Diode Circuits

[Master J]

I'm trying to figure out what the IV characteristic curves are of some simple diode circuits.

A) Diode and resistor in series.

B) Diode and resistor in parallel

C) Diode and resistor in parallel, and this combo in series with another diode reversed wrt. first diode.

Its been a while since I've looked at diodes...Im not certain which way to approach this.
Any help on getting me in the right direction would be very much appreciated!

Thanks!

 

[vk6kro]

You could consider what happens when the diode is fully conducting. It then has about 0.7 volts across it and any resistors will be obeying Ohm's Law.
EDIT.
Suppose you put a diode and a resistor in series and assume a diode with 0.6 volts across it when it is conducting, and a 100 ohm resistor.

Input volts 0.1
Volts across diode 0.1
Voltage across resistor = 0
Current in resistor = 0

Keep doing this in steps of 0.1 volt

Input volts 1
Volts across diode 0.6 V
Voltage across resistor = 0.4 V
Current in resistor = 0.4 V / 100 ohms = 4 mA
Current in diode = 4 mA

If you do this, you can then draw a graph of the results.

 

[pantaz]

Here's a page of links to helpful resources:
http://amasci.com/elehob/elehobed.html