# Simple Diode Circuit Help

Discussion in 'Homework Help' started by fiz, Oct 16, 2006.

1. ### fiz Thread Starter New Member

Oct 16, 2006
2
0
I am having a hard time grasping how to simplify circuits with diodes (assuming a piecewise linear model w/ a turn on voltage of 0.7 V). I have attached a picture of a circuit with a 2 diodes in series and 3 other resistors in the circuit. I am having trouble trying to figure out where to start to calculate I1. I want to add resistors to simplify but none are in series or parallel. Any help would be appreciated.

Edit: Sorry it's hard to read, R1 and R3 have values of 1k Ohms and R2 is 500 Ohms.

2. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Hi,

It's a pretty simple series-parallel circuit. The two diodes drop 1.4 volts off the voltage that would normally be across R2. Otherwise, it's just a series resistance and two parallel branches.

3. ### fiz Thread Starter New Member

Oct 16, 2006
2
0
Ah, thanks. To make sure just simplify the circuit as if the diodes aren't in it, as in add R1 and R2 and then take that value and add it to R3 (1/R1+R2 + 1/R3)^-1 then use that resistance value to get I1? If my thinking is right I can figure out the rest.