# Homework Help: Load Line in Electronics

1. May 20, 2006

### peejake

Hey everyone,

I need some help here.......

My question is:

When a variable load is applied to a real source , explain the concept of a load line?? This is the load line in electronics...can someone please help me out with it.....i cant seem to find a decent link on this topic...

Any help would be great...

thanks

-jake

2. May 21, 2006

### Tom Mattson

Staff Emeritus
3. May 22, 2006

### peejake

4. May 22, 2006

### Staff: Mentor

The load line shows the V-I characteristic of the circuit, with the variable load being the thing that varies to trace out the line. As Vce in the circuit shown varies from 0 to Vbb, you get more or less current, following the line. So as the transistor in the circuit varies, you get an Ic that varies with Vce. I'm not sure that explanation helps you any more than you already understand -- just think of the load line as the constraint of the external circuit on the element that will be varying....

5. May 22, 2006

### peejake

so does this mean that the load line actually shows how much the circuit or the components can tolerate before it actually burns out or shorts...??

6. May 22, 2006

### Staff: Mentor

It's part of it. For transistor damage, you need to look at the "Safe Operating Area" of the transistor that you're using. You can find this info on the datasheet of most power transistors, for example. It involves load line concepts, and also the concept of time.

I googled load line transistor power +"safe operating area", and got lots of hits. Here's the first one -- pretty nice discussion:

http://sound.westhost.com/soa.htm

Last edited by a moderator: Apr 22, 2017
7. May 24, 2006

### peejake

I got it.....
thanks for the link berkeman.....

cheers
jake