Understanding the Load Line Concept in Electronics: Explained

[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 can't seem to find a decent link on this topic...

Any help would be great...

thanks

-jake

 

[quantumdude]

Is this what you area talking about?

http://hyperphysics.phy-astr.gsu.edu/Hbase/electronic/loadline.html

Or are you talking about an ideal voltage source applied to a load of adjustable impedance, in which the transmission line also has a non-negligible impedance?

 

[peejake]

http://hyperphysics.phy-astr.gsu.edu/Hbase/electronic/loadline.html

hey tom

thanks for replying,

i am talking about the link you gave me...can u please explain it to me as according to my question if you don't mind...

cheers
jake

 

[berkeman]

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...

 

[peejake]

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...

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...??

 

[berkeman]

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...??

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

 

[peejake]

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

cheers
jake