Transforming a switch into a voltage source

[nhrock3]

http://i47.tinypic.com/4pxbte.jpg

i can't understand upon what bais they made such a transition

?

 

[berkeman]

http://i47.tinypic.com/4pxbte.jpg

i can't understand upon what bais they made such a transition

?

What is that thing? A 12uV voltage source backwards? Or is it supposed to represent the final current through the inductor?

 

[nhrock3]

its some step function
which represents a voltage sorse
-t says its zero from t>0 and forward

 

[berkeman]

its some step function
which represents a voltage sorse
-t says its zero from t>0 and forward

Oh, so it's meant to replace the switch with a step function. Okay.

 

[nhrock3]

its acts like a switch
its a step function of -t

from t>0 and forward it goes to zero like a switch

but how they got its coefficient of the step function?

i can't see how its the same as the original circuit
??

 

[berkeman]

It looks to me like it generates a 12V that is opposing the other 12V supply, up until t=0 when it goes off and let's the other 12V supply be the only supply in the circuit. for t<0 when the two 12V supplies oppose each other, there is no net voltage to drive a current around the circuit.

 

[nhrock3]

can you describe how its like the original circuit?

 

[nhrock3]

how its opposing ??

its plus 12
not minus 12

 

[nhrock3]

ahh thanks :)