# Transforming a switch into a voltage source

1. Jan 19, 2010

### nhrock3

2. Jan 19, 2010

### Staff: Mentor

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

3. Jan 19, 2010

### nhrock3

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

4. Jan 19, 2010

### Staff: Mentor

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

5. Jan 19, 2010

### 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 cant see how its the same as the original circuit
??

6. Jan 19, 2010

### Staff: Mentor

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 lets 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.

7. Jan 19, 2010

### nhrock3

can you describe how its like the original circuit?

8. Jan 20, 2010

### nhrock3

how its opposing ??

its plus 12
not minus 12

9. Jan 20, 2010

### nhrock3

ahh thanks :)

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook