Block Diagram trouble

Thread Starter


Joined Nov 2, 2009
Hi there,
This is my first post, but I'm sure I'll be dropping into the forums more often, they seem to be a lot of help.

I've been having trouble with a particular question in one of our assignments. We have been given the circuit diagram for a RLC circuit (see attachment circuitdiag.PNG) and have been told to draw a block diagram from this circuit in terms of the S-domain so that in later use we can derive the transfer function for the system.

Problem is, I have drawn what I believe the block diagram was (see attachment blockdiag.PNG), I emailed it to my lecturer for him to look at to clarify it was correct. His repsonse was that the diagram was incorrect, he said that the "20s" shouldn't be leading into a positive part of the summing junction. I can't see how the block diagram should look. He refused to give me any more guidance because he'd have to penalise me.

Can someone help me in drawing the correct block diagram?

Thank you,

EDIT: Sorry if I posted into the incorrect thread section.



Joined Mar 6, 2009
Can anyone help?
Hi cold.clown,

You need to post your solution methods for

1. Derivation of the Laplace form of the circuit transfer function G(s)=Vo(s)/Vi(s)

2. Your state-space representation (based on 1.) for / from which the block diagram was developed.