diff --git a/opamp_circuits_C_GARRETT/circuit1001.png b/opamp_circuits_C_GARRETT/circuit1001.png
index c626ebf..7652287 100644
Binary files a/opamp_circuits_C_GARRETT/circuit1001.png and b/opamp_circuits_C_GARRETT/circuit1001.png differ
diff --git a/opamp_circuits_C_GARRETT/opamps.tex b/opamp_circuits_C_GARRETT/opamps.tex
index 1259312..aa4e02c 100644
--- a/opamp_circuits_C_GARRETT/opamps.tex
+++ b/opamp_circuits_C_GARRETT/opamps.tex
@@ -21,10 +21,12 @@
 
 \begin{abstract}
 Circuits from email conversation.
+
 Not a document to be proof read.
+
 Proof of analysis concept.
 
-Function fm() applied to a component returns its failure modes.
+Function $fm$ applied to a component returns its failure modes.
 \end{abstract}
 \clearpage
 \section{Op-Amp circuit 1}
@@ -39,7 +41,7 @@ Function fm() applied to a component returns its failure modes.
 
 
 The amplifier in figure~\ref{fig:circuit1} amplifies the difference between 
-the voltages $+V1$ and $+V2$.
+the input voltages $+V1$ and $+V2$.
 It would be desirable to represent this circuit as a derived component called say $DiffAMP$.
 We begin by identifying functional groups from the components in the circuit.
 
@@ -47,7 +49,7 @@ We begin by identifying functional groups from the components in the circuit.
 \subsection{Functional Group: Potential Divider}
 
 R1 and R2 perform as a potential divider.
-Resistors can fail OPEN and SHORT.
+Resistors can fail OPEN and SHORT (according to GAS burner standard EN298 Appendix A).
 $$ fm(R) = \{ OPEN, SHORT \}$$
 
 
@@ -71,18 +73,18 @@ $$ fm(R) = \{ OPEN, SHORT \}$$
 \label{tbl:pdfmea}
 \end{table}
 
-By collecting the symptoms in table~ref{tbl:pdfmea} we can create a derived
+By collecting the symptoms in table~\ref{tbl:pdfmea} we can create a derived
 component $PD$ to represent the failure mode behaviour
 of a potential divider.
 
 Thus for single failure modes, a potential divider can fail
-$fm(PD) = \{PDHigh,PDLow\}$.
+with $fm(PD) = \{PDHigh,PDLow\}$.
 
 
 The potential divider is used to program the gain of IC1.
-IC1 and PD1 provide the function of buffering
+IC1 and PD provide the function of buffering
 /amplifying the signal $+V1$.
-We can treat IC1 and PD1 as a functional group.
+We can now examine IC1 and PD as a functional group.
 
 
 \subsection{Functional Group: Amplifier}
@@ -100,7 +102,7 @@ a functional group we can analyse its failure mode behaviour.
 
 
 \begin{table}[ht]
-\caption{Non Inverting Amplifier: Failure Mode Effects Analysis: Single Faults} % title of Table
+\caption{Non Inverting Amplifier $NI\_AMP$: Failure Mode Effects Analysis: Single Faults} % title of Table
 \centering % used for centering table
 \begin{tabular}{||l|c|c|l|l||}
 \hline \hline
@@ -124,7 +126,7 @@ a functional group we can analyse its failure mode behaviour.
 
 Collecting the symptoms we can see that this amplifier fails
 in 3 ways $\{ AMPHigh, AMPLow,  LowPass \}$.
-We can now create a derived component, $NONINVAMP$, to represent it.
+We can now create a derived component, $NI\_AMP$, to represent it.
 
  
 $$ fm(NI\_AMP) = \{ AMPHigh, AMPLow, LowPass \} $$
@@ -138,7 +140,8 @@ The second stage of this amplifier, following the signal path, is the amplifier
 consisting of $R3,R4,IC2$.
 
 This is in exactly the same configuration as the first amplifier.
-Its failure mode are therefore the same.
+Its failure modes are therefore the same. We can therefore re-use
+the derived component for $NI\_AMP$
 
 \pagebreak[4]
 \subsection{Modelling the circuit}
@@ -161,9 +164,9 @@ two derived components of the type $NI\_AMP$.
  TC1: $NI\_AMP1$ AMPHigh        &  opamp 2 driven high          &      & DiffAMPLow \\ 
  TC2: $NI\_AMP1$  AMPLow        &  opamp 2 fdriven low          &      &  DiffAMPHigh \\  
  TC3: $NI\_AMP1$ LowPass        &  opamp 2 driven with lag      &      &  DiffAMP\_LP \\  \hline 
- TC4: $NI\_AMP2$ AMPHigh        &  dual amplifier high           &      &   DiffAMPHigh\\  
- TC5: $NI\_AMP2$ AMPLow         &  dual amplifier low              &      &  DiffAMPLow \\  
- TC6: $NI\_AMP2$ LowPass        &  dual amplifier lag/lowpass        &      &  DiffAMP\_LP \\ \hline 
+ TC4: $NI\_AMP2$ AMPHigh        &  Diff amplifier high           &      &   DiffAMPHigh\\  
+ TC5: $NI\_AMP2$ AMPLow         &  Diff amplifier low              &      &  DiffAMPLow \\  
+ TC6: $NI\_AMP2$ LowPass        &  Diff amplifier lag/lowpass        &      &  DiffAMP\_LP \\ \hline 
  %TC7: $R_2$ OPEN     &  LOW       &      &  LowPD \\ \hline
 \hline
 \end{tabular} 
@@ -180,11 +183,20 @@ We now create a derived component to represent the circuit in figure~\ref{fig:ci
 $$ fm (DiffAMP) = \{DiffAMPLow, DiffAMPHigh,  DiffAMP\_LP\} $$
 
 
-Its interesting here to note that we can draw a directed graph
-of the failure modes and derived components here.
-By doing this we can trace any top level fault back to 
+Its interesting here to note that we can draw a directed graph (figure~\ref{fig:circuit1_dag})
+of the failure modes and derived components.
+Using this we can trace any top level fault back to 
 a component failure mode that could have caused it.
+In fact we can re-construct an FTA diagram from the information in this graph.
+We merely have to choose a top level event and work down using or gates.
 
+\begin{figure}[h]
+ \centering
+ \includegraphics[width=400pt]{./circuit1_dag.png}
+ % circuit1_dag.png: 797x1145 pixel, 72dpi, 28.12x40.39 cm, bb=0 0 797 1145
+ \caption{Directed Acyclic Graph of Circuit1 failure modes}
+ \label{fig:circuit1_dag}
+\end{figure}