X-Git-Url: https://git.ucc.asn.au/?p=matches%2Fhonours.git;a=blobdiff_plain;f=thesis%2Fappendices%2Felectron_gun_circuit.tex;h=d529b987544bb2404dd3caced0e28a3af6fb460d;hp=5ab7b1d26a5cf51bc382f023af79154a1d5ebdca;hb=5545f4fe8caf6b12a140ebf9c33ed0b1755b1750;hpb=543d79fb85d5f04b9364945f51c692d049e3249d

diff --git a/thesis/appendices/electron_gun_circuit.tex b/thesis/appendices/electron_gun_circuit.tex
index 5ab7b1d2..d529b987 100644
--- a/thesis/appendices/electron_gun_circuit.tex
+++ b/thesis/appendices/electron_gun_circuit.tex
@@ -1,5 +1,5 @@
 
-\chapter*{Electron Gun Control Circuit}
+\chapter*{Appendix - Electron Gun Control Circuit}
 
 The control circuit diagram for the electron gun is shown in Figure \ref{electron_gun.pdf}. The wiring of the circuit, including resistors and potentiometers, was incoroprated into a single box, with external connections available for the power supplies, ammeters, electron gun, and sample holder. Both the components and operation of this circuit are straightforward; we will give a brief overview here for completeness.
 
@@ -40,8 +40,14 @@ The control circuit diagram for the electron gun is shown in Figure \ref{electro
 \end{itemize}
 \begin{landscape}
 \begin{center}
-	\includegraphics[scale=0.80]{/home/sam/Documents/University/honours/thesis/figures/electron_gun.pdf}
+	\includegraphics[scale=0.80]{figures/egun/electron_gun.pdf}
 	\captionof{figure}{Circuit Diagram for Electron Gun Control}
 	\label{electron_gun.pdf}
 \end{center}
+
+\subsection{The Ammeters}
+
+An ideal ammeter has no input resistance. In reality, it is not the current that is measured, but the voltage accross a fixed input resistor. This voltage can either be amplified, or the resistance increased, for measuring a smaller current.
+
+The 602 and 610B electrometers both provide a large range of scales and amplifier settings for current measurement. Using a low scale setting increases the input impedance, which increases the potential drop accross the ammeter. However, using a large amplifier gain increases noise; hence there is a trade off. For the 602 and 610B electrometers, a significant drift (typical +5\% of scale in 10min) in the zero level was also observed at high amplifier gains, whilst low gains appeared more stable (+10\% noted after 2 days).
 \end{landscape}