viii
4
Applications
Figure 4-1
Leakage current measurement ..................................................................................................................... 4-2
Figure 4-2
Diode characterization ................................................................................................................................. 4-3
Figure 4-3
Diode curves ................................................................................................................................................ 4-4
Figure 4-4
Capacitor leakage tests ................................................................................................................................ 4-4
Figure 4-5
Capacitor measurement ............................................................................................................................... 4-5
Figure 4-6
Insulation resistance measurement (unguarded).......................................................................................... 4-6
Figure 4-7
Insulation resistance measurement (guarded).............................................................................................. 4-7
Figure 4-8
Insulation resistance measurement using external voltage source .............................................................. 4-8
Figure 4-9
Measuring high-impedance gate-source voltage ......................................................................................... 4-9
Figure 4-10
Configuration for voltage coefficient studies ............................................................................................ 4-10
Figure 4-11
Faraday cup construction ........................................................................................................................... 4-11
5
Performance Verification
Figure 5-1
Connections for amps and coulombs verification ....................................................................................... 5-3
Figure 5-2
Connections for volts verification ............................................................................................................... 5-4
Figure 5-3
Connections for ohms verification............................................................................................................... 5-5
Figure 5-4
Connections for input impedance verification............................................................................................. 5-6
6
Theory of Operation
Figure 6-1
Overall block diagram ................................................................................................................................. 6-2
Figure 6-2
Basic configuration of electrometer preamplifier........................................................................................ 6-2
Figure 6-3
Electrometer preamplifier configuration ..................................................................................................... 6-3
Figure 6-4
Simplified schematic of input stage............................................................................................................. 6-4
Figure 6-5
Gain stage .................................................................................................................................................... 6-4
Figure 6-6
Output stage configuration in volts and ohms ............................................................................................. 6-4
Figure 6-7
Output stage configuration in amps and coulombs...................................................................................... 6-5
Figure 6-8
Ohms voltage source simplified schematic ................................................................................................. 6-5
Figure 6-9
Zero check configuration in volts and ohms................................................................................................ 6-6
Figure 6-10
Zero check configuration in amps and coulombs ........................................................................................ 6-6
Figure 6-11
Simplified schematic of ranging amplifier .................................................................................................. 6-6
Figure 6-12
Multiplexer and buffer ................................................................................................................................. 6-7
Figure 6-13
Multiplexer phases....................................................................................................................................... 6-7
Figure 6-14
-2V reference source.................................................................................................................................... 6-7
Figure 6-15
A/D converter .............................................................................................................................................. 6-8
7
Maintenance
Figure 7-1
Calibration jumper location ......................................................................................................................... 7-3
Figure 7-2
Input offset and current adjustment locations.............................................................................................. 7-4
Figure 7-3
Connections for Model 6512 calibration ..................................................................................................... 7-5
Figure 7-4
Connections for external voltage source...................................................................................................... 7-6
Figure 7-5
Exploded view ........................................................................................................................................... 7-10
A
IEEE-488 Bus Overview
Figure A-1
IEEE-488 bus configuration ....................................................................................................................... A-1
Figure A-2
IEEE-488 handshake sequence................................................................................................................... A-3
Figure A-3
Command groups........................................................................................................................................ A-6
Summary of Contents for 6512
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