| Description | Date | Identifier | |
| Wiring diagram for testing the distribution box and cutout for a 40/50 model. | 23th Jan 1931 | Box 60 \ 2 Scan028 | |
| Production specification for inspection and testing of a Phantom II medium output dynamo with a 48 coil armature. | 23th Jan 1931 | Box 60 \ 2 Scan029 | |
| Specification of inspection and test procedures for a 40/50 HP medium output dynamo with a 48 coil armature. | 22th Jan 1931 | Box 60 \ 2 Scan030 | |
| Instructions for testing a dynamo, including insulation resistance and the main bedding of brushes. | 22th Jan 1931 | Box 60 \ 2 Scan031 | |
| Test procedures for dynamo brush noise, bedding, and output observations. | 22th Jan 1931 | Box 60 \ 2 Scan032 | |
| Testing procedures for a dynamo, covering noise, vibration, brush sparking, and insulation. | 28th Jan 1931 | Box 60 \ 2 Scan033 | |
| Undesirability of control brush blackening on the Phantom II dynamo and suggesting its removal from test specifications. | 28th Jan 1931 | Box 60 \ 2 Scan034 | |
| Blackening phenomenon during the production test of a Phantom II medium output dynamo. | 28th Jan 1931 | Box 60 \ 2 Scan035 | |
| Cover letter for the running test specification of a 40/50 HP dynamo. | 11th Jun 1931 | Box 60 \ 2 Scan036 | |
| Specification for a running test of a 40/50 HP Dynamo. | 11th Jun 1931 | Box 60 \ 2 Scan037 | |
| Cover note for the production inspection and test specification of a 40/50 Dynamo Field Resistance Unit. | 5th Jun 1931 | Box 60 \ 2 Scan038 | |
| Production inspection and test procedure for a 40/50 Dynamo Field Resistance Unit. | 15th Jun 1931 | Box 60 \ 2 Scan039 | |
| Cover sheet for the Production Inspection and Test Specification for a Dynamo Field Resistance Unit. | 6th Oct 1931 | Box 60 \ 2 Scan040 | |
| Production inspection and test procedure for a 40/50 and 20/25 Dynamo Field Resistance Unit. | 16th Oct 1931 | Box 60 \ 2 Scan041 | |
| Attaching the specification of acceptance tests for the new Watford and B.T.H. Magnetos. | 24th Jul 1931 | Box 60 \ 2 Scan042 | |
| Amendment to the specification for Aero Magneto Acceptance Tests. | 3rd Aug 1931 | Box 60 \ 2 Scan043 | |
| Specification of inspection and test for a sequence starter motor with a longitudinal damper. | 20th Mar 1931 | Box 60 \ 2 Scan044 | |
| Test procedures for an armature operated switch, pinion spring, insulation, and brush bedding. | 20th Mar 1931 | Box 60 \ 2 Scan045 | |
| Test procedure document detailing light, armature return, and damping tests for a motor. | 20th Mar 1931 | Box 60 \ 2 Scan046 | |
| Blueprint wiring diagram showing the arrangement of apparatus and connections for a starter motor test. | 20th Mar 1931 | Box 60 \ 2 Scan047 | |
| Test procedure for longitudinal motion involving switches, a motor, and a flywheel with a brake drum. | 20th Mar 1931 | Box 60 \ 2 Scan048 | |
| Page from a test procedure manual detailing motor tests, specifically the Teazer Torque Test and the Load Test. | 20th Mar 1931 | Box 60 \ 2 Scan049 | |
| Test procedures for a motor, including load test specifications and a brush distress test. | 20th Mar 1931 | Box 60 \ 2 Scan050 | |
| Test procedures for a motor, including intermittent load, drop-out torque, pinion examination, and insulation breakdown. | 25th Feb 1932 | Box 60 \ 2 Scan051 | |
| Specification of production inspection and test for a sequence starter's combined main and auxiliary switch unit. | 25th Feb 1932 | Box 60 \ 2 Scan052 | |
| Inspection and setup instructions for a main switch unit, detailing clearances and contact gaps. | 25th Feb 1932 | Box 60 \ 2 Scan053 | |
| Test procedure for a switch unit, specifying current limits and contact pressure. | 25th Feb 1932 | Box 60 \ 2 Scan054 | |
| Test specifications and gap measurements for an auxiliary switch unit. | 25th Feb 1932 | Box 60 \ 2 Scan055 | |
| Test specifications for a switch, detailing current limits and voltage breakdown tests. | 25th Feb 1932 | Box 60 \ 2 Scan056 | |
| Table of measurements and tolerances for main and auxiliary switch unit gaps. | 25th Feb 1932 | Box 60 \ 2 Scan057 | |
| Covering memo for the test specification of a 40/50 Switchbox. | 5th Jun 1931 | Box 60 \ 2 Scan058 | |
| Specification of test procedures for a 40/50 switchbox. | 15th Jun 1931 | Box 60 \ 2 Scan059 | |
| Procedure for testing electrical circuits and switch functions using a 12-volt battery and lamp. | 11th May 1933 | Box 60 \ 2 Scan060 | |
| Cover letter for a revised production specification for the condenser for 20/25 and 40/50 battery ignition. | 11th May 1933 | Box 60 \ 2 Scan061 | |
| Production test procedure for a paper dielectric condenser for battery ignition. | 11th May 1933 | Box 60 \ 2 Scan062 | |
| List of testing procedures for condensers, including voltage, charge, capacity, and sparking tests. | 1st May 1941 | Box 60 \ 2 Scan063 | |
| Drawing comparing the profiles of two tested rods. | 1st May 1941 | Box 60 \ 2 Scan064 | |
| Reference note regarding a Thermionic rectifying valve for H.T. | 1st Jan 1931 | Box 60 \ 2 Scan065 | |
| The type of thermionic rectifying valve used for ball gap voltage measurement from ignition coils and magnetos. | 9th Jan 1931 | Box 60 \ 2 Scan066 | |
| Letter from M-L Magneto Synd. Ltd. concerning a B.T.H. U3 rectifying valve for a High Tension Voltmeter. | 12th Jan 1931 | Box 60 \ 2 Scan067 | |
| Request to obtain particulars on thermionic rectifying valves for H.T. rectification. | 4th Jan 1931 | Box 60 \ 2 Scan068 | |
| Letter from The Edison Swan Electric Co. Ltd. regarding an obsolete B.T.H. U.3. valve and potential alternatives. | 23th Jan 1931 | Box 60 \ 2 Scan069 | |
| Specifications for a rectifying valve for a high-tension voltmeter. | 27th Jan 1931 | Box 60 \ 2 Scan070 | |
| Letter from The Edison Swan Electric Company regarding a custom rectifying valve. | 13th Feb 1931 | Box 60 \ 2 Scan071 | |
| Specifications for a rectifying valve for H.T. for the Edison Swan Electric Co. | 7th Feb 1931 | Box 60 \ 2 Scan072 | |
| Specification document for a rectifying valve used in high tension DC insulation testing or ball gap voltage measurement. | 17th Feb 1931 | Box 60 \ 2 Scan073 | |
| Report page discussing modifications to a valve's anode diameter and filament support for a specific purpose. | 26th Feb 1931 | Box 60 \ 2 Scan074 | |
| The procurement and specifications for a H.T. rectifying valve from the Edison Swan Electric Co. | 26th Feb 1931 | Box 60 \ 2 Scan075 | |
| Inquiry to Joseph Lucas Ltd. regarding the type of high tension rectifying valve used for measuring coil voltage. | 26th Jan 1932 | Box 60 \ 2 Scan076 | |
| Letter from Joseph Lucas Limited concerning the valve used for Peak Voltage measurement. | 28th Jan 1932 | Box 60 \ 2 Scan077 | |
| Enquiry for a high tension rectifying valve. | 1st Mar 1932 | Box 60 \ 2 Scan078 | |
| Enquiry to Joseph Lucas Ltd. regarding a promised valve and the progress on equipment for the Bentley, specifically starter motors. | 10th May 1932 | Box 60 \ 2 Scan079 | |
| Letter from Joseph Lucas Limited regarding a broken valve. | 11th May 1932 | Box 60 \ 2 Scan080 | |
| Requesting approval for the purchase of a new valve for an ignition voltage measurement apparatus. | 12th May 1932 | Box 60 \ 2 Scan081 | |
| Extract of a memo discussing a misunderstanding over the design of a battery indicator. | 29th Nov 1928 | Box 60 \ 3 Scan001 | |
| Methods to prevent car accumulator over-charging, comparing the 'Midgley device' to a simpler proposed system. | 18th Feb 1927 | Box 60 \ 3 Scan002 | |
| Request for a sketch to clarify the arrangement of a battery overcharge indicating device described as a 'syphon'. | 26th Feb 1927 | Box 60 \ 3 Scan003 | |
| Extract discussing the fitting of a meter to car 7-EX, suggesting a voltmeter is a more suitable and desirable alternative. | 1st Mar 1927 | Box 60 \ 3 Scan004 | |
| Letter from accumulator manufacturer Peto & Radford discussing the design and testing of battery indicators. | 9th Mar 1927 | Box 60 \ 3 Scan005 | |
| Continuation letter providing feedback on car battery performance and comparing tungsten versus platinum points. | 9th Mar 1927 | Box 60 \ 3 Scan006 | |
| Requesting more detailed information and drawings for a charge indicator and a gassing indicator. | 30th Mar 1927 | Box 60 \ 3 Scan007 | |
| Letter to Mr. C.R.N. Minchin regarding Mr. Royce's scheme for a battery full charge indicator, complete with a diagram. | 7th Mar 1927 | Box 60 \ 3 Scan008 | |
| Query about tungsten points and a dynamo, with a pasted response regarding an expert report on cells. | 16th Oct 1918 | Box 60 \ 3 Scan009 | |
| Different schemes for a charge indicator to save the battery and dynamo. | 29th Mar 1927 | Box 60 \ 3 Scan010 | |
| Letter from Peto & Radford discussing combining a water temperature indicator with a tail lamp failure indicator. | 7th Apr 1927 | Box 60 \ 3 Scan011 | |
| Letter discussing a provisional patent for a battery gassing indicator and its operation. | 8th Apr 1927 | Box 60 \ 3 Scan012 | |
| Letter discussing the complications of a relay for a tail lamp indicator and an overcharge prevention switch. | 13th Apr 1927 | Box 60 \ 3 Scan013 | |
| Postscript to a letter anticipating the recipient's response. | 13th Apr 1927 | Box 60 \ 3 Scan014 | |
| Two circuit diagrams for a tail lamp and indicator lamp system. | 22th Apr 1927 | Box 60 \ 3 Scan015 | |
| Battery charge indicator which uses a green light to prompt the driver to adjust the ignition switch. | 22th Apr 1927 | Box 60 \ 3 Scan016 | |
| Letter to Mr. G.R.N. Minchin regarding the output of a special dynamo and an auto charge reducing switch. | 27th Apr 1927 | Box 60 \ 3 Scan017 | |
| The electrical charging system, automatic switches, indicators, and ignition components. | 25th Oct 1927 | Box 60 \ 3 Scan018 | |
| Chassis electrical system, focusing on battery size, dynamo output, and charging issues. | 25th Oct 1927 | Box 60 \ 3 Scan019 | |
| Electrical charging current levels, considering user feedback and the development of an auto-switch control system. | 12th Oct 1927 | Box 60 \ 3 Scan020 | |
| Explanation of a charging system diagram, detailing the Voltmeter, Danger lamp, and Auto switch units. | 12th Oct 1927 | Box 60 \ 3 Scan021 | |
| Continued discussion on electrical system components, focusing on the voltmeter and a proposed 'Danger Lamp Unit'. | 12th Oct 1927 | Box 60 \ 3 Scan022 | |
| Design and wiring of a four-terminal electrical unit for a dynamo-battery circuit. | 12th Oct 1927 | Box 60 \ 3 Scan023 | |
| Continued discussion on dynamo-battery system faults, danger lamp circuits, and cutout coil connections. | 8th Oct 1927 | Box 60 \ 3 Scan024 | |
| Continued discussion on electrical wiring configurations for components like the voltmeter and danger lamp. | 8th Oct 1927 | Box 60 \ 3 Scan025 | |
| Diagram of a chassis electrical system incorporating alternatively a Danger Lamp Unit or an Auto Switch Unit. | 18th Oct 1927 | Box 60 \ 3 Scan026 | |
| Design of a semi-automatic electro-magnetic switch, referred to as Mr. Royce's Green Lamp Scheme. | 22th Nov 1927 | Box 60 \ 3 Scan027 | |
| List of winding wires used on auto charge control and green lamp switches for 12 volt and 6 volt systems. | 22th Feb 1928 | Box 60 \ 3 Scan028 | |
| Concerns over fitting a new automatic charge control device and proposing simpler alternatives. | 22th Feb 1928 | Box 60 \ 3 Scan029 | |
| Instruments in auto lighting plants, with thanks to a Mr. Clark and a suggestion for an alternative scheme. | 23th Feb 1928 | Box 60 \ 3 Scan030 | |
| Temperature compensation and modifications for an electro-magnetic switch and green lamp scheme. | 23th Feb 1928 | Box 60 \ 3 Scan031 | |
| Improvements to the auto charge control switch and its application to the green lamp scheme. | 2nd Mar 1928 | Box 60 \ 3 Scan032 | |
| Proposed modification to an electrical charging system and its indicator lamp scheme. | 8th Mar 1928 | Box 60 \ 3 Scan033 | |
| Technical discussion on the green lamp charge indicator scheme and related ignition switching. | 8th Mar 1928 | Box 60 \ 3 Scan034 | |
| Request to manufacture two units of a Battery Charge Controller for the R's Green Lamp Scheme, listing new parts required. | 3rd Mar 1928 | Box 60 \ 3 Scan035 | |
| The modifications for a 'Green Lamp Scheme' on an experimental car. | 15th Mar 1928 | Box 60 \ 3 Scan036 | |
| Particulars of windings for a green lamp scheme and auto charge control switch for 12-volt systems. | 16th Mar 1928 | Box 60 \ 3 Scan037 | |
| Comparison between an auto charge control switch and a green lamp scheme for vehicle electrical systems. | 29th Mar 1928 | Box 60 \ 3 Scan038 | |
| Continued discussion on the relative merits and reliability of an auto switch versus a green lamp switch unit. | 29th Mar 1928 | Box 60 \ 3 Scan039 | |
| Comparison between a green lamp warning scheme and an auto switch for the dynamo charging system. | 30th Mar 1928 | Box 60 \ 3 Scan040 | |
| Three types of complaints with the dynamo-battery system and various proposed solutions. | 30th Mar 1928 | Box 60 \ 3 Scan041 | |
| Modifying the auto charge control system to eliminate customer complaints, detailing a proposed system for chassis 12-EX. | 30th Mar 1928 | Box 60 \ 3 Scan042 | |
| Continued list of modifications and explanations for vehicle electrical components and wiring. | 25th Oct 1927 | Box 60 \ 3 Scan043 | |
| Technical report on troubleshooting the green lamp switch and dynamo-battery circuit. | 25th Oct 1927 | Box 60 \ 3 Scan044 | |
| Technical note on temperature compensation for auto charge control switch units. | 25th Oct 1927 | Box 60 \ 3 Scan045 | |
| Technical comparison of an auto charge control switch versus a green lamp warning scheme. | 25th Oct 1927 | Box 60 \ 3 Scan046 | |
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