Joined: Aug 2017 Posts: 934 Threads: 22
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Location: Near Cambridge, UK
Car type: 1928 tourer (mag type), short chassis Gould Ulster
Please can someone advise the resistance value of the wire wound resistor used for ignition lights. I assume that this would be the same on the SM5 round switch panel as it is on the later ignition lamp fitted to late RNs onward. I have previously shorted the resistor position and used a 12v mes instrument lighting lamp (lowest wattage I could find), which is very satisfactory, but I want to advise a purist.
Robert Leigh
Joined: Aug 2017 Posts: 178 Threads: 1
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On my RP I used a 27ohm 0.6watt resistor , the lamp is a 2.5 volt 0.2 amp on a 6 volt system. the current rating is important. This should work on the RN switch panel. This mod has worked for me since 1971. If using 12 volt system try a 47 ohm resistor. As far as I can tell Lucas used the 2.5 0.2 lamp as no 6volt or 12 volt lamps were made in the 1930s.of the correct current rating.