Ruby ignition light

[Bob Culver]

I vaguely recall someone providing an explanation for the seemingly odd choice of bulb and complicating resistor. Anyone remember the reason? Presumably with some components the cutout can be confused.

[bob46320]

This site explains a lot about the charging system (But doesn't answer your question Bob). My RN has a resistance wire wrapped around the socket of the ignition light, afraid I can't elaborate any more on that though!

http://www.austin7.org/Technical%20Artic...refresher/

[Tiger]

Thanks for the comments
However making the side connection to the bulb is my question.
Tim

[Bill Dixon]

In the 1930s Lucas used a 2.5volt bulb 0.2amp, the current rating is the important part.On 12volt cars the bulb was of the same rating,but the resistance wire wound around the bulb holder was of a higher resistance.As far as I can tell 6 or 12volt bulbs of the right current rating were not available.When the dynamo is not charging the lamp is in series with the dynamo resistance plus the resistance of the wire around the lamp holder.ehen the cut out points close this shorts the lamp out together with its series resistance.