01-10-2019, 12:43 PM
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.