Smiths bi-metal type electronic temperature and fuel level gauges require a voltage regulator which provides a stabilised voltage within a close tolerance to ensure gauge accuracy.
The regulators have 4 lucar terminals.
The female Lucars marked "I" connect to the gauge
The male lucars marked "B" connect to the power feed.
The regulators must be mounted in the orientation as indicated by the "Top" arrow.
The regulators are available for either positive or negative earth systems.