Vehicle indicator lamp monitoring circuit - has warning lamp controlled by relay surrounded by coil windings opposing magnetic flux of permanent magnet beside relay

摘要

The warning lamp monitoring circuit indicates the failure of one of two indicator lamps (4, 5). The system uses a warning lamp (20) mounted on a relay housing (21) which has three terminals (8, 9, 10) projecting from its end. One side of the warning bulb (1) is connected to the earth terminal (10) and the other side (3) is connected through a reed relay (11) to the middle terminal (9) which is connected to the power supply switch (6) for the lamps. Across this middle terminal and the third terminal (8) which is also connected to the lamps, is a coil (12) with its windings around the relay. The magnetic flux from the windings oppose the magnetic flux of a permanent magnet (13) alongside the relay.