Light signal monitoring circuit esp. for auxiliary signals e.g. railway signalling type

摘要

The circuit includes a signal lamp (LE) which can be connected to a power supply via the contacts of two regulators in the forward and return leads of the lamp (LE). The contact or contacts (SO2/1,SO2/2) of one regulator connect the forward lead (5). The contact or contacts of (E1/1) of the second regulator connect the return lead (6) to connect the signal lamp (LE). An indicator (M) is provided in series with a dc source (B). One terminal of the indicator (M) is connected to the return lead (6) between the regulator contacts (E1/1) and the signal lamp (LE). The other terminal of the indicator is connected to a terminal (L1) of the power supply. The indicator circuit preferably has a high Ohmic value such that the current from the dc source via the lamp and the indicator is less than the glow threshold of the lamp (LE).