A method and an electronic circuit are disclosed. The method includes detecting at least one operating parameter in an electronic circuit that includes a monitored LED string; adjusting a voltage threshold based on the at least one detected operating parameter; detecting a string voltage across the monitored LED string; comparing the string voltage with the voltage threshold; and detecting a defect in the LED string based on the comparing.

A method and an electronic circuit are disclosed. The method includes detecting at least one operating parameter in an electronic circuit that includes a monitored LED string; adjusting a voltage threshold based on the at least one detected operating parameter; detecting a string voltage across the monitored LED string; comparing the string voltage with the voltage threshold; and detecting a defect in the LED string based on the comparing.

The subject disclosure relates to power failure simulations, for example to test lighting systems, such as emergency lighting units or lighted signage. In some aspects, a method of the disclosed technology includes steps for receiving an interrupt command, terminating power delivery from a first power supply to a lighting array in response to the interrupt command, and measuring one or more power characteristics of the second power supply. Methods and machine-readable media are also provided.

A chained flashlight system includes: plural flashlights; plural lighting control devices that control lighting of the plural flashlights, respectively; a communication wire; and a traffic control device. The plural lighting control devices include receiving units, controlling units, activating units, and power supply units, respectively and are coupled to the traffic control device by the communication wire. The traffic control device simultaneously sends an activating signal to the plural lighting control devices via the communication wire. The receiving units receive the activating signal. The controlling units activate the activating units based on a time from reception of the activating signal to activation of the activating units, set for the flashlights, respectively. When the power supply units are turned ON in an activated state of the activating units, respectively, the flashlights are lit by a lighting signal from the traffic control device, respectively.

A lighting device circuit comprising: a reference LED string, a mirror LED string coupled in parallel to the reference LED string, an operational amplifier based current mirror circuit coupled to the reference LED string and to the mirror LED string, and a window comparator circuit that includes only a single input that is coupled to a fault sense node. The fault sense node directly connects to a drain node of a transistor within the operational amplifier based current mirror and a LED within the mirror LED string.

A lighting device circuit comprising: a reference LED string, a mirror LED string coupled in parallel to the reference LED string, an operational amplifier based current mirror circuit coupled to the reference LED string and to the mirror LED string, and a window comparator circuit that includes only a single input that is coupled to a fault sense node. The fault sense node directly connects to a drain node of a transistor within the operational amplifier based current mirror and a LED within the mirror LED string.

Installation for powering and controlling a plurality of signalling lights (1), arranged in series, each comprising at least one light source (L1,L2), the installation comprising at least:a unit (100) for remotely programming/managing the operation of the installation, with a primary power supply (110) situated upstream (M);a primary series circuit (110) for powering the lights, with a transformer (200) for each light (1), the transformers being connected in series with the primary power supply (110);a control module (300) for each light (1), arranged between a respective transformer (200) and the associated light (1);a secondary power supply circuit (140) for powering the control modules (300), independent of the primary circuit (110) for powering the lights (1);a first optical cable (131a) for bidirectionally connecting the first upstream module (300) of the series to the programming/management unit (100);a second optical cable (132a) for bidirectionally connecting the last downstream control module (300n) of the series to the programming/management unit (100);each control module (300) being connected in series to the adjacent upstream module and to the adjacent downstream module by means of a respective bidirectional optical connection.

A lighting device circuit comprising: a reference LED string, a mirror LED string coupled in parallel to the reference LED string, an operational amplifier based current mirror circuit coupled to the reference LED string and to the mirror LED string, and a window comparator circuit that includes only a single input that is coupled to a fault sense node. The fault sense node directly connects to a drain node of a transistor within the operational amplifier based current mirror and a LED within the mirror LED string.

A lighting device circuit comprising: a reference LED string, a mirror LED string coupled in parallel to the reference LED string, an operational amplifier based current mirror circuit coupled to the reference LED string and to the mirror LED string, and a window comparator circuit that includes only a single input that is coupled to a fault sense node. The fault sense node directly connects to a drain node of a transistor within the operational amplifier based current mirror and a LED within the mirror LED string.

Provided is a light source apparatus including semiconductor light sources and a current detection resistor connected in series, a power source circuit that allows current to flow thereto, a current detection circuit that detects current flowing to the current detection resistor and outputs a current detection signal, a control circuit that controls the power source circuit such that a voltage of the current detection signal approaches a target value, a bypass circuit connected in parallel to the semiconductor light sources, and including a clamp element having a clamp voltage higher than a maximum voltage during operation of the semiconductor light sources and a bypass resistor connected in series to the clamp element, and allowing current to flow when an open fault occurs in the semiconductor light sources, and detection circuits that respectively detect an open fault in the semiconductor light sources based on an end-to-end voltage of the bypass resistors.