What is an LED driver in a sign?
The electronics between the airfield circuit and the LEDs. It takes what the isolation transformer supplies and turns it into the steady current the LED module needs to light the face.
An LED does not run directly from the airfield circuit. Between them sits the LED driver: an electronic unit inside the sign that takes the supply from the sign’s isolation transformer and gives the LED module a regulated DC current. LEDs are controlled by current, not voltage, and too much current damages them quickly, so this regulation is the driver’s main job.
The driver also protects the LEDs against surges, overheating and open or short circuits, and it is designed so that the sign’s brightness follows the brightness step of its series circuit. When a driver fails, the sign goes dark, flickers or lights unevenly, and the LED module is often undamaged but is checked too; the driver is replaced as a unit.
Electronics. Converts and regulates the power. Sits between the transformer and the module.
The LEDs and lenses that make the light. Fed by the driver, replaced as a unit.
- Supply. The series circuit feeds the sign through its isolation transformer.
- Convert. The driver changes the supply to DC for the LEDs.
- Regulate. It holds the current to the LED module steady.
- Follow the step. The sign’s brightness follows the circuit’s brightness step.
- Protect. It guards the LEDs against surges, heat and open or short circuits.
- Light. The LED module shines through the face or into the light guide plate.
Frequently Asked Questions
Q1What is an LED driver in an airfield sign?
An electronic unit inside the sign that takes power from the isolation transformer and supplies the LED module with a regulated DC current, so the LEDs light the face steadily and are not damaged.
Q2Why can’t LEDs run straight from the airfield circuit?
LEDs need a controlled DC current, and the supply from the transformer is not in that form. The driver converts and regulates it, which protects the LEDs and keeps the light steady.
Q3Does the sign still dim and brighten with the circuit?
Yes. Sign drivers are designed so the sign’s brightness follows the brightness step of its series circuit. The exact behaviour depends on the product, so check the manufacturer’s data.
Q4What happens when an LED driver fails?
The sign may go dark, flicker or light unevenly. The LED module is often undamaged, so the usual repair is to replace the driver as a unit and then confirm the sign lights evenly. A surge that damaged the driver can also damage the module, so check both.
Q5Where is the driver in the sign?
Inside the sign enclosure, wired to the isolation transformer on one side and to the LED module by a connector on the other.
Q6Is it safe to open a sign to check the driver?
Only after the circuit is isolated, locked out and proved dead under the site permit-to-work procedure, because a sign on a series circuit is live while the circuit is on, and the loop voltage can be high.
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