Why Is There Still Light After The Light Strip Is Turned Off?
Contact Name : Manda Lai；Tel : +8618026026352 (wechat/whatsapp)；Email : sale@ledtealight.com
1. Residual current in circuit design
(1) Capacitive effect: Capacitors in light strip control circuits are used for current smoothing and filtering. After the light strip is turned off, the capacitor may still have a charge and release a small current like a "capacitor", lighting up some of the lamp beads, causing the light strip to glow weakly. This phenomenon can last from a few seconds to a few minutes until the capacitor is depleted of charge.
(2)Leakage current: After the switch is turned off, the circuit may still have a trace amount of leakage current, usually due to poor line insulation or poor quality switching components. For example, damage or aging of the insulation may cause current to leak, reaching a certain amount that can light up the light strip.
(3) Inductive coupling: In complex circuits, cables close to light strips may produce small currents due to electromagnetic induction. This "invisible force" induces a current in the strip light circuit when the current in nearby cables changes. For highly sensitive LED lamp beads, these tiny currents are enough to make them emit light.
2.Characteristics of power adapter
(1)High sensitivity LED lamp beads: LED lamp beads have a low starting voltage, and some can emit light when the voltage is less than 1 volt. When the lights are turned off, even if there is a small voltage remaining in the circuit, the LED lamp beads may still light up. This shows that the lamp beads are very "sensitive" and can work with a small voltage.
(2)Power leakage: Some low-quality power adapters will still have a weak DC current output after being turned off. This is due to internal circuit design or component problems that cannot effectively isolate the power supply, causing the light strip to glow.
(3)Characteristics of switching power supply: After the electronic switching power supply is powered off, the internal circuit may temporarily retain the voltage because the energy storage components such as capacitors still maintain the voltage after the power is cut off, causing the light strip to illuminate briefly.
3. Environmental factors
(1)Static interference: Static electricity or electromagnetic interference may cause slight voltage effects on the light strip circuit. For example, in a dry environment, static electricity from the human body may be transmitted to the circuit through contact, causing the lamp beads to flicker or dim. In addition, the electromagnetic fields generated by nearby electrical appliances such as motors and transformers may also affect the light strip circuit.
(2)Wiring problem: If the positive and negative poles of the light strip wiring are not correctly connected, abnormal current backflow may occur. Normally, current flows from the positive pole to the negative pole, and incorrect wiring is similar to changing the direction of the water flow, causing the lamp beads to glow.
4.Solution
(1)Improve circuit switches
First, make sure the switch can completely cut off power. A high-quality switch can effectively block the current when turned off, preventing residual current from causing the strip to glow. Well-known brand switches have passed strict testing, have reasonable contact point design, and can accurately disconnect the circuit.
The second choice is a switch with anti-leakage function. A bipolar switch is preferred and can completely break the circuit. Compared with single-pole switches, bipolar switches cut off the live and neutral wires at the same time, reducing induced current and effectively reducing the afterglow after the light strip is turned off.
(2)Optimize the power adapter
Choose a power adapter with good voltage regulation to ensure accurate control of the output voltage and rapid reduction to prevent the lamp from starting accidentally. High-end adapters usually have complex voltage stabilizing circuits to ensure stable and accurate voltage. And ensure that the power adapter has a complete power-off function to prevent low-quality products from still outputting DC current after being turned off. A high-quality adapter will completely cut off power when turned off, preventing the strip from dimming. Refer to product specifications and user reviews to evaluate power-off performance when purchasing.
(3)Deal with residual charge in the circuit
A bleeder resistor is connected in series in the light strip circuit to quickly consume the residual charge of the capacitor and prevent the charge stored in the capacitor from causing the light strip to glow after the circuit is closed. The bleed resistor acts as a "charge consumption channel" to quickly release the charge in the capacitor when the circuit is closed, avoiding bright light caused by the capacitive effect. When selecting a bleeder resistor, circuit parameters such as capacitance size and voltage need to be considered to determine the appropriate resistance value and power.
(4)Check line connections
Make sure the light strip wiring is connected correctly and follow the positive and negative wiring rules. Incorrect wiring may cause abnormal current and affect the lighting of the lamp beads. When installing, pay attention to check the polarity markings of the light strip and power supply to ensure correct connection. Checking the quality of the ground is also critical. Good grounding prevents static electricity and electromagnetic interference from affecting the light strip circuit. Poor grounding may lead to accumulation of static electricity and weak voltage, affecting the lighting of the lamp beads. In an environment with many electrical equipment, good grounding can guide static electricity and interference current into the ground and maintain the normal operation of the circuit.
(5)Use isolation devices
Adding a relay isolation device to the control circuit can completely cut off the connection between the light strip and the power supply like a "circuit guard". When the relay is disconnected, the circuit path between the power supply and the light strip is blocked, eliminating the problem of low light. The relay controls the circuit on and off through electromagnetic force. When the coil is powered on or off, the contacts are closed or opened to achieve reliable control of the power supply of the light strip.
