High Brightness Uv Led

A powerful black light can be achieved with UV LED and a simple electronic Assembly. LEDs are connected in series and fed by a power capacititve without transformer.

Black light led

Diagram of LED UV black light

The LEDs are powered directly on the sector, without transformer:

Diagram of LED UV black light

The capacitive power (to capa chutrice) sets the current using the value of C1 and C2 in parallel (total C = C1 + C2 = 1.68uF). The diode bridge straightens the tension and C3 smooth resulting voltage of the diode bridge. The LEDs are connected in series, you can put about 10 to 25.

The nominal voltage of C3 must be greater than the threshold voltage multiplied by the number of LEDs.

Example: 20 LED 3.4V serial: 20×3.4 = 68V. You must choose a 100V capacitor.

The F1 fuse protects feeding in case of short circuit in the diode bridge. If one or even all of the LEDs the LEDs are in short circuit, there is no danger to the power supply. Indeed, the current is limited by C1 + C2 and reaches dangerous values. In fact, the short circuit current is barely higher than the rated current (100mA).

The theory on food capacititve, understanding and calculations:

LED series and false contact: danger for LED

The only danger of this Assembly is a bad contact in the LED. Imagine the current is interrupted in the LED after a false contact. The voltage at the terminals of C3 will go up gradually, possibly exceeding the rated voltage of C3. Moving on… In fact, the tension will cap around 1.2 to 1.5 x the rated voltage of the capacitor due to the large leakage current which will appear (analogy with the zener diode). But mostly when the contact will recover, the LEDs will be powered by a good voltage too high and a current peak will cross them. This current peak corresponds to the brutal shock of C3 up to his “normal” blood pressure. For example, from 120V to 68V. This can destroy or damage all LED a coup. However, a loose connection elsewhere does not jeopardize the LED life. Here at LEDLightsClassified.com you can get more different models of the lightings.

Therefore, power must never operate without the LED.

Production practice of UV LED black light

First, present an overview of the black light:

Black light led

The black light is mounted on a support in hand plated of 15x15cm.

Capacitive power of black light led

Capacitive power of black light led (zoom on the DF10S bridge)

Zoom on a capacitor X 2

C1 and C2 must be of class X 2 (250V ~) because they support the mains. You may use templates 630VDC if there is no class X 2. Should never use capacitors 250VDC.

The LEDs are mounted in series on a map of bakelite scraped to the grinder. The “tracks” help widely (not negligible with 85mA…) heat dissipation. In operation, the tracks heat at 50 °.

LED black light (side view)

LED black light (almost front view)

LED black light (front view, never look!)

LED black light seen from the front

These LEDs emit at 405nm (intense violet). They contain 5 chips well visible on photos above it. These 5 chips in parallel allows a current of 100mA (5x20mA).

The brightness of the LEDs may seem altogether low because the purple is little perceived by the eye.

Rendering of black light led

The beam is very powerful, the opening angle is 40 °, which concentrates the light unlike the classic black light (tubes of 60 cm or 1.20 m).

Rendering of the black light on different materials

Rendering of the black light on fluorescent materials

Beware the eyes: never look directly at the UV LED!

We see a neon yellow pencil, a LED 20W white hot (pink fluorescence) and a LED cold white 20W (less visible white fluorescence). Lit by black light LEDs are tested in detail in this article:

Conclusion on the black light

Black light led is a compact and modern achievement that can replace the old (and expensive) classic hits. The focusing of light offers an efficient and targeted, ideal light intensity to illuminate an area or a group of person for evenings and moods…