The earth grounded of LED
According to new standing and request of GB7000.1/IEC60598D:
Class Ⅰ led production must be earth grounded. Strict security measures are in force in the Class Ⅰ led production.
The Class Ⅱ led production don’t need to earth grounded.
they are double insulated and approved to international safety standards.

The earth grounded of Class Ⅱ led production can’t to earth grounded.because it belong to safe ultra low voltage (SELV)

Undesirable consequences flow from Class Ⅰ led production is not value earth grounded. This has done incalculable damage, include triggle Electrostatic Induction (caused damage to led module ), electric leakage (there is a risk of electric shock).

How to value earth grounded? Please refer to pic as follows:

With some methods, current is introduced into the earth by grounded lengths of wire

Very simple, versatile modular design
No limits to the number of modules used in the ring Circuit diagram using LEDs:Circuit diagram using Lamps:

Parts:

R1 R3 R5 10K 1/4W Resistor
R2 R4 R6 470ohm 1/4W Resistor
C1 C2 C3 47uF 25V Electrolytic Capacitor
Q1 Q2 Q3 9013 NPN Transistor
Nine pcs led 20mA 3V

The purpose of this circuit was to create a ring in which LEDs or Lamps illuminate sequentially. Its main feature is a high versatility: you can build a loop containing any number of LEDs or Lamps, as each illuminating device has its own small circuit. The diagrams show three-stage circuits for simplicity: you can add an three number of stages (shown in dashed boxes NOTE: Series Multi-level will can’t work), provided the last stage output was returned to the first stage input, as shown.

Good term between PWM and inductance to adjust led
Analog adjust led refer to adjust led luminous intensity by changing resistance .advantage: operation simply . shortcomings:The level of adjust luminous intensity is limited. In order obtain to more effect level of adjust light. We adopt inductance and PWM to adjust light. The theory as follows:

PWM through changing duty cycle to control that the conduct time of LED. The PWM can adjust multi-level led light. And inductance is energy storage component . in electrical circuit, inductance can product magnetic field when input current into inductance. The energy will release in PWM is Closure period It can not only become asset current for LED. but we need to make sure that the cycle of pwm is small than conduct time of inductance.

The relations between led current and light intensity

The LED can be produced without light For the under led forward voltage.

To Input forward voltage for LED, it will be produced light.

In an ideal status, they have the proportional relationship. But bright of led increase and temperature also increase . along with temperature increase and might damage led .

Led light theory: led light refer to Transition of electrons from the high-energy state to a low-energy state . then release by Photons(Photons have no mass — they are weightless).

The led will be light When input voltage is big than forward voltage. On the contrary the led can be produced without light.

When the voltage is big that forward voltage, the electronics quantity in high-energy state, that means current. So the current are increasing the photons will increase. But the transition rate(Quantum effects) not even be 100% . portion of current can be transition of temperature . the question of temperature could not resolve in a timely manner, it can be damage led chip. So led continuous increasing current or it not only causes led damage(base on Quantum effects).

What did The aging text box of Ultraviolet rays for?

The container is invisible until you shine an ultraviolet light on it. it’s role as follows:
Some substances are put in long hour shines by sun. they will toggle some question such as: fade, lose luster, cracked . the theory of The aging text box of Ultraviolet rays is : use uv led strip to simulate sun and use condensate water and spurted water to simulate rain and dew. Other word  with the most true of natural environment to test substance or production. Through test to analyze
that the ability of resisting oxidation and intensity . this way for improvement in performance of production. in general we gain damage information for a few years in natural environment .but It only takes a few day or a few week.

How to Measure the conduction voltage of led ?
You can Measure the conduction voltage of led with multimeter, the step as follws;
First we wanted a adjust power, and it’s series connect with resistance and LED. In here we adopt a smaller on resistance(such as 1 Ohm).now we can Measure the conduction voltage of led .two ends(NOTE: measure the voltage of led no include resistance ) . the follow we began very slowly to increase the input voltage of adjust power(the input voltage from 0 ( zero) up to) . the led luminous rapidly increased when the voltage of adjust power was gradually increase. Another phenomenon that occurs is the voltage of multimeter increase grows slowly. At moment, please take notes that voltage of LED. The record is conduction voltage of LED.

The relate between encapsulation and light effect of LED

The scaffolding led adopt ethoxyline resin to package. The method has limitations as led encapsulation condition. Their defect Were mainly represented: power small 、luminous flux small、bright lacks. It just only utilization in special LED light equipment . along with the rapid development of LED. The request of LED luminous flux is on the increase. The high power led has come into led marketplace.
The scaffolding led truly entered light marketplace to respected currently light product. There are has some problem need to solve . the led effect is most import question. In currently light marketplace, 50lm/W was the most highly luminous flux effect. The parameter of luminous has not reached the currently standard of household lighting .for short the gaps with household lighting.. the scaffolding led light effect improves should start with many facets. Such as: construction design. Materials technology and Technological process.

Flicker-free LED power
In currently ,the Flicker-free led device is popular product . especial Is led power. everybody know that normal power and Flicker-free power are extremely similar. The follow parameter will tell some different between the normal power and Flicker-free power.
*Protect measures: Flicker-free power has prefect protect measures, theirHas output over current limitation ,protect of over heated ,protect of over voltage and protect of battery polarity reversed .*Quiescent current: Tiny quiescent current when flicker-free enter sleep mode .in general is about 1mA .*Signal output:The flicker-free power adopt MCU to control power-on and power-off. The flicker-free power will be power off when Over heating or battery voltage is low.
*Output voltage: in general the designer will be adopt high accuracy power(coefficients can reached to ±0.5～±1%) *Encapsulation size: The flicker-free power adopt SOT-23 IC inside. So their shell are small that normal power.

Adjust the incandescent light
We know that Through the silicon controlled rectifier(SCF)can adjust the incandescent light and shade degree.but there are has some question is values for our design work.
*In order achieve this goal, check the phase angle of input power is necessary ,we can confirm that conducting time of SCF when the Zero crossing circuit is check out. But that’s quite difficult to do in practice, Because the noise interference will trigger conducting status is poor .error trigger to generate the current oscillation.
* Whole AC voltage almost load into LC filter of LED power on SCF conducting state. At moment , if adjust current is low that SCF maintain current ,the SCF stopped conducting.
* From datasheet, The maintain current of SCF between 8mA ~ 75mA.the incandescent work current is far more than maintain currnet,the work current will support SCF.

LED protector —- zener diode
The IC module does not protect circuit (please see pic 1 as follows).

pic 1
In application , the led will most probably be damage by high voltage moment.It was a question which deserved serious consideration. We have put a zener diode between the input voltage and ground . the “D2” zener diode function as protect LED. The theory showing as follows ：
the operation voltage is big than LED operation voltage. Anything ruing ok when input voltage in normal scale. The zener diode is work when input moment voltage is high than the work voltage of series LED. For the result ,whole voltage Put into Zener diode. When all goes well, the LED working normally again.