12V power supply, 8 3V led with how much resistance 12V 3A power supply, 8 3V LED lights, each 100mA, how much resistance? How to connect

12V power supply, 8 3V led with how much resistance 12V 3A power supply, 8 3V LED lights, each 100mA, how much resistance? How to connect

Four LED lights are connected in series to form a group, eight are two groups, and then the two groups are connected in parallel to 12V power supply

If a 3V LED is connected to a 12V power supply, how much resistance should be connected? Is it in series or in parallel? How many resistances should be connected (with formula)? This one can light up normally

Although LEDs all need 3V voltage, different power LEDs need different current. Generally, the maximum current of common LEDs is 20mA. Generally, the current should be controlled at 14-18ma. If it is this kind of LED, a resistor of 500-640 Ω should be connected in series. If the power of LED is 1W, about 300mA current is needed. At this time, a resistor of 32 Ω with 3W power should be connected in series, Divide the voltage shared by the resistor by the current required by the LED. Then calculate the power of the resistor: divide the square of the voltage shared by the resistor by the value of the resistor

How to calculate the resistance of a 12V led
Can you tell me the specific algorithm?

The on voltage of red and green LED is about 2V, and that of white LED is about 3.3V
If the working current is 10mA, then:
The red and green tubes are connected with resistance of 1K Ω, and the white light tubes are connected with resistance of 870 Ω (the actual series resistance is 810 Ω)

I want to connect 12 LED lamps to 12V power supply. Are the three lamps connected in series and then connected in series with resistors and connected in 4 series, or are the three lamps connected in series with 4 series in parallel and then connected in series with resistors
Lamp voltage is 3V, current is 20mA, how to series resistance?

The resistance of the lamp can be calculated to be 150 ohm
In the first method, the three lamps should be divided into 3V, so the resistor should also be divided into 3V, so as long as each series branch is connected with a 150ohm resistor. At this time, the power consumption of the four resistors is 0.02 * 15 * 4 = 1.2W
In the second method, the equivalent resistance is 450 / 4 = 112.5 Ω after three series and four parallels. If the voltage is still divided into 9V, the series resistance should be 112.5 / 3 = 37.5 Ω, which is OK. At this time, the electric power consumed by a resistor is 0.02 * 4 * 37.5 = 3W
Compare the first plan first