The input voltage is 12V. How much current limiting resistance is needed for parallel connection of two groups of circuits with four light-emitting diodes in series? How to calculate Led 3.3.6v 20mA

The input voltage is 12V. How much current limiting resistance is needed for parallel connection of two groups of circuits with four light-emitting diodes in series? How to calculate Led 3.3.6v 20mA

Enough withstand voltage, no current limiting resistor

·The voltage is 12V, a total of 500, each 3V, each current is 20mA, how to series, how to calculate the resistance, how to calculate the resistance power, thank you
·The voltage is 12V, the voltage is 50W, a total of 500 bright LEDs, each 3V, each current is 20mA, do light plate, how to series, how to calculate resistance, how to calculate resistance power, thank you

Only one group of two or one group of three can be connected in series, and then the appropriate current limiting resistor can be connected in series (so that the current passing through is 20mA). Then the two "groups" can be connected in parallel
Series resistance of a group of two branches = (12-6) / 20mA = 300 Ω
Series resistance of a group of three branches = (12-9) / 20mA = 150 Ω
Resistance power: 1 / 8 or 1 / 4 watt

What is the resistance color ring of 1m

The numbers represented by colors are: Black 0; Brown 1; red 2; Orange 3; yellow 4; green 5; Blue 6; purple 7; gray 8; white 9. The last ring of resistance represents precision, silver: 10%; gold: 5%; Brown: 1% resistance. The penultimate ring represents the last number of 0. 1m resistance, 1000000 ohm (1) "10" + 5 "0", that is: Brown (1) black (...)