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Choosing a power source for the N8102 & N8105 LED Power Distribution Boards
N8012 LED Power Distribution Board
Remember that when LEDs are in series, you add the device voltages together and the power supply needs to provide at least that much voltage. Side-A of the board uses current sources so resistors are not required to protect the LEDs. However, the current sources take about 5 volts from the supply for power leaving the remainder for the LED series to use. For example, if a 12-volt power supply is used, each group on side-A will have 7 volts at its disposal for calculation purposes. This means that if you want to have white (3.3-volt) LEDs in a series group, you will be limited to 2 LEDs in the group (or a total of 8 on side-A). If on the other hand you want red LEDs in the series group (1.85-2 volt), you could have 3 LEDs in the group. Now, all of this is based on a 12-volt supply. With a 18-volt DC supply, the number of LEDs in a white LED group could be 4, filling up all available spots.
Side-B requires all LEDs have resistors selected based on what supply voltage will be used.
Side-B will also support connection of filament type incandescent bulbs. Be sure that the appropriate resistor is chosen based on the bulbs current and voltage specifications.
Here’s a quick rule of thumb: With a 9-volt power source, a single board will support 4 white LEDs on side A and 12 on side B for a total of 16. A 12-volt supply raises the total to 20 and an 18-volt supply would raise it to 28.
As you might expect, we carry 12-volt and 18-volt power supplies. These are highly-regulated precision switching power supplies that are small but very powerful, and are quite inexpensive. They can be found below our Distribution Board on the Lighting Accessories page.
Finally, remember to watch your resistor calculations carefully for side-B as they relate to your DC voltage source. The higher the DC source voltage, the greater the Power (wattage) size your resistors need to be. Always select resistors that exceed the calculated milliwatt usage. A link to our calculators page can be found here.
N8015 LED Power Distribution Jr.
Just like its bigger brother above, the N8105 has a current source side (top, where current source chip is mounted) and a side that requires resistors for connected LEDs (bottom side of board, shows the N8105 part number).
The current source side is configured for up to 4 series-wired LEDs and the same rules and calculations apply that are shown for the N8102 above. For example, if a 12-volt power supply is used, the current source side will have 7 volts at its disposal for calculation purposes. This means that if you want to have white (3.3-volt) LEDs in a series group, you will be limited to 2 LEDs in the group. If on the other hand you want red LEDs in the series group (1.85-2 volt), you could have 3 LEDs in the group. Now, all of this is based on a 12-volt supply. With a 18-volt DC supply, the number of LEDs in a white LED group could be 4, filling up all available spots.
The bottom side will allow for up to 4 LEDs connected either as a series group, individual LED with the own resistors (parallel configuration), or a combination of series and parallel LEDs. This provides maximum flexibility to support most wiring schemes.
The bottom side will also support connection of filament type incandescent bulbs. Be sure that the appropriate resistor is chosen based on the bulbs current and voltage specifications.
Finally, remember to watch your resistor calculations carefully as they relate to your DC voltage source. The higher the DC source voltage, the greater the Power (wattage) size your resistors need to be. Always select resistors that exceed the calculated milliwatt usage. A link to our calculators page can be found here.
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