|
Secure Site Shop with Confidence Best viewed using: Internet Explorer or Mozilla Firefox |
Choosing a power source for the N8102 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. © 2008 Ngineering |