Hi all, can someone tell me if I was to run LED's off 9 volts what size resistor would I need to use.
Best regards Dave.
I put together a dome light in my truck(40ultra bright super flux leds). I just made my circuit and used two 1watt 100ohm resistors..Its not the proper way to do it , but it can be done.
so it is possible to use 1 resistor light up the whole works.. I would stress that you bread board that circuit first ,more so if your leds are not all the same. its is possible to blow leds doing what I did.
Chances are , 3.2v and 20ma are general led power requirements ,On 9 volt
http://led.linear1.org/led.wizSolution 0: 2 x 4 array, 1 extra LED
+----|>|----|>|---/\/\/----+ R = 150 ohms
+----|>|----|>|---/\/\/----+ R = 150 ohms
+----|>|----|>|---/\/\/----+ R = 150 ohms
+----|>|----|>|---/\/\/----+ R = 150 ohms
+----|>|----------/\/\/----+ R = 330 ohms
The wizard says: In solution 0:
each 150 ohm resistor dissipates 60 mW
the wizard says the color code for 150 is brown green brown
the wizard thinks ¼W resistors are fine for your application
the 330 ohm resistor dissipates 132 mW
the wizard says the color code for 330 is orange orange brown
the wizard thinks ¼W resistors are fine for your application
together, all resistors dissipate 372 mW
together, the diodes dissipate 576 mW
total power dissipated by the array is 948 mW
the array draws current of 100 mA from the source.
Solution 1: 1 x 9 array uses 9 LEDs exactly
+----|>|---/\/\/----+ R = 330 ohms
+----|>|---/\/\/----+ R = 330 ohms
+----|>|---/\/\/----+ R = 330 ohms
+----|>|---/\/\/----+ R = 330 ohms
+----|>|---/\/\/----+ R = 330 ohms
+----|>|---/\/\/----+ R = 330 ohms
+----|>|---/\/\/----+ R = 330 ohms
+----|>|---/\/\/----+ R = 330 ohms
+----|>|---/\/\/----+ R = 330 ohms
The wizard says: In solution 1:
each 330 ohm resistor dissipates 132 mW
the wizard says the color code for 330 is orange orange brown
the wizard thinks ¼W resistors are fine for your application
together, all resistors dissipate 1188 mW
together, the diodes dissipate 576 mW
total power dissipated by the array is 1764 mW
the array draws current of 180 mA from the source.