Hi. I am using a Motorola BC547 transistor to control a series of LEDs from a microcontroller. I bought if from futurlec, and the datasheet can be found here :http://www.futurlec.com/Transistors/BC547.shtml
The problem I have is calculating what current I have to supply the base to make my LEDs work. I want to use as little current as possible to save power. I will connect the base to a 5V IO-pin and controll the current with a resistor.
I read through the datasheet, but did not understand how to calculate the base current. Does anyone know how to calculate this? The current running through the LEDs, when active, is about 30mA.
Also, do you know anything about how much current/voltage you can run through a normal flat ribbon cable? I wonder if i can use this for my LEDs.