Hey folks,
I have a new project where i am wanting to use an Arduino uno to switch a few bits of electronics (including an LED) on/off. I have been reading everything on transistors and resistors and arduino outputs and leds and am lost in a maze of formulas for working our what resistors i will need for the transistors and LED. I would greatly appreciate it if someone with more experience could help.
1) I want to use the arduino and a 2N2222 transistor to switch a camera on/off switch. The camera will be ran off the 5v arduino pin - no info on how many mA it uses but it has a 220mA battery...
What resistor will i need for this transistor?
2) I am also going to run a 350mA 1W LED off the 5v arduino pin and want to switch it on/off hopefully with a TIP120 transistor from the arduino. What resistor will i need for this transistor? Also, i read that the 5v can supply up to 1A so 350ma LED should be fine right - will it draw the right amount of current it needs to run/ i dont really know anything about led drivers.
I have the datasheets for the transistors but they are missing some graphs from others i have seen. I worked out i would need a 185ohm for the TIP120, a 10ohm for the LED and no idea for the 2N2222. I dont know if these values are anywhere near right - i am sure it should't be this hard... On top of this i have read some people don't use resistors with transistors and it worked fine - whats going on!
Any help would be great!
Thanks
Replies