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 worked out i would need a 10ohm for the LED
On top of this, i have read on the net that some people don't use resistors with transistors and it worked fine - whats going on!
Thanks fungus! Cleared up a few things.I ran a formula and worked out i should use a 2.5k ohm resistor for the TIP120 running a 1W LED. Does this sound in the ballpark?
Bit wary of running a led straight off the power supply - so i saw some cheap 1w led drivers on ebay. They run on 12v. Do you think i could switch one of these with another resistor and an external power supply?
It doesn't have an operating voltage, i was just going to run it at 5v originally from the arduino 5v pin?
This is my LED: http://www.ebay.com.au/itm/1W-Infrared-IR-940NM-High-Power-LED-Bead-Emitter-with-20mm-Star-Base-/221063642644?pt=LH_DefaultDomain_0&hash=item33786b7e14&_uhb=1#ht_4040wt_1163
I used this calculator to calculate resistor values for transistors:http://kaizerpowerelectronics.dk/calculators/transistor-base-resistor-calculator/I thought forward voltage was not operating voltage - just the volts that drops once it's through the LED? I could run a 22.214.171.124v drop led on 5v no?
On another note I could use 50x 5mm LEDs like these:Forward Voltage (V) : 1.2-1.4V.Forward Current (mA): 100mA.
Once again they have 1.2-1.4 forward voltage - could I run them from 5v? If so would the Arduino have enough milliamps to run 50 of them in series and what resistor should I have? Looks to me like they would use 5A.