Part of a project I'm working on will be to control a set of LEDs with an Arduino. I will need to use PWM to dim them. I think the LEDs were taken from an automotive application, so they already have all the resistors or whatever built in. I just need to supply them with 12V and enough current.
Last night I hooked them up straight to a 12V battery and measured the current with a multimeter. They use about 750 milli amps.
I have sitting in my box a TIP120 transistor. (Datasheet)
On the package, I have the following specs: Power dissipation: 65W Collector-emitter voltage: 60V Collector-base voltage: 60V Emitter-base voltage: 5V Collector current (continuous): 5.0A Collector current (peak): 8.0A Base current: 120mA Unclamped inductive load energy: 50 mj
Questions about specs: Does "collector current" mean the transistor can handle up to a 5 amps load?
Does "base current" mean that the arduino needs to supply 120 mA to trigger the transistor to "flip the switch?"
How much current can an arduino supply from all its output pins? Is the 120 mA for the transistor significant? I am wondering because while the Arduino is triggering the transistor, it will be doing other things, with other current draws.
Does "Emitter-base voltage" mean that I need to put 5V on the base to get it to switch?
Questions about wiring:
To wire this up would I do this?
+12v supply -> collector Arduino PWM pin -> base + side of LED wires -> Emitter - side of LED wires -> ground
Do I need any resistors or capacitors in there? Maybe a "pulldown" resistor between the transistor base and ground, the way you do with a physical switch?
I have tried googling and looking at tutorials. Most of them only show how to do it for one circuit, and don't explain WHY, or they are way too advanced for me. Thank you for any help.