Controlling an LED video light with Arduino

Hi Everybody,

I want to control a LED light normally used for photography with an Arduino.
The light is similar to this one:
http://dx.com/p/aputure-amaran-al-160-13w-5600k-1200lm-160-led-video-light-black-139708
It runs on 6 1.5v batteries, but I plan to take one out and wire the contacts to a transistor controlled by Arduino.

My questions are:

  1. Would a transistor such as the bc547 be suitable to control this light with 7.5v and around 50ma?
  2. Is there any danger to the arduino, and should I use one (or more) diodes somewhere along the circuit?

Thanks!
Eran.

vertigo5:
My questions are:

  1. Would a transistor such as the bc547 be suitable to control this light with 7.5v and around 50ma?

Where did you get the "50mA" figure from?

13 W @ 7.5V is nearly 2 amps. You'll need a MOSFET to switch that.

Get a TO220-package, N-channel MOSFET with "logic level" in the description. Be sure to use a heatsink.

vertigo5:
2. Is there any danger to the arduino, and should I use one (or more) diodes somewhere along the circuit?

No danger but be sure to put a resistor between the Arduino pin and the MOSFET gate. 220 ohms should be fine.

PS: Don't try to dim it using PWM. It looks like that won't work.

I got the 50ma using my multimeter to connect the two battery contacts with the other five 1.5v batteries inside, the light went on and the multimeter read 50ma. Is that right or am I missing something?

Would this MOSFET do the job?
http://www.vishay.com/docs/91017/91017.pdf

Thanks!!!
Eran.

vertigo5:
I got the 50ma using my multimeter to connect the two battery contacts with the other five 1.5v batteries inside, the light went on and the multimeter read 50ma. Is that right or am I missing something?

I don't know where the error is but it can't possibly be right. It has to be a lot more than that

160LEDs at 20mA each adds up to about 12W ... 7.5V at 50mA is only a third of a Watt.

vertigo5:
Would this MOSFET do the job?
http://www.vishay.com/docs/91017/91017.pdf

Nope. That's not logic level so the Arduino won't be able to fully open it.

You need one with an 'L' in the name, eg. IRL540 (if you like Vishay)

Thanks!
I will get the IRL540 and try the circuit out.
Will also try to recheck my measurements and see where I got it wrong.