Urgent Help Required

I want to use a laser with Arduino Uno R3 . Actually I want the laser to blink .The specifications of the laser are DC Operating Voltage (Typical):5VDC ,DC Operating Voltage (Typical) 250mA.

Can I directly connect laser to the digital pin ?

Please do help because its very urgent.[/color][/glow]
Thank you

Not at 250mA, no you can't connect it direct. You would need a transistor to act as a switch, with the i/o pin on the transistor base.

No, you can’t directly connect, that is too much current.
You can put an N-channel MOSFET between laser - and Gnd and control that with an arduino pin. Look at AOI516 at digikey.com as a good choice:
http://www.digikey.com/product-search/en?lang=en&site=us&KeyWords=aoi516
N-channel MOSFET, logic level, low Rds, low input gate capacitance, thru hole for easy mounting, low cost.
Use a 220 or 250 ohm resistor between arduino pin and the MOSFET gate, and a 10K from the gate to Gnd to keep the MOSFET off when the arduino is being reset or the pin is set to an input.

And btw I was assuming you have a laser pointer with 2 wires, which has some circuitry hidden inside, not a 3 wire laser diode which afaik needs more magic to fire it up.

A Power FET like THIS: See the datasheet etc. on that page.

DISCLAIMER: Mentioned stuff from my own shop...

Digikey is fast.. I can ship the one shown above today Priority Mail from Vermont USA... Email me if you need that.

"Be careful where you point that thing", as John Wayne used to say...

HomeWork Panic Zone??

Yes , it is a two wire laser . I am using arduino uno . Can I connect laser to drain and also an external power source to the drain while keeping source at ground and the arduino pin connected to gate with 1K resistor.
I have attatched an image please check if the connections shown are correct or not.
Thank you

images.jpg

You have drawn an NPN, that would work fine. For N-channel MOSFET, you need a Logic Level part for gate to turn full on with 5V from Arduino. IRF540 is not a logic level part except at very low current levels, like 0.25mA. For 250mA, it needs 10V to turn full on.

So what should the circuit be? I have edited the image which I mentioned in the previous comment. Please do check the modified image and see if any other changes are required ? Please tell the changes required.
Thank you

Modified image.jpg

Get a better MOSFET, such as AOI516: http://www.digikey.com/product-search/en?vendor=0&keywords=aoi516

IRF530 is no better than IRF540 http://www.irf.com/product-info/datasheets/data/irf530npbf.pdf

Thank you everyone. Now I the problem is rectified and I was able to blink the laser with the help of IRF 530. I would especially like to thank ' Cross Roads' . Sir your contribution was really helpful.

Kavish:
I would especially like to thank ’ Cross Roads’ . Sir your contribution was really helpful.

Thank him more by buying a copy of his book 8) (If you’re a teenager, also maybe even if you’re not)