Tuesday, 20 September 2011

Farnell Stuff Review

So I was stumbling around on the internet in a semi-drunken state one Wednesday afternoon (as you do when visiting your sister's pub..) and I discovered I had an email from a nice chap at Farnell asking me to review some stuff for him. My initial thoughts were the result of a head on collision between "it's a phishing attempt/spam" and "FREE STUFF!"
fast-forward a week or two and I now have in my possession some 3 watt LEDs some AA battery holders and some ATMega328s.

Starting with the LEDs, I basically went for the best brightness to price ratio while not being SMT. I chose amber because I have plans for a future project involving these.

Fluff not included. From LEDs

The first thing I noticed about these was that they don't come with a mounting kit, so I had to place another order for the nuts and washers. Moral of this story: first time round you will always forget something.
Once everything else arrived I decided to throw together a quick test, so I threw together the first LED assembly
From LEDs
and set the hotglue gun to 11:
From LEDs
If there was an award for ugly bodges, I'd need a bigger house for all the display cabinets...

*maths time*
That's 4x 46Ω resistors giving 11.5Ω. 
The batteries are about 4.8V, minus the forward voltage of the LEDs (2.3V) gives us 2.5V
2.5V divided by 11.5Ω = ~217mA
The LEDs can take up to 750mA continuous and thus be significantly brighter, but my brain wasn't working when I put the test together.

Here's a picture of the test that followed:
Indicator Vs LED From LEDs
No points for guessing what the final project will involve :P
Once I get a microcontroller involved I'll try driving one at 1amp (the absolute maximum for 10ms pulses) though I don't think 4AA batteries will last long at that.

All in all these LEDs are pretty awesome and will definitely do the job for my upcoming emergency hazard light project

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