This guy shows a few good examples of simple layout changes to make your boards more flexible:

http://www.robotroom.com/PCB-Layout-Tips.html

They should be able to handle 2A each (the sticker on the box says it's rated up to 6A) so they probably will generate a bit of heat so you're probably right.

Interesting site about the PCB design. I'll have another look at that later .

I only started looking into PCB design last week, never made one before. Want to design an interface board for my floppy organ to make it a bit neater.

I like that page, even if it's just because everything looks really neat and tidy.

I've clicked about a bit more and it's made me want to design a PCB.

Are these things cheap to get made?

I think the answer is no from a quick search. £80-100 seems to be the figure for the size I might want.

Don't pull that out at the airport.

There's a few options for making the PCB.

You can order them from a PCB fab place, but it really doesn't make financial sense unless you're doing a fairly big run of boards. I read a while ago about a new service someone was setting up getting small batches done via China for pretty cheap (compared to normal prices, anyway). Can't remember what it was called.

Making your own: Simplest way is toner transfer to transfer the layout to a copper board, and then you chemically etch the rest of the copper off. Can be hit and miss (I've heard) with small traces - depends on your print quality/transfer quality.

An interesting alternative is to use a CNC mill to remove the unneeded copper, with precision being governed by the quality of your CNC machine.

(the other other method is to be at Uni, where they have proper PCB manufacturing kit that can do plated through-holes, multi layers, masks, type etc. )

I might get you to make me one then....!

Otherwise I saw the toner transfer one, getting the chemicals to do the job should be easy for me. Might give that a go.

Sadly I don't get direct access to it, have a friendly lecturer who's happy to get stuff done for me for my silly projects but not sure he'd be happy to extend that to "this guy in met on the Internet."...

How big so you want it? An American site doing 3 copies of a 2 layer board for $5 per square inch + $5 delivery shipping.

I was thinking 20cm x 15cm. That's probably on the big side.

That'd work out pretty expensive then. I suppose even a few inches each side wouldnt be cheap. Could you squash it into 1"x1"? ;)

Could be fun to try it. Might depend if I'm in the mood for a full body search or not.

I've just been playing with the PWM output with my LED strips. I cut off a small section to test with the Uno.

There's a library called PWM which lets you choose any frequency. I set the frequency to 2000Hz and the flicker at the lowest brightness was almost undetectable. At 20,000Hz (I didn't test anything in between) it had completely gone.

If you have problems with flicker give that a go. I'm now thinking it might be worth setting up an Arduino to control the lights as I don't really like the flicker at low brightness and it would be nice to get rid of it.

Very useful to know. I did wonder about PWM frequency.

Have you got a link to that library? I'm just using analogWrite at the moment.

Something I discovered recently (may not be of any use to you but probably handy to know). The Arduino has 6 PWM pins, controlled by 3 timers. Now obviously each *pin* can be set to a seperate duty cycle (0 - 255), but also each *timer* can be set to a separate frequency. So, if you need it for anything, you can have 3 different PWM frequencies, but each pair of pins shares that frequency. There's also some other PWM modes ( http://playground.arduino.cc/Main/TimerPWMCheatsheet ) that may be useful to know.

Makes it possible to control your LEDs with a high frequency, but also if you need to run something else lower, say a motor or something, you can do that to. Don't know if you can use that library to control it (probably, not looked) but you can control it directly from the arduino with the right commands (see link above).

I read something about the PWM timers being different where one is better to use than another. I'll try and find where I saw that.

It's this: https://code.google.com/p/arduino-pwm-frequency-library/