A question about this laser driver.

I have a question about this laser driver: http://www.laserpointerforums.com/forums/YaBB.pl?num=1185701612
I am going to build this driver so that I can make my own burner laser into a torch host that I have.

I have read somewhere that you really need to connect a dummy load to this driver in order to test it.
Is this really nessesary?

I have a digital multimeter that reads, amongst other things, current. Wouldn't it be fine to just connect my meter to the output, then measure the current, whilst adjusting the pot, until I get the correct current needed for my laser diode?

Thank you.

Yes the dummy is necessary, to tell the correct mA at the correct voltage of the laser.
this thread explains more: http://www.laserpointerforums.com/forums/YaBB.pl?num=1197651171
If you don't use the load the mA will not show right, and the voltage is weird too.

The  following rant is not directed at mike666 per se but I am seeing the "do I need to use a test load" question again and again..... three threads today so far.

I would put forward the following arguments....

YES!
It is good practice to use a test load to be sure that your newly built circuit is doing exactly what you expect.

If for some reason it is doing the wrong things you have not endangered the most expensive and hard to get part of the whole build, the LD.

The test load will have taken you 2 minutes to build and cost you about $0.50 and it will be on your bench ready for all future builds.

NO!
You don't need to use a test load as you are absolutely sure that your circuit is going to work perfect;y first time and that the output mv is perfectly matched to your LD.

You have loads of spare LD's anyway so you can afford to get it wrong and blow a few.

Your time is so precious that the 10 minutes required for testing is worth  more than an LD.

Rant over

Regards rog8811

OK thanks guys.

Sorry rog811, didn't realise this had been asked a few times today already  lol.

However I will ask this.
The curcuit diagram has a ideal voltage of 7.2v.
If I used two AA baterries, combined voltage of 3v, would that still work?

No. You must have at least 7.2v in to get the proper voltage out.

ElektroFreak said:

No. You must have at least 7.2v in to get the proper voltage out.

Click to expand...

I see.
In that case, is there a driver that works on 3v that I can build?
The host I want to use uses two AA batteries, which are 1.5v each.

In the UK I don't know of any battery that is the size of an AA but that is 3.6v instead of 1.5v.

I'm sure there is, but I don't know which one. I really only have lab modules personally, so I'm a little out of touch with pointers. The only one I can think of that might work would be a rkcstr driver. You can find info on these all over the forum, so a quick search might yield the info you seek..

Try a pair of 14500's from DX.

Above mentioned batteries here
http://www.dealextreme.com/details.dx/sku.974

Dont forget to get a charger at the same time.

Regards rog8811

[edit]just realised that those are AAA size but the AA size ones are on there somewhere [/edit]
[edit]here in fact http://www.dealextreme.com/details.dx/sku.975[/edit]

You guys are the best.    

I found the charger for those batteries but of course it is set to USA voltage.

I doubt the chargers we have in the UK, that are designed to charge 1.5v batteries, would work.

I bought a charger from DX and it autoranged from 110v to 220v so it should be there.

Loads of UK builders use these batteries as they are cheap and only 2 weeks away.....

Regards rog8811

[edit]2 minutes searching on DX got this  http://www.dealextreme.com/details.dx/sku.973
All you need to do is change the plug[/edit]