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ArcticMyst Security by Avery

DIY Diode Driver Changes in Layout

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Oct 30, 2010
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Currently in upgrading a layout i foud here for DIY drivers and was wondering about a few changes to design and components. Let me know what you think of these. (still scaleing etching layout to get exactly the right size)

Im thinking of switching the cap to a tantalum 47uf 35v
Resistor is changed to whatever value you need

But yea im open to changes before i produce a test set of about 10-30 PCB copies.

(Please note I do not own the design to this layout i am simply redrawing for a simpler picture and opening it up for change)
 

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should work but imo that is a big cap. my drivers are all very small. and only use a 1uf cap, and they work perfectly. (you dont "need" a cap but it does help) Other than thay its good. but why do you need to make a run of board?
They can be done very well and quick on a proto board. no need to spend money on a simple lm317.
Heck i use smd parts for mine and i build all the parts small enough to fit behind and aixiz housing.
Imo a board is over kill for such a simple driver.
But yeah it looks good.
looks like you are new to making your own boards.
just a hint fill in the un used areas with black. that way you dont waste your etching acid. there is nothing wrong with leaving large areas of copper, a good idea is to try to make the extra areas a ground to help reduce noise.
 
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A 1-10uf cap is plenty. The pot will probably fail as is. They are rated for 1/4w and 5 ohms will put it over 1/3w. So......when you dial closer to 0 the load falls on the small area really straining it hard. A 100 ohm pot won't be easy to set, especially near the lower end. if you wanted 50ma out you'll already be in the lower 1/4 of the 270* arc.

The LM317 has a drop out of 2.2v and the 1117 is only 1.1v. A much better choice IMO.
Your board shows the 317 standing upright. That will be near impossible to fit in a flashlight type host. A project box build , no problem.
As far as making a PCB, I'd ask why also. Are you making kits to sell or a lot of lasers? 30ea is a lot of drivers.

It would be far easier to build it dead bug style on the face of the 317. It would also be much smaller. I just did a D Pak size 1117 I have pics of. I used a piece of PBC to hold the parts and really didnt need it. Just made it thicker. lol It is pushing 450ma on a LPC-815 diode so I had to heat sink it a little since its abt 1/2 the size of a 317 T220 case.

Just some thoughts................I'd reconsider the pot though.
 
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Yes im fairly new to prototyping but im doing this at my school so acid washing is cheap/PCB if free there is no cost on production of boards. As for this not fitting into my host its for a labbys :D yeah ill think about changing pot just dunno what to replace it with im gonna try and run it into a (LPC-815) and gonna try to get some were from 250mW-350mW more if i can (Heat Sinking isnt a problem). This is running off a Variable AC PSU so im using a larger cap to handle the spikes. After i get the through hole version to work ill switch it out and make a SMD layout.

Doing this as a project for the school so the teacher can have some Drivers for students who are aspiring to do more than simple kits he has. (Im not saying this should be for all students most are not responsible enough to handle this type of project) Also im keeping a few for myself ie mabye 5-10 (So i can do tests using different Drivers insted of part swapping)
 
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I looked hard for a 25 ohm SMD pot with no luck so far. They would work for builds 125ma out or less. 350mw is gonna need a 3.6ohm resistor, no pot. It'll put out abt .440W of heat so a 1/2W resistor will work. If its going in a project box RS has a 25 ohm wirewound.
Good luck on your project.
 
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Yeah i have all the parts you stated alread except the pot i order bulk online (Jameco Electronics) for my home collection so 25 ohm is going on the list of parts. Ill prolly use a radial pot if then since it would be anice feature but if the amperage is to high i guess ill just use a jumper on the 2 -3 lead of the pot correct? Also the RS project box its way to small for my PSU Im getting some wood shop guys to fabricate a test box but if they dont do it ill use a medium sized plastic storage bin. Aixiz Modules are 11.25mm in diameter i read, so ill get a aluminum Heat sink lathed/drilled then chop a flat section off the bottom to avoid using a stand. Just waiting for my LD to come in the mail then after i set it up ill take pics and post them in the media section providing i dont LED my diode.:(

Edit: took out stupid question
 
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Sorry, been away for a few days. I'm a new grand dad...again...lol
You mentioned using a variable AC supply? The drivers use DC voltage as do the diodes.
If thats a filtered Variac, you'll need to rectify and filter it well t use it as a supply.
AC, even at the correct voltage, could very well kill your driver and diode. Not good.
I'd be looking into some rechargeable batteries, well regulated psu(DC) or making a full wave rectifier circuit, well filtered, to put on you variable ac supply if its output is only AC voltage.

Thanks for the rep.
 




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