DIY Laser Torch

Yup, you're right, black green black gold gives you a 5ohm resistor with a 5% tolerance.
If you're going to drive your LD at 250mA you're going to need a 1/2 watt resistor. When using the LM317 you calculate the wattage of the resistor needed by multiplying the current by the LM317's reference voltage. i.e if you want to know the wattage of the resistor you need to drive your diode at 250mA you multiply the reference voltage (1.25) by the current (.250) which equals .3125 watts, so you need to use at least a 1/2 watt resistor to run your laser diode.

And of course a 20x diode is better, a SenKat diode running at 250mA will output between 150 - 180mW, but when running a 20x diode at 420mA and using a glass lens you can get an output between 280 to over 300mW.

Alright, so I've been lookin for the best deals in capacitors and found these with a relativly low shipping price (less than 2 bucks). The first one I know will work, but the seccond one holds my quesion, it seems smaller and has a higher temp value, so wouldnt it be better? (easier to fit in the flashlight if so)
ww.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=020-1152&scqty=10
ww.partsexpress.com/pe/showdetl.cfm?&Partnumber=020-1744

just add another "w" to the hyperlinks, said I couldnt post links

Daedal said:

For our purposes, we now have a circuit that we can do whatever we want with it, and place whatever we want on it, already made to fit this flashlight! So I grabbed one of my smaller LM317 chips and two 10-ohm resistors. The resistors are from the RadioShack bundle pack. I wound the resistor terminals onto each other from both ends to make one 5-ohm resistor rated up to a half an amp. I soldered that in place between the Adj and the Vout terminals of the LM317, and then I soldered the POSITIVE LD wire to the Adj line. Yes, the same place where the resistors attach to, you can just use the same piece of solder.

MAKE SURE YOUR SOLDER IS CLEAN. MAKE SURE THE TERMINALS ON THE LM317 ARE NOT SOLDERED TOGETHER. MAKE SURE NOTHING IS GROUNDED INSIDE THE CASE.

From here, I connected the LM317 Vin wire to the junction on the circuit that corresponds to the positive terminal. Then I connected the ground wire to the ground. I connected the ground wire to a spot on the circuit board that connects to the designated positive terminal on there. It’s the one that connects to the outside ring on the bottom.

Click to expand...

Ok so it may be a stupid question but this is my first laser and I am still trying to learn about them. To me, having never built a laser or worked with parts like this before, this may as well be in a different language :-? . What is this really doing for the laser and is it really necessary? If so would you be willing to help me through this step. I would love to use this guide but I am unsure of this particular segment. Thanks.

The LM317 regulates current, is no mystery, and very easy to work with. The following calculations always apply since it uses 1.25 volts for its reference voltage.

To calculate the resistor needed for a given current, take 1.25 and divide it by the current. So say you want to drive a SenKat diode with 250 ma's. 1.25 divided by .250 = a 5 ohm resistor.

Another way you could do this is to take 1.25 and divide it by the resistance. 1.25 divided by 5 = .250.

Next you will want to calculate the wattage of the resister needed. We know 1/2 watt resistors are common for use with the regulator. But to figure it out, simply take the 1.25 and multiply it times the current. 1.25 times .250 =.3125 watts.

The rule of thumb for the voltage going into the regulator is it should be 3 volts more than the voltage going to the diode. A SenKat diode running at 250ma's will have about 3 volts across it. Therefore a minimum if 6 volts is needed.
I recommend 6 nimh batteries or 2 RCR123's for use with Daedal's driver.

What he is talking about is a driver to power the laser diode. You can't just connect a laser diode straight up to the batteries because it will DIE.
Here's the thread on how to build the driver.
And here's a video tutorial.

zanthrax said:

JayRob- what resistor do you use, I like how you have it single...? or do you have a link to share, it would help me a lot, thx! (I'm using LDs from StoneTek, supposed 20x and come with an Axiz module) I'm readin through this thread now, just hopen for a faster more precise response... dont want to waste a bunch when i buy in bulk.

Click to expand...

Sorry, I had missed this question. I like to use a 3 ohm resistor. But remember that this is because of the use of an open can diode that can handle the 420mA's. Also the use of a nice thick heatsink. I just posted a list of all of the parts and links in a different thread, but it wouldn't hurt to post it here as well:

If you want to build a nice red burner, I will give you information on my build.
http://www.laserpointerforums.com/forums/YaBB.pl?num=1204144556

Here is a list of everything you will need. Take time to read the threads that I have linked here. This is a very good build. It is a 'pumped up' version of Daedal's original 'DIY Laser Torch'. Daedal is commonly referred to as DDL.

I sell the completed lasers. But not the parts to the lasers.

As far a individual parts, the only thing I sell is the heatsink. $23 dollars plus shipping. To the U.S., the shipping is $3 bucks. PayPal: jayrob@inreach.com

I make heatsinks for only two MXDL models. Check this thread:
http://www.laserpointerforums.com/forums/YaBB.pl?num=1202452073/0

I can give you links to where you can buy the other parts for the build:
Host: http://www.dealextreme.com/details.dx/sku.4171 (red build)
Open can diode drive to harvest: http://www.newegg.com/Product/Product.aspx?Item=N82E16827118003
Another good open can diode drive: http://www.newegg.com/Product/Product.aspx?Item=N82E16827129018
AixiZ module: http://stonetek.org/shop/index.php?main_page=product_info&cPath=66&products_id=191
Meredith Module and 5.6mm adapter: http://www.mi-lasers.com/cgi-bin/shopper.cgi?search=action&keywords=diode_optics
Batteries: http://www.dealextreme.com/details.dx/sku.8683
Charger: http://www.dealextreme.com/details.dx/sku.936
Driver parts:
LM317: http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=LM317TNS-ND
3 ohm resistor: http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=003-3 *(I am including a free 3 ohm resistor with every heatsink)
Silicon diode: http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=1N4001DICT-ND
Capacitor: http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=478-1911-ND

Daedal has a very good guide on the building of this host here: (the thread we are in now)
http://www.laserpointerforums.com/forums/YaBB.pl?num=1186966870

My build is just an ‘upgrade’ of Daedal’s original build.
The differences are:
The open can diode, the heatsink, and the use of the 3 ohm resistor, instead of 2 x 10 ohm resistors and a pot. No pot, and just the 3 ohm resistor at the LM317 will give you the 420mA's. (about 250mW’s with an acrylic lens – 300mW’s with a Meredith glass lens) Heatsink needed! His thread doesn't mention the silicon diode and cap, but he shows pictures of those components in his build.

I have a couple of documents and ‘tips’ on doing this build using my custom heatsink. In my ‘Driver Tips’ document, you will find a good schematic of the original DDL driver.
http://www.sonic.net/~jayrob/MXDLDriverTips.doc
http://www.sonic.net/~jayrob/MXDLHeatsinkTips.doc
Jay

O no, I made my laser about 2 weeks ago, been having fun with it no probs. All the sudden today the laser is very dim. Do you think it's broken? or is this most likely a part I used for the driver? Personally i think its broken, but its odd to me that it turns on at all, and why it just suddenly happend. I'm using 3.7 rechargables (that were kinda cheap) and I'm wondering if that is the problem that caused this disaster I guess i'll buy another LD, least I have everything else built already...

There is still a slight chance that it is a battery failure! I have had a brand new 3.6 volt lithium work for a few seconds, and then not. I think there was a problem with the protection circuit built into the battery. Anyway, make sure you check the batteries and the driver before you give up on the LD...
Jay

Tried a different set of batteries, still very dim... i'll save try the diode in another driver another day. Is this common or no? i just dont understand how it got dim instead of completely dissappearing... perhaps it was the cheapo batteries?

anyway it was fun for the time i had it, and it'll only be 20 bucks to buy a sony diode from stonetek. btw why is that guy sencat labled as ex-member everywhere, did he get in trouble or somethin?

I'm making 5 more, parts already on the way and driver circuits already made, just hope this doesnt happen to my friends/customers... good thing i'm only chargin them $65 lol...

zanthrax said:

Tried a different set of batteries, still very dim... i'll save try the diode in another driver another day. Is this common or no? i just dont understand how it got dim instead of completely dissappearing... perhaps it was the cheapo batteries?

anyway it was fun for the time i had it, and it'll only be 20 bucks to buy a sony diode from stonetek. btw why is that guy sencat labled as ex-member everywhere, did he get in trouble or somethin?

Click to expand...

Sometimes they just get dim, other times they don't light at all. What diode did you have in your build? And what driver/current?
Jay

Oh....Senkat diode. What driver/current?

No Senkat left but is back now, i think you might have your regulator set up wrong that has happened to me, Can you take a picture?

I used the basic driver described on here with a lm317, 2 10 ohm resistors in paralell, silicone diode and really the only diff were my resistors were fireproff and my capacitor supported up to 35v. (no pot)

I dont have a good enough camera, sorry, to get a good enough shot... what do you mean exactly?
obtw it did work perfectly for 2 weeks or so, no overheating and i've charged the batts twice now... its funny because it broke in the hands of a friend- but i was watchin and he didnt do anything wrong.

I know that the earlier batch of the Sony/Senkat diodes were very good at 250mA's. Which is what, according to your description, your driver should be putting out. There was a batch of weaker diodes that I read about. I understand that now the diodes are even better than the earlier ones. But I have not tried them yet. I still have about 3 of the earlier ones. One of which, I am running at 294mA's. This is using a nice thick heatsink though.

Sorry about your LD. That is, if it is in fact the LD. Sounds like it is...
Jay

Anyway heres my complete circuit, complete with exact pictures of the parts i used, found them on live search... batteries are the only thing not the same. everything is hotglued/taped off that should be (heatsink was dremeled off)...

Hey I was about to buy another LD when i noticed stonetek's site says very boldly
Attention
The SONY DIODES have changed from SLD1239JL to SLD1239JL-54

is this good or bad lol?

oops, nvm...
http://www.laserpointerforums.com/forums/YaBB.pl?num=1206895447

Just bought 6 of them... this Senkat is simply awesome... and so is this forum. I shall work to 1000 posts and learn more about lasers lol! (cant wait for 4th of july... never had fireworks and lasers!)

Oh it's good. ;D

EDIT: About your driver pic, the silicon diode is supposed to go before the capacitor. Otherwise, if you connect the batteries backwards the capacitor will blow up. ;D