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ArcticMyst Security by Avery

DIY Laser Torch

H

hydro

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Feb 20, 2008
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I need some help please. Just got most of the parts to build this bad boy but what I want is to use 2 cr123s 3.6V (7.2v total) with about 420mA at 3 volts output. I know if I use a 3 ohm resistor it should give me 416mA but the with 7.2v input it will give me 4.2v output right? Now here is where I'm stuck, I can't find a 3 ohms resistor so what combinations can I use to give me that 3 ohms range? All the resistors I can find are 33, 20, 15 and 10 ohms (1/2 watt). With what I have I know I can get 2.5 ohms but this will give me 500mA and that is too high. Also how can I bring down the 4.2 volts to 3 volts? Do I add a pot, if so what size or can I add 2 1N400X in series between the V-out (LM313T) and the 3 omhs resistor? Please keept in mind that space is very limited and with a heat-sink there is really no space at all. Thanks for the help inadvance. :-/ :( :-[
 





jayrob

jayrob

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hydro said:
I need some help please.  Just got most of  the parts to build this bad boy but what I want is to use 2 cr123s 3.6V (7.2v total) with about 420mA at 3 volts output.  I know if I use a 3 ohm resistor it should give me 416mA but the with 7.2v input  it will give me 4.2v output right?   Now here is where I'm stuck, I can't find a 3 ohms resistor so what combinations can I use to give me that 3 ohms range?  All the resistors I can find are 33, 20, 15 and 10 ohms (1/2 watt). With what I have I know I can get 2.5 ohms but this will give me 500mA and that is too high.  Also how can I bring down the 4.2 volts to 3 volts?  Do I add a pot, if so what size or can I add 2 1N400X in series between the V-out (LM313T) and the 3 omhs resistor?  Please keept in mind that space is very limited and with a heat-sink there is really no space at all.  Thanks for the help inadvance. :-/ :( :-[
Click to expand...

Your voltage will be right using 2 X 3.6 volt RCR123 rechargeable batteries. The LD will need 3ish and the driver will use over 3 as well. We have been using just a single resistor, no pot for the MXDL at this power. If your going to use this MXDL that DDL has shown here, and you are talking about a 3 ohm resistor, I'm sure you are going to use an open can diode. You may want to pick up one of my heatsinks. If you want the heatsink, just remind me, and I will give you a 3 ohm resistor with it. Also, the stock MXDL has a resistor. It usualy is a 3 ohm resistor. You will have to check the color markings, and compare here: http://samengstrom.com/nxl/3660/4_band_resistor_color_code_page.en.html If you are interested in the heatsink, check here: http://www.laserpointerforums.com/forums/YaBB.pl?num=1202452073/0 Have fun with your build!...
Jay
 
H

hydro

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Hey Jay that looks great, wish I was not short on cash right now. Any way I'm still waiting on parts from aixiz, can't proceed with project without the blank housing. Any one have problem with order being shipped in a timely manner? It has been 22 DAYS from the time I order and paid for the parts.
 
I

Ifrgtmyname

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Feb 24, 2008
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Call me a bit of a noob here but why would batteries be such a big problem, after all u do have a capacitor. Also the batteries are meant to chuck out 3V each right?

So if the battery is sending out 3.1V how much harm would it do?- What is the watershed?
 
jayrob

jayrob

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Ifrgtmyname said:
Call me a bit of a noob here but why would batteries be such a big problem, after all u do have a capacitor. Also the batteries are meant to chuck out 3V each right?

So if the battery is sending out 3.1V how much harm would it do?- What is the watershed?
Click to expand...

Depending on the driver/LD combination. I know about the LM317 based drivers. (DDL) There are other drivers. The DDL driver is very poplular. The red diodes draw about 3 volts. The blu-rays draw 4.5 to 5 volts. The DDL driver needs over 3 volts total. So, depending on what LD you are trying to drive, and what driver you want to use, you must have the proper battery supply voltage...
Jay
 
B

bcroft

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Dec 28, 2007
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i been paying attention to mA and not the battery voltage. im using DDLs driver, plan on using a phazor LD from the GB and just ordered some batteries that the volts are supposed to be 3.0 to 3.2 under load but charge up to 3.6. is 3.6 too much for my setup? how do find out if it is?
 
jayrob

jayrob

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bcroft said:
i been paying attention to mA and not the battery voltage.  im using DDLs driver, plan on using a phazor LD from the GB and just ordered some batteries that the volts are supposed to be 3.0 to 3.2 under load but charge up to 3.6.  is 3.6 too much for my setup?   how do find out if it is?
Click to expand...

For the DDL (LM317 based) driver, and a Phazor (red) dioed, you want at least 2 X 3.6 volt batteries. The driver can handle up to 37 volts input. But for driving these red diodes, the 3.6 rechargeable batteries X 2, are just right...
Jay
 
Z

zanthrax

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Mar 3, 2008
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I have a LM317 transitor, but unlike yours its larger and has a metal piece with a circular hole cut into it, what exactly is the difference and can I use it in this project? Thanks!
 
jayrob

jayrob

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zanthrax said:
I have a LM317 transitor, but unlike yours its larger and has a metal piece with a circular hole cut into it, what exactly is the difference and can I use it in this project? Thanks!
Click to expand...

I use the same LM317 that you are talking about. Take a look at the pictures and notes in my 'Driver Tips' document. You have to cut the metal piece down some to make room. Also, be aware that this metal part of the LM317, is VOut (as well as the middle pin). So, do not let it touch anything...
Jay
http://www.sonic.net/~jayrob/MXDLDriverTips.doc
 
S

steelybob

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Feb 26, 2008
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got my heatsink from jayrob and merideth unit in the last couple of days. i have all my components to make the driver if my damn mxdl will ever get here from china. anyway here are some pics of what i have so far... god i hope i haven't fried anything yet lol.

steelybob

meredith glass unit installed
 

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  • meredith_1.jpg
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jayrob

jayrob

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steelybob, that's looking really clean! Just a note to others about the Meredith, if you haven't used one before, (I think that you and I already discussed this) but from your pictures, you can see that the focussing knob/ring is not screwed in all the way. The Meredith modules, can be a little 'tricky' to get to the proper focus. Especially the glass lens ones. Take a look at my notes/tips on the Meredith modules here in my 'Heatsink Tips' document...
Jay
http://www.sonic.net/~jayrob/MXDLHeatsinkTips.doc

P.S. I have some other useful information on the DDL style driver here:
http://www.sonic.net/~jayrob/MXDLDriverTips.doc

I have sometimes even had to go a step further to get focus with the Meredith glass lens. Take a close look at this picture. The outer 'skirt' of this brass piece, (where the spring is connected) has been cut shorter. This is to allow more room inside the module case for focussing.
Meredith mod.jpg
 
S

steelybob

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Feb 26, 2008
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jayrob thank you again for all your help. after i took those pics i did take the LD back out and filed about .030 off of the face of the brass adapter. i guess i will have to see once i get everything together if i need to file some of the skirt off... we'll see.
 
Abray

Abray

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Nov 18, 2007
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Ok I've already fried one diode in this project and have absolutely no idea why. When I checked the current, it either read 1,200 mA or 300 mA or 600 mA, depending on how it was feeling (meaning I have no idea). I had checked and double checked my circuit, and still got an LED. Now I am working on trying to actually make a driver for this so when my two new drives arrive, I can actually NOT fry them! I think my curcuit is ok, even though it seems it only works when it wants to. I just have a problem with the circuit board found within the MXDL. It won't stay put in that metal piece, and this really messes with the battery configuration. Also, where exactly do I need a wire leading back to the negative terminal of the battery? I can't seem to figure this out, and I think this may be a problem too.

I'm not exactly a "noob", but I am having ALOT of trouble with this project. any help?
 
jayrob

jayrob

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Abray said:
Ok I've already fried one diode in this project and have absolutely no idea why. When I checked the current, it either read 1,200 mA or 300 mA or 600 mA, depending on how it was feeling (meaning I have no idea). I had checked and double checked my circuit, and still got an LED. Now I am working on trying to actually make a driver for this so when my two new drives arrive, I can actually NOT fry them! I think my curcuit is ok, even though it seems it only works when it wants to. I just have a problem with the circuit board found within the MXDL. It won't stay put in that metal piece, and this really messes with the battery configuration. Also, where exactly do I need a wire leading back to the negative terminal of the battery? I can't seem to figure this out, and I think this may be a problem too.

I'm not exactly a "noob", but I am having ALOT of trouble with this project. any help?
Click to expand...

Abray, this 'Driver Tips' page should help you to see how the ground is connected. The MXDL tail switch, is what connects the body of the MXDL to the negative side of the batteries. So you have to connect the negative side of your driver, to the MXDL case...
Jay
http://www.sonic.net/~jayrob/MXDLDriverTips.doc
 
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