Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

Mod - 15-20 mW 635nm keychain

Joined
Jul 8, 2007
Messages
530
Points
0
NOTE - I started this project earlier this week before SMIDSY's post.. just so you don't think I'm ripping him off..

Pumped up red keychain pointer

Brief: Modded a ~$5.00, 5mW red keychain pointer. Replaced diode with 15-20 mW 635nm (sdl7501) + apc power supply (ns102) + Meredith acrylic lens. :)

Here a picture of it (middle) compared to LED flashlight (left) and lighter (right):
keychain.jpg


If you live in the US, these pointers can be found at Target, in the pet section. Not bad for a $5.00 pointer! (or, here: http://www.thepuppyshop.com/laserchase.html) During my first violet pointer build I ripped apart one of my 'homemade' 635nm flashlight laser pointers (more, here: http://www.candlepowerforums.com/vb/showthread.php?t=140955) to get at the Meredith housing and optics. In the process I shattered the diode window on my beloved 635nm diode. This diode has lasted for years.

After picking the shards of glass out of the window, I was happy to see the diode still lased. I decided to attempt to resurrect this diode, this time in a truly pocketable package.

Below you can see can exploded view of the 'laser chase' pointer. After working on this thing I must say it's something of a masterpiece of simplicity and economy. All brass construction. The switch assembly includes a resistor + an 'open can' diode chip directly mounted to the PCB. If you're using well behaved batteries, like alkaline or silver oxide, a resistor is really all the power supply you need. It also sports a focusable lens. Pointer runs off three 'LR44' button cells. I recommend the Energizer 357 high drain equivalent. Beneath the pointer switch you can see what I'm replacing it with - the 9mm SDL diode, socket and the tiny ns102 APC supply.

keymod_1.jpg


Here's a closeup of the pointer switch + PCB, beneath it you can see its replacement the 9mm sdl7501, and the weee little ns102 power supply, just a few mm's per side. I have nothing but good things to say about the ns102 - it's an APC supply, meaning it uses the third PD pin on the diode to keep the optical output constant, adjusting the current as needed. It works with an input voltage range of 2.5-9 volts, and also has a slow start. This diode+power supply has lasted me many years, 100's of hours of use and has taken a lot of punishment. It works well in all temperature extremes, I've tested it from 0 (F) to over 90 (F).

keymod_2.jpg


I started the mod by separating the PCB from the brass housing. I then sawed off a bit of the back of the brass housing and glued the 9mm diode can to it. The 9mm diode can has a large metal lip, and its diameter was just a little less than the brass pointer assembly, so I was able to get it centered well. Next I cut down the PCB and ripped the resistor off it. I then glued the ns102 to the end of the PCB, and soldered the diode legs directly to it.

As luck would have it this assembly fit back into the pointer casing, and it worked!!! However tragedy struck just a few hours after completion. The pointer abruptly stopped working. The autopsy revealed why: repeatedly pushing the button had ripped the diode legs off the ns102 supply, as well as pulling the traces off the PCB. AAAAUUUGH!!! I spent a couple days sulking. I had flunked the mechanical part of the design, and needed a new approach. The switch had to be braced better.

I came up with a new plan. I decoupled the switch&power supply from the diode. I then did reconstructive surgergy on the ns102. I nearly went blind and berserk soldering wires to something about the size of a housefly's butt. Sometimes I had to solder the wires to the traces leading to where the solder pads had been on the PCB. Eventually I was successful. The idea was to glue the switch into place first, and then solder the wires to the diode and push that into place.

In the pics below you can see the pointer switch, with the NS102 glued to the end of it. Both sides of the ns102 are used - the side with the smd ic is glued, the other side has the trim pot and a few smd parts. Q-tips were employed as structural elements, and the switch was glued and braced into place about the botton, with the wires sticking out the front of the pointer. A royal PITA. Next the the diode assembly was soldered, and then pushed into place.

Pics before this happened

keymod_3.jpg


keymod_4.jpg



This was not fun. I had chosen too heavy a guage of wire, and during the press fit of the diode assembly into the pointer I was worried I'd rip the soldered wires off the NS102, or the diode. Since the ns102 was glued into place I would have been f*cked if this happened. Of the four wires, three are four the diode, the fourth is the '+' connection, squeezed between the case and the brass flange.

Anyway, it worked!! The switch is now well braced and functional.

Next, lens choice. In the image below you can see the three lenses at my disposal - from left to right, Meredith glass (shimmed with electrical tape), Meredith acrylic, and the plastic lens that came with the pointer. The Meredith acrylic worked, and that's what's in there!

keymod_5.jpg


The head of the pointer is a little cockeyed. The + wire squeezed between the pointer case and housing was too fat. I decided to leave it this way, rather than risk ripping any wires out by pusing it all the way in.

So, I'm happy with it. This pointer is about as bright as a 50-60 mW DVD diode (~655nm) would be. Fairly gory! My 125mW red burning laser appears no more than twice as bright.

I'm using 357 batteries.. the current draw of the diode is 80-90mA, so I doubt I'll get more than 1/2 hour of continuous use.. more than enough for the little pointer however. My old boss will sell me these batteries for $1.00/each, a better price than the $2-3 each at the drug store.

Below is an honest beam shot in a smokeless room with the shades drawn.

keymod_6.jpg


And the pointer.

keymod_7.jpg
 
Last edited:





Joined
Jul 8, 2007
Messages
530
Points
0
I got the ns102 years ago at <alltronics.com>. They were around $15.00/pop. I don't think they have them anymore.

Digikey has a few flavors of this supply. Here, for example:http://parts.digikey.com/1/parts/690507-power-supply-laser-smt-ns102-200k.html

It's a good supply for any red laser, up to 100-125 mA. APC. I did have some trouble with the trim pot being touchy, once set it's a rock solid supply. It's survived several resolders (and very high heat) and has protected the diode flawlessly for years.

{EDIT} Here's more info on the ns102 - these people want $30.00 for the part, which I think is a bit much:
http://www.nvginc.com/ns102dri.htm
 

VW

0
Joined
Mar 1, 2008
Messages
577
Points
0
Yeah, deffinately a cool little laser, nice...
 

SMIDSY

0
Joined
Mar 7, 2008
Messages
881
Points
0
flogged said:
NOTE - I started this project earlier this week before SMIDSY's post.. just so you don't think I'm ripping him off..

I dont think anyone believes you would rip me off ;D

I like your project its more complicated than mine...

do you have any more of those pumped up assemblies? Im looking to make a second more powerful laser ;)
 
Joined
Jul 8, 2007
Messages
530
Points
0
No more complete assemblies. I DO have more of these 9mm 15mW 635nm diodes however. The 9mm can is a bit easier to work with than the 5mm package. I don't have anymore of the ns102 power supplies. I'd be willing to part with a couple of these diodes for $5-10 each if you wanted to attempt to make a lil 15mW 635nm pointer.

I meant to ask if there'd be any interest from the populous as far as purchasing these. I'm planning on making another 2-4 of these, and then selling them for $25-30 each. They will be true 15mW 635nm keychain pointers. The only difference would be I'd just use a resistor for the power supply (no ns102 - it adds too much to the cost) and the plastic lens that comes with the pointer.
 

caleb

0
Joined
Nov 27, 2007
Messages
321
Points
0
im realy wanting those 15mw diodes. if anybody knows where i can get them for cheap, PM me, thanks dudes.
 
Joined
Oct 26, 2007
Messages
5,438
Points
83
There are always some 635nm diodes for sale on eBay. I got 10 for like $30. They're rated 7mW, but you can push them quite a bit further.
 




Top