Minimag Flashlight Laser

[photongeek]

Hi Guys:
I'm new to the forum but have been "playing" with lasers since the "OLDEN DAYS" of HeNe's. I still have my Metrologic lab laser which still works despite the fact that I've had it for over 20 years. The caps are getting a little leaky so it takes a while to warm up but it still is pretty cool.
I've seen the short Minimag vid many times and would very much like to make one of these considering the high costs of a production retail model. I have read here to start below 3 volts to determine the diode's working voltage and that is a logical approach. Is it necessary to have a driver board to stabilize the voltage for these things? What would you expect the life span of the diode to be without one? Your help is appreciated!

 

[AJ_Dual]

I'm learning as I go too.

However, the consensus seems to be that direct drive of the diode will severely limit the life, and so will a lack of heat sinking.

Current/milliamps is also very important to diode life too.

One of the "easy ways" out is to use an LED flashlight that already has driver circuitry in it. The mini-Mag mods we've all seen the videos of might not last very long, and won't have a very long duty-cycle either.

To that end, I'm using a Dorcy Jr. 1 Watt LED flashlight, and following the "Kenom Tutorial" at http://www.laserpointerforums.com/forums/YaBB.pl?num=1181635652 as the host body for the 250mW diode from SenKat's group buy II of 16x DVD burner diodes, here: http://www.laserpointerforums.com/forums/YaBB.pl?num=1186003362

If you want to make your own driver circuit, it can be done fairly easily with some Radio Shack parts. Daedal has a thread on building your own driver circuit here: http://www.laserpointerforums.com/forums/YaBB.pl?num=1185701612

 

[photongeek]

Thanks AJ! Lots of good info.

 

[Dandeman321]

I made a minimag laser and I am using an AixiZ laser housing. I'm still weary of it being hooked straight up to the minimag voltage since I fried my old diode with it. I'm not sure if it burned out when it shorted out or if it just gave it too much juice. Do you think a driver circuit is necessary?

 

[AJ_Dual]

Yes, the consensus seems to be that direct drive from the batteries will kill the diode.

There's lots of speculation that the guy in the instructables video used old half-dead batteries which were just right to drive the diode for awhile, maybe even the old batteries that were originally in the Mini Mag. And remember, they were presenting it as a "might as well" kind of thing with a dead DVD burner, their way you're only out the $4 for the Axiz module.

 

[LarryQ]

I built one of my lasers on a Mini Mag...

I did add a capacitor but no resistor...

It has an "Open" diode out of a 20X LG DVD burner...

New batteries..duracell..or Energizers..not a prob.........

Mine works perfectly........without a resistor....

I do limit "On" time to under 1 Min at a clip....

All In All..Awesome power, and Simple design.

Now..does this mean I got Lucky???

Maybe..But I can only report on what I have actually used.

Good Luck..and Be carefull..

Larry

 

[Gazoo]

The open diode seems to be a different animal than the closed diodes we are accustomed to working with. Of course the same precautions apply, but from what I have read they can take larger amounts of current. VaThink was able to get close to 350mw peak out of his pushing it with 650ma using a good heat sink. With a peltier, he was able to get close to 400mw peak out, pushing with 700ma. I am pushing mine with 240ma of current and might try to push it harder when I get my LPM-1.

I would really love to find the specs for the open can diodes, but so far no luck.

 

[Hemlock_Mike]

Gazoo --

I'm building up my peltier heat sink for a 20x open can now. I have everything machined and I'm waiting for my Arctic5 glue to assemble it !! I may try a GB diode first just for fun - see where I get an LED

Mike

 

[Gazoo]

Mike,
I finally got my arctic glue yesterday and glued it to the heat sink. I have a ways to go before I am done. From the limited experimenting I did with the diode from the GB, it was happier frozen...lol. I did not go much over 250ma's. I gotta admit I have abused the hell out of that diode and it hasn't turned into an LED yet...

 

[Hemlock_Mike]

That's why I got ten of them -- I abuse diodes !! That's how I find the limits. The first one is running at only 300 mA in a small c3 ultrafire. Can't leave it on too long though - There's almost no flashlight body for heatsinking.

Mike

 

[photongeek]

Hey AJ:
Regarding your Dorcy Jr. flashlight. I can't seem to find one anywhere. Can you specify a model number please and a vendor? Thanks. Will you be running off its internal driver board or are you going to make your own?

 

[AJ_Dual]

The Dorcy Jr. is availible at most Target stores in the flashlight aisle.

I was planning on using the driver in the Dorcy as-is, since Kenom has yet to blow a diode on any of the ones he's built. Although I was thinking about sticking a 47uF Tantalum capacitor in the circuit if I can find the space, a 47uF electrolytic would work just the same, but it's a larger component. Maybe just right across the lengthened diode legs you solder onto the Axiz module, to connect it to the Luxeon star heatsink base. Perhaps I can Dremel out a slot for it to fit.

However, I'm not going to pay $7 to ship a $.10 part, so if I don't see one at Radio Shack, I'll probably just skip the capacitor all together. The current and the voltage should be adequate from the Dorcy's LED driver as-is. I just thought it might be nice to flatten out any spikes when switching it on, and that might lengthen diode life.

This is the Dorcy 1 Watt from their own site: http://www.dorcy.com/products.aspx?p=414262

Here it is at Amazon. http://www.amazon.com/Dorcy-CR123-1...82-2972156?ie=UTF8&s=hi&qid=1187538363&sr=8-1

Wal-Mart has the Dorcy Metal Gear flashlight on closeout for only $7 or so in the sporting goods area. It's pretty much the same as the flashlight above, but comes in a bigger two-cell body that looks kind of like a huge bolt. The driver is probably nearly identical to the Jr. listed above. The main issue would be the difference in the head size to fit everything etc.

 

[photongeek]

AJ:
I was able to get the Dorcy Jr. at Target for $19.99. Couldn't find the Metal Gear at Walmart so they must have sold out. Now all we have to do is worry about blowing the diode when we receive them. How do you think these DIY lasers compare to a Wicked Spyder? If it even approaches comparison, then we're making $1,500.00 lasers for less than $50.00. But I'm probably way off.
Rob

 

[Gazoo]

You are better off comparing it to a wicked pulsar. But in my opinion there is no comparison. The Aixiz module focuses much better, and the power output will be much greater then even a pulsar125. And it will still be a lot cheaper.

 

[AJ_Dual]

AJ:
I was able to get the Dorcy Jr. at Target for $19.99. Couldn't find the Metal Gear at Walmart so they must have sold out. Now all we have to do is worry about blowing the diode when we receive them. How do you think these DIY lasers compare to a Wicked Spyder? If it even approaches comparison, then we're making $1,500.00 lasers for less than $50.00. But I'm probably way off.
Rob

Well, a green does cost a lot more, and I'd bet good money that MCA assemblies that can efficiently produce high output get exponentially rare as the milliwattage goes up. You can't just take any MCA off the line and put a more powerful IR pump diode behind it. The testing and verification does add some cost to be sure, though I'm not "$1,500 sure"...

This is one of the best diagrams I've ever seen of how a DPSS green laser works... http://www.kellerstudio.de/repairfaq/sam/glpmca1.gif

However, instead of saying "we're making $1,500.00 lasers for less than $50", one might say Wicked "makes $300 lasers into $1,500 ones."

The cutting/burning will probably be pretty comparable though. Unless it's materials that absorb green better than red.

 

[DD776]

Making a Maglite laser should work, just be careful with it. If you can, try another type of flashlight, but if you can't, stick with Maglite.