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ArcticMyst Security by Avery

To wire or not to wire, power is the question.

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I have recently discovered an interest in laser pointers and what I might be able to do with them. Experiments in light come to mind.
So, I found a set I liked, ordered them, and am patiently waiting for them to show up.
Until then, I have a spare part laser I got from an old laser level.
It works fine powered by either 2 or three AA or AAA sized batteries. (Although the original housing was designed for use with 2 AA batteries.)
My questions. How do I know how much power my laser can handle?
And
If my 3 AA batteries equal a combined voltage of 4.5v (No info re:amperage)
Then, can I use a "phone wall charger" that outputs 4.5v at 0.5A as a "fixed" power supply? (Ps. this would then be a stationary device)
I ask because I tried it earlier, but the laser did not come on. I was afraid I had burned something out, but when I used batteries, it came back on. Is there perhaps some type of voltage regulator that might shut off the power stream? Or might I simply have not been making good contact?
Any help would be appreciated.
Thanks in advance,
policetac
 





DrSid

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How powerful are the lasers ? Most 2xAA lasers should work from 4.5V power supply.
You also have to use correct polarity .. ie. plus on plus, minus on minus ..
 
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I just found this.

Powering a Laser Pointer From an External Source
Unlike high quality and expensive diode laser modules, laser pointers may have less than stellar internal regulation. Thus, you could easily destroy them instantly by attaching an external power supply, wall adapter, or even a higher capacity battery of the same voltage as the one used originally. Some pointers may even depend on the internal voltage drop inside the recommended (internal) batteries to provide some of the current regulation!

So, if you really want to run a pointer from an external source, the best thing to do would be to measure the voltage across a fresh set of batteries powering the pointer and build a highly filtered, well regulated power supply to match it. The power supply must have absolutely no overshoot or undershoot when power cycling.

Another not quite as robust alternative is to obtain a wall adapter with an adequate current rating and slightly higher voltage rating than the pointer's battery. Then, add series resistance until the voltage at the pointer is the same as when powered with its internal battery. This is risky, however, since unless the wall adapter is regulated (few are), ripple, line voltage fluctuations, and power surges will get through it - and any of these can fry a laser diode in next to zero time.

Also note that a fancy regulated power adapter may actually be deadly to a laser pointer. Power supplies that include active components (those using switchmode or linear regulators as opposed to simple wall adapters with only a transformer, rectifier, and filter capacitor) may produce sub-microsecond (or longer) overvoltage spikes when power cycled (at power-on or power-off). These will have no effect on most electronic equipment but may be fatal to laser diodes.

As far as connecting the power supply: If you don't mind drilling a hole in the case or end-cap, construct a dummy battery with contacts at each end which you wire to your external power supply. Drill a hole in the side of the case, or better yet in the cap (but off to one side so the cap will still make proper contact with the battery if you decide to use the pointer with a battery in the future) to allow the pair of wires to pass through after the cap is screwed on. There are all sorts of ways of doing this. The connections have to be made to the center spring contact on the circuit board at the bottom of the battery compartment and the case. Make sure you get the polarity correct!
 
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DrSid

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Yes .. but you ruled out all these by not killing your laser.
 
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For what it's worth, I direct drive all of my diodes for testing, with a 15VDC/5A bench PSU, switched. I've never experienced any switching or regulation problems, spikes, etc.

The $80 I spent on the PSU is a worthwhile investment to me, as it's been used to reliably test over a dozen >$100 diodes, and surely saved me that much money.
 
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993749_10201153852990019_372135512_n.jpg

This is the tip to my homemade pen. (I took the shield off for this pic as it was not an original piece.) Note the addition of the two housings? They are just that. Not part of the original unit.
969921_10201153856030095_1302880036_n.jpg

So, looking at the tip, picture it approx. 1/4" Dia. It then leads to a well (shrink rubber) insulated pair of positive (red) and Negative (black) wires.
I didn't try and get under the rubber wrap to look at it any closer.
Should I do that?
When I looked at it originally, I for some reason convinced myself that it wasn't the same kind of "circuit board" with an adjustable pot, ... (It seemed to skinny:)
I'm wrong though aren't I?
Oh. the laser is Red.
 

DrSid

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Are you sure it's laser ? Looks more like pipe-bomb :Beer:
 
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I'm starting to get the feeling that the first thing I need to do in order to experiment with my new lasers just might be to "learn" a little bit more about their construction and operation. Sounds like a crash course in Electrical theory might be in order as well. Just to start.
Thank goodness I'm a blogger who covers advancing technology in the 21st century. In my writings, I'm constantly having to cover fields of study I'm unfamiliar with, technological advancements that don't even have names yet, or are created within an industry that speaks its own language.
So, I think I'll start there.
I'll be back. Thanks for the help. I've got to go learn me some laserspeak!
 
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For what it's worth, I direct drive all of my diodes for testing, with a 15VDC/5A bench PSU, switched. I've never experienced any switching or regulation problems, spikes, etc.

The $80 I spent on the PSU is a worthwhile investment to me, as it's been used to reliably test over a dozen >$100 diodes, and surely saved me that much money.

Care to recommend a few PSU?
I am looking for one to pair up with my RGB unit too :)
(PS, I plan to move onto powering argon lasers and CO2 stuff later too, but thats in the far future )
 
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Ok. Tore it apart.
(I wasn't aware that the lens would be held in place under spring pressure as I removed the plastic retaining collar. :)
The diode circuit board was retained within a small cast Aluminum housing, and did NOT appear to have any "adjustable" components on it. (I was wondering. I suppose I was looking for a "light bulb," when I thought I saw something that appeared capable of producing a controlled spark. I'll go look it up, but until then, I'm wondering. Is this one way to control the wavelength of the beams output? If so, is this done by a control of the "temp" of the spark?)
Anyway. I figured I'd go ahead and try out a different one.
946977_10201155458550157_1321377278_n.jpg

So I'm a newbie! Hey, we all gotta start somewhere! :)
 
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For what it's worth, I direct drive all of my diodes for testing, with a 15VDC/5A bench PSU

The term "direct drive" (as we use it) is a bit of a misnomer in the sense is means the absence of a driver and ultimately no current regulation. Since you have current regulation, it is not direct driving.

Yes .. but you ruled out all these by not killing your laser.

Didn't kill != safe. The only case where that sort of increase won't cause more stress on components is with a buck driver. Nothing powered from 3V is going to be a buck unless it's an expensive IR or green.

Care to recommend a few PSU?
I am looking for one to pair up with my RGB unit too :)
(PS, I plan to move onto powering argon lasers and CO2 stuff later too, but thats in the far future )

There is no power supply in existence that can power argon, CO2, and laser diodes. CO2 is high voltage low current; diodes are low voltage high current; and argon is high voltage high current. Typical bench power supplies are low voltage high current.
 
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Im sure there is an adjustable DC power supply out there that can power all those. You will probably have to sell your car though.
 
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Ok, let's assume that Ni-Cad or other rechargeable batteries are to be used. One method we used to use back in the day for certain deices was to run a transformer in series to the batteries. Thus helping (or at least as the theory went) while you were using the device.
If not charging, the other property this procedure was rumored to have was the ability to "stabilize" the charging current in such a way as to allow its use as if it were coming from the batteries themselves.
 
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^^^^ what are you talking about. It seems like you're over thinking a pretty simple process.

Lasers are current driven devices.
Laser drivers supply the appropriate amount of current and voltage is proportional to that.
Choose correct battery config so enough voltage is supplied to for driver and for laser diode, but not soooo much voltage that the driver has to dissipate too much heat.

When batteries drain laser gets dim, take out batteries and recharge.

If you want to make a mains powered laser commonly called labby, then you don't want to use batteries at all.
You want a driver and a transformer.

Michael.
 
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Im sure there is an adjustable DC power supply out there that can power all those.

It's just as likely as the existence of a toaster/toilet/DNA sequencer combo machine. These functions are carried out by different machines and different designs. It doesn't make sense to combine them. Similarly, the electrical requirements are so different between those three laser designs, it doesn't make sense to combine the functions. Besides, argon needs auxiliary rails like 3VAC at 30A.
 




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