445nm Labby, Over-Current?

Pardon the

So I have an A140 diode and I have been working with it for a while (sort of making that cool, power-supply labby style laser as seen elsewhere but with my own mods).

Anyway, I have it set up running on an LM317 DDL driver, set to drive it at around 1.3A with a 9V battery, with three power supplies: 8xAAs for my 12V fan (from a scrapped computer), an "outlet" for a 9V battery for the diode (fed directly through to the driver) and a male-outlet so I can power it from a wall-socket (120VAC, but I am using a wall-wart which is *supposed* to drop it down to 9V, 500mA DC).

Anyway, so it works perfectly with the 9V battery. The problem arose when I hooked up the wall-wart: it must have really-overcurrented my diode, because suddenly, there was a new hole in my futon =p The diode is fine, but I was confused.

I tested the amperage coming out and it was around 2.4A. Makes sense, but why did my diode handle that without dying?

I stuck a resistor in the circuit now though so it drops down to around 1.3A, but I don't know why it survived! Help! I can still run it at 2.4A when I choose to (added a kill switch which bypasses that resistor to drop it down to 1.3A), but what?! Why did it survive? Do I have a magical diode? I use the kill switch all the time to impress people (puts nice little hole in a CD case even when unfocused; made a hole about 1cm long by 4mm wide), but my diode hasn't died and shows no signs of dimming.

What's going on?

Re: Blu-Ray Labby, Over-Current?

it will start getting dimmer slowly
and then kind of "shut off"

Re: Blu-Ray Labby, Over-Current?

Oh... So I shouldn't be doing what I am doing? Damnit! - hope it doesn't die on me.

Re: Blu-Ray Labby, Over-Current?

...that cool, power-supply labby style laser as seen elsewhere ...

Click to expand...

Would that be my messy little project?

0th: A140 diode is not BluRay! lurk moar
1st of all, I'm wondering how you're getting 2.4A out of a 500ma wall-wart.:thinking:
How did you measure this anyway, what method, where and how did you put your DMM?
2nd, you don't need 8xAAs to run a 12V fan, they will run happily on 7~8V as well.
3rd, where exactly did you put that extra resistor?
4th, pictures!:wave:

My crystal ball says:
You're measurements are off.
When you're running it off the little 9V battery, you're diode is barely getting enough
current to lase, maybe 300mA.
When you give it the 500 maybe 600, 700 mA the wall-wart is able to provide,
the diode comes alive, bright beam, hooray it burns all of a sudden!

Re: Blu-Ray Labby, Over-Current?

Yes, it would be your messy little project! I feel like I have improved upon it, though, mebbe? ^_^ Mebbe not.

0th: Yeah - my bad.
1st: I have no clue how I managed that, to be honest =p It may be a faulty wall-wart? I measured this in a couple of ways so I could make sure my readings were accurate. Trust me, I was just as stunned as you were. First, I hooked it up all normal like to my DDL driver, then hooked that up to my test-load (6 1N4001 diodes, a 1 Ohm resistor, you know, normal stuff), and put my DMM on voltage to measure across the resistor - read 2.4V :O Then my resistor started smoking, so I pulled it off quickly. Nonetheless, I got a nice, constant 2.4V. After that, I needed to confirm so I just used my DMM to measure amperage across the leads going out from the driver, and that read 2.4A. Then I checked the amperage across the leads of the powersupply, and that read 2.4A. It's pretty consistent.

2nd: Oh. Well, that is... good to know, I guess? Saves power ^_^

3rd: That extra resistor went between the negative lead of the power supply from the outlet and a wire I have hooked up to my driver. The "kill-switch" bypasses the resistor.

4th: I guess I could.... Maybe later when I have the time... right now I am trying to get my girlfriend not to break up with me over past issues. Anyway, irrelevant here, I guess.

Regarding your crystal ball... I definitely think that my measurements are pretty accurate. My 9V battery powered laser is capable of burning leather from about 10 feet away (within a few seconds), will light a white match instantly, and will burn my white hand in about 2 seconds. Also, you can see the beam dimly in my lair (which is a very bright room), and when it's on "kill-mode", the beam is clear, and will put a hole in anything just about instantly. (By the way, the 9V and the wall-wart without the kill switch activated are about exactly the same brightness, so... yeah.)

By the way: Just tested out my dinky little 9V battery and it was capable of putting out 1.4A without any issues (just stuck my multimeter directly onto the leads to get that).

Hmm. Interesting. What may have been happening was that the diode I thought was 1 Ohm turned out to be 2.2 Ohms (must have been burned a bit or something). I measured 930mV across that resistor I just soldered from my driver to my diode to check the amperage. Hmm....

So yeah - I think you are right. Just did further measurements with that diode *assuming it is 2.2 Ohms instead of 1 Ohm* and that gave me results at about 321mA with the 9V battery. You are correct, sir! Damnit! Now I have to go rework the circuit and everything... frack! At least it will be stronger in the end.

Okay, so no matter what I do to my driver, I can't seem to shove it past around 650mA. It just won't budge.

Basically, my circuit is like this:

In+ -- LM317 ------------------------------------------------- Out+
.............|.........>...............>..............>......|.......|.........|
.............|......10Ohm......10Ohm.........0.5Ohm |......^.....10uF cap
..............------<----------<-----------<-----.....1N4001...|
........................................................................|.........|
In(-) ---------------------------------------------------------Out(-)

(Ignore the dots, it makes more sense that way.

That's the lowest resistance I can get....

What am I doing wrong? Why can't I get more amperage from my 9V *or* my wall-wart?

LM317 will be glowing and get pretty hot if you try and run it near 1A...

TTerbo said:

LM317 will be glowing and get pretty hot if you try and run it near 1A...

Click to expand...

It won't be glowing...they should be heatsinked at that current but they're designed to go to 1.5A.

So is there a way to run my DDL drive at around 1.3A or so? I have managed to drive it up to 750mA so far... but I can't seem to get it any further (that's with two .5Ohm resistors and a 10Ohm resistor in parallel).

EDIT: So I got it to around 1A in current I think (or around 1.2, I don't remember) by redesigning my driver so that the two .5Ohm resistors are running in a series now.

Turns out that my "1A" current I was getting was actually around 820mA. I wired up one 1Ohm resistor in parallel with a .5Ohm and another .5Ohm and I am pushing at around 940mA.

Wolfman29 said:

Anyway, I have it set up running on an LM317 DDL driver, set to drive it at around 1.3A with a 9V battery, with three power supplies: 8xAAs for my 12V fan (from a scrapped computer), an "outlet" for a 9V battery for the diode (fed directly through to the driver) and a male-outlet so I can power it from a wall-socket (120VAC, but I am using a wall-wart which is *supposed* to drop it down to 9V, 500mA DC).

Click to expand...

Ok.. am I the only one who noticed these things?

A 9V will NOT source enough current to drive a a 445 at 1.3A.. Neither will a 500mA 9v wall wart. My only guess is that when you used the AC power, you still had the 9v hooked up and both together were able to source enough current to actually drive your laser at 1.3A.. Though i'm curious how you have this wired, since if they're just paralleled, that would mean if you had a battery attached, and power on from the wall wart, and the laser was off, that would mean it would be trying to recharge a most likely non-rechargable 9v... which would lead to bad things happening in a hurry.

qumefox said:

Ok.. am I the only one who noticed these things?

Click to expand...

Of course not, as you can read in post #4.

AH. guess that's what I get for skimming

Yeah, I realized where all my wrong readings were coming from.

Turns out, however, that my Wall-Wart *is* capable of driving it at around .94A, which is where it's sitting right now (my resistance is hovering somewhere around... well, I have .5Ohm, 0.5Ohm, and 1Ohm all in parallel. You do the math =p ).

Anyway, once I get more cash to spend, I will get more resistors so I can wire up a better driver.

Anyway, how much voltage would be necessary to run a 445 at 1.3A?

If you mean the battery issues.. It's not the voltage. It's the amount of current the battery can source. 9V batteries aren't really one battery, They're really 6 small 1.5v batteries in series inside a rectangular canister. As far as voltage, your DDL type driver needs whatever Vf the diode is at 1.3A + about 2V. Which means your minimum input voltage to the driver will need to be around 7V. What matters more is current though. You'll need a battery that can source at least an amp. The best option would probably be two 18650's in series, but you could always use something like 7 or 8 D-cells in series as well. heh.