LPC-815 not what I expected...

[iamonk]

First off, complete newbie here, but have been reading threads for a couple of weeks.
I bought an LPC-815, a rkcstr drive, Aixis module w/ glass lens, and 2 cr123 lithiums.
Got em powered up and I'm less than impressed by what I have been reading.
I can burn, well more like etch electrical tape, dark woods, but not white paper.
I can also really piss off a spider but not enough for him to DIE!!!
I double checked things with another LD, driver, even pumped 12V into the rkcstr and got the same results, except the board got pretty hot.
The Aixis module has never gotten hot, barely warm in my opinion, definately no reason for a heatsink and I powered it with the cr123's for 15 at a time.
The batts were new when I started, and though the ouput is now reading 5.5V, the burning capability has not really diminished.
I am seeing 2.7V at the diode, putting my meter in series with the diode, I see 340ma.
I have the pot on the driver cranked all the way up.
Am I seeing realistic results, or is something wrong here?
My goal is to add wood burning capabilities to my CNC router, but with these results, I'd have to run this a like 1in/min. Am I expecting too much here? Do I need to go IR?

 

[billg519]

Red is not a good color choice for burning white paper or cardstock. A bluray will easily burn through white paper.

I have one of these reds running at 350mA, it cuts the tape no problem.Are / were your batteries fully charged?

Depending on what you need to cut or etch with your cnc will determine the choice of laser.

 

[iamonk]

I was originally gonna go Bluray, but for the price, I didn't want them to be my first.
I did run some tests and came up with some interesting results.
Since I have 2 more LOC's, I decided to go all out and see what I could get out of this one.
I took the driver out of the picture...wired my meter in series with the diode...soldered 4 2ohm power resistors together...
Batts at 5.5V, 8ohms, lame output.
6ohms @350ma about the burning capabilities as with the driver
4ohms @400ma not much of noticable difference
2ohms @600ma a bit better, burns white cardstock now
I stopped at this point because the housing was finally getting hot.
Now I want to turn up a decent heatsink and see how long the thing lasts.
It did go for at least 20 seconds at 600ma(assuming my meter is accurate).
Why does this all sound wrong?
I can hear Taps playing already.

 

[iamonk]

Yep, bad idea to fire up a cold laser.
It was going to die anyway, but should have warmed it up a bit.
It's demise was uneventful, I didn't even get the chance to see it for more than a second.
Oh well, 2 more to go.
Got an IR coming as well.
Maybe I'll try burning out a Bluray.

 

[jayrob]

At 340mA's, your probably only just above 200mW's. (AixiZ acrylic)

But if you have an AixiZ glass lens, it will be about 5% more.

This same diode will give about 295mW's at 420mA's. (650-G-1 glass lens)

 

[iamonk]

Thanks guys for the responses, the batts are drained a little, and from what I'm reading are a little on the light side. 2X 3.6V seems more like what I want. I am using the glass lens, but the difference isn't noticable at this point. I just got another diode set up in a module, and if it weren't for the snow, I'd go out for some 3.6V's. I'd like to see if I can get more than 350ma out of the rkcstr. In my opinion 450Ma might work for what I want to do. Maybe I'll have to build my own drive, definately won't be as compact. Hmmm kinda wondering what the 1W is going to do.

 

[Benm]

It might increase power a bit, but its probably not a very good idea to run it at 450 mA or more in a CNC or any other setup where the laser is on for quite long.

200 mW is already much more continous power than what the diode is rated for. Obviously you can sacrifice some lifetime compared to what is expected of a dvd drive, but the harder you push it, the shorter it will live.

At your experimental 600 mA, life could be just minutes, although it varies wildly between individual diodes. Some will go 'poof' in no time, others seem to be almost immortal.

 

[iamonk]

If it comes down to an issue of heat, a pelt and decent heatsink should do fine.
From what i saw 600ma in would work nice I think.
With the CNC, I have more options than if I were building a pointer.
I have a 1W IR coming, and am curious to see what that will do.
In the mean time, these lpc-815's make a nice beam for a LOOONG distance.
The rkcstr fits nicely in the Aixis, add some small batts an you get a nice small package.
I'm thinking now that my 357magnum needs a laser sight.

 

[Greenmechanic]

It might increase power a bit, but its probably not a very good idea to run it at 450 mA or more in a CNC or any other setup where the laser is on for quite long.

200 mW is already much more continous power than what the diode is rated for. Obviously you can sacrifice some lifetime compared to what is expected of a dvd drive, but the harder you push it, the shorter it will live.

At your experimental 600 mA, life could be just minutes, although it varies wildly between individual diodes. Some will go 'poof' in no time, others seem to be almost immortal.

I have a LOC running at 520mA.
It has 5-6 hours on it so far, with no problems. 650-G-1 lens.
It will burn thru a CD case in <4 seconds.
Hopefully this is one of the "immortal" ones.

 

[danq]

This doesn't address your original question, but...

Caution - when you measure the current with the meter in series with the LD, you may not be measuring the actual current that will flow without the meter in there (this is called "insertion loss"). The amount of difference will depend on characteristics of the driver - how well it regulates, for one; and the internal resistance of your meter. Most meters have a significant resistance when in the range of currents we're measuring.

If there is enough difference, when you connect the LD directly you may get over-current.

A far better way to measure current is to put a very low resistance in series, and measure the voltage across that resistor (assuming you can't measure the voltage across the driver's own sense resistor). A 1-ohm resistor is easy because the current value will equal the voltage; but I use a 0.1 ohm to minimize the insertion loss.

forgive me if you already know this, it's something that a lot of people don't know.


DanQ

 

[iamonk]

I guess the best way to learn is to try and fail.
I believe voltage was the problem.
At first I went with 2 cr123's, no good.
Then I shelled aout for a pair of 3.6V's.
Still not enough current.
I built a DDL driver, double and triple checked everything, but still lacked power.
At 7.2V I figured I would get some decent output.
I went as far using only a 1ohm resistor to set the current, but not only did I not see the current ouput I was looking for, but things didn't even seem to heat up all that much.
I went for broke and decided to go back to the beginning with 5ohms to adjust current, but this time use 12v as the power source.
Only now did I see the current I was expecting.
So now I have a very ugly looking board, but with 2 ohms to adjust, I can blow a hole through electrical tape instantly, burn cardboard just about as fast, and not as quickly burn white cardstock.
The LD is in an AIXIS housing with no sink and really doesn't get as warm as I'd expect, but the 317(also unsinked) will burn you.
Since I managed to keep this LD alive through all this, I'm going to push it a little further after I make up some heatsinks.
My conclusion would be that if you want to get close to 500ma from the drive, you need more than 7.2v. It seems to give 250ma without problem on batts, but beyond that, I couldn't get it to do it.
I didn't try a bigger cap, but I can't say if that would make a difference or not since my electronics knowledge is limited.
Anywho, this diode seems to be pretty durable so far.

 

[iamonk]

Ok, got a little impatient and blew another diode.
They go pretty quick at 12V.
What I did find is that this one lasted about 10min constant running at @600ma unsinked.
I had an AIXIS plastic lens in it at the time, and it got a bit melted inside.
I think my testing is done for now, only have one diode left.
I got a housing turned up for use on my router, and the driver is all set.
I just need to run the trigger and I can start burning.