Red DIY DVD laser burner.

photongeek · Oct 31, 2007

OOOOPS, I forgot. I'm going to try to mount the heatsink outside of the Dorcy head with a little epoxy. This way, I have all of the internal head space to fit the added components. With luck, it should work.

Kenom · Nov 1, 2007

I actually am using a 2.5ohm resistor now. I was using 2 5ohm resistors or 4 10 ohm resistors and it was taking the current to 300ma roughly. by using 8 ohms your going to be dropping the current to roughly 150ma-200ma. I don't know the exact figure as I'm tired and just don't feel like figurin it out! LOL. Photongeek did you look at how I wired mine? might help you fit everything inside the head.

photongeek · Nov 1, 2007

Kenom said:
I actually am using a 2.5ohm resistor now. I was using 2 5ohm resistors or 4 10 ohm resistors and it was taking the current to 300ma roughly. by using 8 ohms your going to be dropping the current to roughly 150ma-200ma. I don't know the exact figure as I'm tired and just don't feel like figurin it out! LOL. Photongeek did you look at how I wired mine? might help you fit everything inside the head.

I'll trim those leads way down Ken. I can also make that component package a lot smaller with some careful folds and insulation.

I just hooked up my meter and learned that with 8 Ohms of resistance, the LD is drawing exactly 180ma. At this power level, it easily pops UN Sharpied balloons at twelve feet distance. Good enough? OR, should I try to boost the current by lowering the resistance? Since I don't have a laser power meter, I have no idea as to what this thing is putting out. Unless, we can derive this unknown as a function of LD known values and current draw. Would appreciate your thoughts.

Kenom · Nov 2, 2007

ya know to be honest with you, since you've got the heatsink installed on it I'd say go for it. I'd go with a 5 ohm resistor. That should get you about 200ma-250ma. Tallaxo just got one of these I made for him and he's reported it putting out 185mw!!

Oh and I love the cd-r labels you put that on to take your picture on a white background.

Gazoo · Nov 2, 2007

My GB diode puts out just above 150mw's with 240ma's of current measured with my LPM-1. So 185mw's should be easy to reach. I always refer back to Hemlock Mike's graph...lol. No doubt these diodes are powerful burners even when run at lower currents.

Kenom · Nov 2, 2007

see now gazoo I don't know for sure if we should be going by Mikes graph as a reference. Yes it was a perfect knee for his particular diode and will give us a pretty clear idea of what to roughly expect from other diodes. NOW you also need to take into consideration that his graph was made off a TEC and a passive cooler like the shaft collar is in no way going to compare to a TEC. I've built a TON of these mini's ranging from 280-360ma and the highest I've seen while testing the output was 185mw. It's actually baffled me as to why I'm not getting more ooomphf out of the diodes. Maybe my initial run was a fluke set and not as good of quality as all teh other diodes. I know the one's I'm makin now seem to visually be a bit more powerful. (you can bet as soon as I get my power meter operational i'll be testing every one I build.)

Gazoo · Nov 2, 2007

Kenom, thankfully I have learned every diode has it's own personality and will be a little different even when they come from the same batch. But not that much different unless one ends up being a freak...and they are rare. BTW, I am not running my GB diode off of a TEC... so all I am saying is if I ran a little more current into it, like 300ma's, I could easily get 185mw's out of it with no TEC. Also remember Mike's graph does correlate with Daedal's graph..

Admittedly, as the diode heats up the power output will drop.

Kenom · Nov 2, 2007

yeah so I'd say that the initial batch of diodes from that jerk that screwed senkat are not as powerful as the one's he's currently getting. All of the lower powered one's I put together were from that first batch. but the newer batch from the second GB have been hotter!

Gazoo · Nov 2, 2007

Now that is very possible. It would not surprise me if he was passing off at least some the sld1235vl's as sld1236vl's. But if I recall correctly, the diodes I am currently using came from the second batch SenKat received from him. I blew the first 5 I had in a hurry...lol.

photongeek · Nov 2, 2007

Good news ;D. AND, bad news :'(.
I kept using less and less resistance until the diode drew 215ma. Ken, I think you said that if I was within 200-250, I was fine. At this value, it popped ANY color balloon instantly and lit matches almost instantly from five feet.. Very impressive! BUT, I had this thing laid out on my bench with wires exposed and probes connected to my meter. Then the bare (stupid, stupid, stupid. I'll never learn!) leads and/or probes crossed and now the laser no longer functions. The Dorcy supply still works which rules that out so I'm assuming I blew another diode.
Do you guys agree that the crossed leads probably killed the diode? What is the duty cycle at 215ma draw? Thanks guys!

chimo · Nov 3, 2007

photongeek said:
What is the duty cycle at 215ma draw? Thanks guys!

You are using a LM317? That's continuous wave - i.e. 100% duty cycle.

photongeek · Nov 3, 2007

chimo said:
[quote author=photongeek link=1181635652/285#297 date=1194027207] What is the duty cycle at 215ma draw? Thanks guys!

You are using a LM317? That's continuous wave - i.e. 100% duty cycle.[/quote]
No Chimo. I'm just using the stock Dorcy driver with cap and resistor. I just wanted to know how long it was safe (for the LD) to leave this thing on at a current draw of 215ma.

FokoF · Nov 3, 2007

Please help!! hacked a diode out of a dvd burner and put it in a module i had lying around, it works , but the beams dot has a lot of scatter around it, any suggestions? :-?

Kenom · Nov 3, 2007

clean the lens and diode.

Kenom · Nov 3, 2007

photongeek said:
Good news ;D. AND, bad news :'(.
I kept using less and less resistance until the diode drew 215ma. Ken, I think you said that if I was within 200-250, I was fine. At this value, it popped ANY color balloon instantly and lit matches almost instantly from five feet.. Very impressive! BUT, I had this thing laid out on my bench with wires exposed and probes connected to my meter. Then the bare (stupid, stupid, stupid. I'll never learn!) leads and/or probes crossed and now the laser no longer functions. The Dorcy supply still works which rules that out so I'm assuming I blew another diode.
Do you guys agree that the crossed leads probably killed the diode? What is the duty cycle at 215ma draw? Thanks guys!

You are correct in that crossed pins killed you diode. I did it just last night myself. I hook the negative up to the battery and then go to hook the positive. I use nice little probe hooks. well I always extend the hook on the positive a little to large and it comes in contact with the negative. SPARK. every time I've done that, I've killed the diode.

At 215ma with your heatsink you should have gotten upwards to 3minutes run time without needing to turn it off.

FokoF · Nov 3, 2007

Tried didn't work :'( the dot is nice and focused its just surrounded by scatter, weird.

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