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8x DVD-RW LD???

G

Galdor

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A friends old 8x DVD-RW drive kicked the bucket and they were nice enough to let me have it.
I am wondering what would be a safe current to drive an 8x LD at. Any suggestions?

Also, would voltage requirements still be around 2.5 to 3 volts?
 





G

Galdor

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Here are the speeds.

8X ± DVD Write and Read
4X ± DVD Rewrite
2.4X +R9 DL Write
24X CD Write and Read
16X CD Rewrite

I am hoping to make a deicent powered pointer out of this.
It doesn't really matter if it is capable of burning anything or not.
Any idea what this could put out as far as mW?
 
diachi

diachi

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No, we don't usually use 8X diodes around here, the lowest I've seen used is a 16X ...
 
G

Galdor

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Hmmmmmm.......

Thanks for the info. I may have to experiment.
I will give it a little longer though and see if anyone
has experimented with 8x before. Wonder if 100mA
would be a good starting point.
 
diachi

diachi

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100mA would give you less than 100mW, my guess is 60-90mW . Someone might have used one before, but I've never seen them used.
 
G

Galdor

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Cool. Thanks for your help. I will probably just have to do some experimenting and see what
happens. Guess if I blow it out it isn't too big a loss considering it is a freebie. If I get it working
and it doesn't burn out in the first hour or so I will post my findings incase anyone else decides to
use an 8x. I suppose I could start low on my current, say 50mA and see if it lases. Then I could
gradually turn it up. Problem is I wont know the limit until it blows. :-?
My only other concern would be voltage. I guess I will have to assume 2.5 to 3 volts like the rest of
the red diodes.
 
diachi

diachi

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It would be easier if you had a variable voltage supply, like I do, mines has a digital display for current and voltage, and the voltage control is analogue .

-Adam
 
daguin

daguin

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Galdor said:
I could start low on my current, say 50mA and see if it lases. Then I could
gradually turn it up. Problem is I wont know the limit until it blows.  :-?
My only other concern would be voltage. I guess I will have to assume 2.5 to 3 volts like the rest of
the red diodes.
Click to expand...

If you are paying good attention (be patient -- take small steps) you may notice what we call the "knee" before it blows.  The output graph will climb steadily until you reach the current  limit, then the output will start to drop off with increased current.  If you notice this, you can just back off about 5-10% and your diode should be fine.

Here's what it looks like when you're drawing the graph:

 
0811powergraph-1.jpg


Peace,
dave
 
G

Galdor

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@Diachi, Hmmmm, wish I did. All I have to work with is self built DDL driver circuits and a DMM.

@daguin,  thanks for the info. It looks though like I would need a laser power meter to find the knee.
Is there a different way to measure it?
 
artix

artix

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I would give it 200-250mA, That is how much current my Pulsar's diode gets.
 
rocketparrotlet

rocketparrotlet

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Yes, and so would an 8x. I've heard that you need safety glasses for anything above 30mW.

-Mark
 
billg519

billg519

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Yes, you should have good goggles. If you want to do anything up close, such as burning, engraving, etc., you need eye protection that is known good. You only have one pair of eyes. An unexpected, unplanned reflection can cause severe eye injury at these power levels. Repeated exposure to the bright laser emission at close range can cause cumulative eye damage to appear over time. This is a hobby that has to be enjoyed safely. Get the googles needed for each type of laser that you build or buy. Don't yield to the temptation to "just use some sunglasses, my buddy says that's good enough". Make sure that the goggles cover the wavelength of your laser and have a sufficient OD rating for the power of your laser and the usage planned for the laser.
 
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