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power supply for green dpss laser

T

ters

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Hi all,

my 1st post ;D

I have recently aquired a new green laser pointer (DPSS)

and my battery DONT LAST long... just a bought a fresh AAA battery and measured the current..takes up 210mA....

now I have here a schema: 7805 voltage regulator + LM317 constant current source

my main supply is rated 12V @ 2A
main output goal: 3.5VDC @ 220mA

I still cant post a schema/link, so here is the connection :

regulated 12V supply --> 7805 --> LM317(set to 220mA CC) -->> green dpss laser pointer(<50mW)

will this do??
 





T

ters

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oh wait.. im confused... I just "peeked" inside my green laser pointer and saw a tiny trimpot.. maybe this uses EU38 laser driver... so I assume THIS internal diode driver then REGULATES the current.. right??

so I should probably reconfigure the LM317 to be a voltage controlled regulator and set its output to 3V...

are my assumptions correct?
 
E

ElektroFreak

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ters said:
oh wait.. im confused... I just "peeked" inside my green laser pointer and saw a tiny trimpot.. maybe this uses EU38 laser driver... so I assume THIS internal diode driver then REGULATES the current.. right??

[highlight]so I should probably reconfigure the LM317  to be a voltage controlled regulator and set its output  to 3V...[/highlight]

are my assumptions correct?
Click to expand...

Your assumptions are correct..
 
W

wolfblue

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ters said:
are my assumptions correct?
Click to expand...


Yes. And you can even go a little higher. Some people run "some" pointers up to 3.6V, and get a higher output that way. But running a pointer on a bench supply implies that you want to run the laser continuously. And pointers are really meant to be allowed to cool some. A minute on, a minute off. The "duty cycle". But it might be ok to run it longer even at 3.3 volts. But if it starts to get warm, about a inch back from the lens, it would need to cool down. Then you might try to rig some kind of heat sink.

--John
 
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wolfblue

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ters said:
saw a tiny trimpot..
Click to expand...

That sets the current. It has no end stops, so it will spin round and round. If you leave it at the highest output, the laser will be bright for some time and then stop working. Leave it about 75% or less. And again, watch for heat.

--John
 
T

ters

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ok guys,

thanks for the informative replies.. ;) appreciate it..

setting LM317 to -voltage controlled reg- .....

> I think ill stick to a 3v output (will try 3.5v next)

> about the "diode heating" , ill consider it.. maybe a small DC brushless fan near the pointer would keep it cool

> the trimpot? nah wont touch it... STILL dont want to ruin this pointer(its beautiful) :D no drilling holes to access pot..maybe next few years if green dpss lasers become REALLY cheap...
 
T

ters

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OK I have used the LM317 as voltage regulator... so I powered up my laser pointer...

BUT after about 15 seconds, laser light output dims up a bit.. IS THIS NORMAL??
 
lasersbee

lasersbee

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Yeah... that's normal for a cheaper Green pointer... the Xtals are probably
heating up... that's one reason why Laser Pens have a short on time... :cool:

Jerry
 
T

ters

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aw cmon...

so this problem is ONLY on the crystals?? or of the diode? Im MORE concerned of the diode...
 
lasersbee

lasersbee

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aw cmon.... :-? :-? :-? :-? :-?

The LD (diode) is an 808nm Laser Diode...
Once the LD has it's current set it's output is pretty stable it will not dim
unless the current to it drops...

How much did you pay for your laser pointer.. :-?
Where did you buy it.... :-?
What model is it... :-?
What is the output (or what is the output supposed to be)... :-?


Jerry
 
T

ters

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sorry for the flood BUT IS MUST HAVE 10 posts for ME to post PICS and schematics...
 
lasersbee

lasersbee

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ters said:
im taking few pictures now.... be back SOON.. like 5 mins...  ;)
Click to expand...

You don't need pictures to respond to the 4 questions I posted above... :-?

Jerry
 
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