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Voltage of open can long die?

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BeavRat

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What should I set the voltage at for a long die open can red diode using the ddl driver. Right now I am inputing 6 volts with 2.8 volts at the diode and 300mA. Can I go higher than 6 volts for the input voltage and bump up the mA to 350?

Thanks
 





You can go to 420ma and be ok on a long open can.
The voltage stays the same at the laser, its only current that changes.
Really the DDL driver needs at least 7 volts to run efficiently, if I'm not mistaken, but could run on 12 volts, with serious heat sinking on the 317. Add another AA to it if you can, but for now 6v is ok i guess.
Make since? if not post for more help.



WOW 100 posts!!!!! ;D
 
Note how the LM317T circuit is a voltage regulating circuit. ;) You can insert as much input voltage as you want. Yes, a red diode typically takes around 3v. You can adjust the current output with the potentiometer in the circuit, without increasing the input voltage.
 
Jimmymcjimthejim said:
Note how the LM317T circuit is a voltage regulating circuit. ;) You can insert as much input voltage as you want. Yes, a red diode typically takes around 3v. You can adjust the current output with the potentiometer in the circuit, without increasing the input voltage.
Click to expand...
In DDL's circuit the LM317 is used as a current regulator, so the voltage doesn't really matter. You could power that circuit with 35 volts and your only problem would be heatsinking the LM317. The laser diode takes the voltage it needs so extra voltage won't hurt the diode. The only thing you need to watch is the current.
 
styropyro said:
[quote author=Jimmymcjimthejim link=1228373308/0#3 date=1228448652]Note how the LM317T circuit is a voltage regulating circuit. ;) You can insert as much input voltage as you want. Yes, a red diode typically takes around 3v. You can adjust the current output with the potentiometer in the circuit, without increasing the input voltage.
Click to expand...
In DDL's circuit the LM317 is used as a current regulator, so the voltage doesn't really matter. You could power that circuit with 35 volts and your only problem would be heatsinking the LM317. The laser diode takes the voltage it needs so extra voltage won't hurt the diode. The only thing you need to watch is the current.[/quote]
Thanks for the clarification. :)
 
Oh, so the diode only takes the voltage it needs. Are you saying it would wourk even if you input 9 volts?
 
Yes, up to 35 volts, the laser only will get the 3 volts it needs to run and the LM317T dissipates the rest as heat. Note at those levels the heat sinking.
 
jonrobertd said:
Yes, up to 35 volts, the laser only will get the 3 volts it needs to run and the LM317T dissipates the rest as heat. Note at those levels the heat sinking.
Click to expand...

Yes, *lots* of heatsinking... Plus you'd also need to make sure your capacitors and everything else were rated for those voltages... But yeah, no matter what voltage you put in, you always get out a specific current.. The diode only takes the voltage it needs to achieve this current.

You'll be fine up to 400mA, 450mA is pushing it, some people have been very lucky and were able to drive theirs at 500mA with good heatsinking.. The general consensus is that 420mA is the sweet spot in terms of power and long life.
 
i have a question too what mA should i put out to my LD using a flex drive if i want it to be a burning laser what would give it long life and be able to burn stuff should i go with 420mA that sounds high to me :-[ I plan on putting it in a dorcy jr with the full dark horse heat sink.
 
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