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ArcticMyst Security by Avery

Will This Work?

Joined
Mar 10, 2009
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Im making a 445nm 1 watt labby with a 12v computer psu. I'm Planning on using an LM338t driver. Im wanting a red led (5mm Red LED - RadioShack.com) lighting up when there is power, then turning a key switch (Digi-Key Part Search) will light up a yellow led (5mm Yellow LED - RadioShack.com) then i will flip a switch (12VDC Toggle Switch with Safety Cover - RadioShack.com) which will activate a green led. Then i will be able to press a button (SPST 3-Amp "Soft-Feel" Push On-Push Off Switch - RadioShack.com) and lasing will begin. Im not very good with this, but will the combination of led's and switches cause the voltage to drop too much to lase or will there be too much voltage going to any of the switches or led's? And if i cant just hook them all up in series, how could i get it to work? May be a noob question, and i may be completely mistaken on something, so any help would be appreciated!!!
 
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Cool project. Been wanting to do something like this myself.


So just to understand, this works because you have more voltage than you will need to power your laser diode even after all the other LEDs are lit up? Or does that matter because it's (the LM338) is in parallel with the other LEDs?
 
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In parallel, voltage across all components is the same. In series, current across all components is the same. When all switches are activated, each of the four groups will have 12V across it. Each of the LEDs will draw ~10mA and the laser will draw whatever you set it to.
 
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so i dont have to have the entire lm338 driver, like in this schematic, only the rectifyer?

http://laserpointerforums.com/membe...91-lm338-constant-current-aka-ddl-circuit.jpg

No, the capacitor is not necessary unless your voltage regulator requires one (the cap in that diagram is to protect the diode from voltage spikes). The diode is a safety precaution in case you install your batteries backwards. You really only need the one external resistor to set the current. I have no idea what the last resistor is for (the one right before the laser diode) I've never seen that before in a DDL driver, maybe someone can help us out on that.
 
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