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can i use this for a labby?

lasersbee

lasersbee

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jwwilson23 said:
Well i would probably rather just go with a fixed resistor or maybe add a pot in after i add in maybe half of what i need in fixed and that 1n5 diode or whatever isn't that fir reverse polarity? And capacitor isn't exactly needed but good. t can also be bad if u forget to discharge it in between batt changes i believe.
Click to expand...

If you don't want to blow your Laser Diode I would
highly suggest that you build the tested Current
Driver circuit in Post #13. Don't shortcut the parts...
They are there for a reason (to help protect the LD).


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
 
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jwwilson23

jwwilson23

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lasersbee said:
If you don't want to blow your Laser Diode I would
highly suggest that you build the tested Current
Driver circuit in Post #13. Don't shortcut the parts...
They are there for a reason (to help protect the LD).


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
Click to expand...

ok i see that its for a phr is there anything else (besides the resistors) that would have to be changed?
:thanks: Justin

EDIT- about the pic in post 13 how is that circuit putting out only 125ma of current to the diode.
 
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danielone

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How much mA do you need ? If 300mA you will need a 4,3 Ω resistor max. mA for a LPC-826 was 440mA i recommend using 350mA but you wont get that out of the adaptor...
 
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jwwilson23

jwwilson23

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how did you come up with a 3 or 4 ohm resistor? that would mean you are putting only 1 volt in, i dont think that is right...


EDIT-well now i think you are right... but if the 1 volt is correct please explain
 
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jwwilson23

jwwilson23

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so for this equation i would plug in 1.25 for volts (R=V/I)

if thats what you are saying then damn i have been over thinking it or not reading into enough detail

EDIT-damn it was that simple thanks! i just could not find your answer anywhere i thought you subtracted 1.25 from the voltage you are putting in and then divide that by desired current :(

so 10ohms in paralell would only be putting out 250ma
 
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IsaacT

IsaacT

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Its so simple it is complicated IMO. I want 125mA current....oh I need a 10Ohm resistor. Bing bang bop, I have my driver. haha
 
jwwilson23

jwwilson23

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yea :), thank you for the help (again:))
and there isnt any 3 ohm resistors right :D so how would one calculate what resistors to paralell in order to acheive 3 ohms for 416ma or maybe 4ohms for 312ma
 
IsaacT

IsaacT

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3 10ohm resistors in parallel would achieve 3.33ohm resistance, which in turn would give you 375mA of current. does that help?

PS-I have ZERO in depth knowledge of resistors, but I am good at following formulas. So since 10ohm resistors are all I have ever used, I just worked with those. There might be an easier method.
 
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jwwilson23

jwwilson23

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alright thanks, and yea i just know the formulas for resistance, voltage, and current for both series and parallel i just wasn't sure about what my options were buying wise.
:beer: Justin
 
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danielone

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I think its not important how much voltage Input ges into the LM317 it can be used as a Voltage Regulator or a current regulator (CC out) 7,2 V would be best input for a red diode so you need to drop your Voltage for your AC/DC adaptor i would use a resistor when its Output is CV when not use a CV driver set to 7,2 V Out. .
 
jwwilson23

jwwilson23

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so do i need 2 lm317 one for CV and one for a CC. i now know how to do a CC but what about CV
 
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danielone

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Did you checked your adaptor for CV when its not CV like 8-15 V you will need another LM317 for CV you will Post a circuit how you make CV with LM317.
 
Cyparagon

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theres-are-all-horrible-posts.jpg


Choose your diode first.
Choose a driver that is capable of running it.
Choose a power source that is the acceptable input range required by the driver.

Where the hell did a constant voltage setup come from? Not needed - wasteful, even. Keep it simple, stupid.
For a DVD diode / lm317 driver, it's a 7V+ wallwart with 500mA rating or more.
 
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danielone

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So when its getting from 7 V to 20 V you wouldn't need anything to safe your diode ok no problem ...when you have enough money
 
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