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help building lm317t driver

shaun

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hey guys, im looking to build my first driver with a lm317t but i dont know what value resistors and other things i would need this is for a 300 mW laser could any of you guys help ?
thanks shaun
 



midias

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123splat

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Take that 300mW I.R. diode and put it away until you have some experience with visables (405-635nm as an example) and have read up on the safety issues. Get a red from some place like oDicForce and play around with that for a while. Then, throw that I.R. away.
Yes, that driver will work (for both). No, I don't think so. Your link is to a RED module (already has a diode/driver, just add batteries).
 

Jufran88

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I'm not too familiar with IR diodes, but you can use the DDL circuit for possibly any diode.

You just need calculate voltage needed:
Voltage drop of IR diode + 3V for LM317 + additional 1.2V for overhead

Calculate resistor for 300mA:
Reference voltage for LM317/ Current desired in Amps
1.25V/.300 = 4.167 Ohm resistor or a 4 Ohm resistor would be ok (312mA)

Regarding the module I'm not really sure what size IR diodes are, but and Aixiz module fits most laser diodes (TO-18 5.6mm).

Just a warning IR diode beams are not visible to the human eye and can be very dangerous. Wear proper goggles.
 

shaun

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i have access to protective goggles due to this being a project for my collage course and ive been told that the diode and driver could be took out and replaced but thanks for the advice anyway and is there any shipping cost to odicforce ? because i do not wish to be paying more than 10GBP for a high powered diode the only reason i was using a ir was because it was provided for me :)
thanks
shaun
 

shaun

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I'm not too familiar with IR diodes, but you can use the DDL circuit for possibly any diode.

You just need calculate voltage needed:
Voltage drop of IR diode + 3V for LM317 + additional 1.2V for overhead

Calculate resistor for 300mA:
Reference voltage for LM317/ Current desired in Amps
1.25V/.300 = 4.167 Ohm resistor or a 4 Ohm resistor would be ok (312mA)

Regarding the module I'm not really sure what size IR diodes are, but and Aixiz module fits most laser diodes (TO-18 5.6mm).

Just a warning IR diode beams are not visible to the human eye and can be very dangerous. Wear proper goggles.

thanks for this information this will be used in my work notes for the future and would you suggest that i should if using this diode to use a 4.3 ohm resistor instead to allow only 290mw max to the diode ?
thanks help is much appreciated
shaun
 

shaun

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hey guys so i am going to start of with a 100mw red laser diode i have gone throgut the parts could you guys tell me if im missing anything exept the host :
lm317t
100ohm pot
12ohm resistor
1n4001 diode
10 microfarad 16v capacitor
240mw pulsed or 100mw continues diode
is that everything ?
also what is the diffrence between pulsed and continues mode on the diode? (noob question)
thanks
shaun
 

Jufran88

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Pulsed lasers are exactly what it says they are. They emit light in the form of pulses and continuous lasers emit light continuously. :thinking:

More info here:
Sam's Laser FAQ - Preface, Introduction, What is a Laser?, Safety

It seems like you have everything you need to build your driver. However, you would need a test load to measure how much current your outputting before you connect it to your laser diode.
 

shaun

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Pulsed lasers are exactly what it says they are. They emit light in the form of pulses and continuous lasers emit light continuously. :thinking:

More info here:
Sam's Laser FAQ - Preface, Introduction, What is a Laser?, Safety

It seems like you have everything you need to build your driver. However, you would need a test load to measure how much current your outputting before you connect it to your laser diode.

would the test load be so many 1n4001 diodes with a 1ohm resistor ?
i have heard of creating a test load but have no information on what exactly would be needed,
thanks
shaun
 

Jufran88

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Yes, thats correct. You only need 4 1N4001 diodes so simulate the voltage drop of a red LD (.7*4=2.8V) and measure between the 1 ohm resistor.

The link I posted above (#2) has the information you need to create your test load.:beer:
 

shaun

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i have done some research and what i have found says i would need 4x 1n4001 diodes and a 1ohm resistor is this correct?

update*
sorry didnt see you posted that XD thanks
 
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shaun

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hey guys just wondering how many normal AA battery's would be need for this ? would it be 5 to get over 7.2 volts ? dont want to mess anything up.
thanks
shaun
 




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