i just don't get it ! the lm317

[newbie noob]

i don't understand how only a couple of voltages drops in the lm317 ,when the thread about building a driver here tells u to put a 7.2 voltage supply and the red laser diode requires only 3 volts !
how is that ? wouldnt it just burn the red laser diode ?
can sum1 explain to me a little further about the lm317 ?
what is the highest voltage that red laser diode can handle ?
btw i burned already like 10 diodes !

 

[lasersbee]

The information is on the Forum... you just need to do
a little research and reading...

The LM317 regulator set up as a Current regulator will
REGULATE the current that the LM317 is set to and that
Laser Diode requires.

Why have you burnt 10 LDs....:thinking:
Why have you not used a Dummy Test load...

That info is also posted all over the Forum...
Just do some reading....

You can start by reading the LM317 Data Sheet....

http://www.national.com/ds/LM/LM117.pdf


Jerry

 

[newbie noob]

The information is on the Forum... you just need to do
a little research and reading...

The LM317 regulator set up as a Current regulator will
REGULATE the current that the LM317 is set to and that
Laser Diode requires.

Why have you burnt 10 LDs....:thinking:
Why have you not used a Dummy Test load...

That info is also posted all over the Forum...
Just do some reading....

You can start by reading the LM317 Data Sheet....

http://www.national.com/ds/LM/LM117.pdf


Jerry

actully iv read much about it , but understood a little ! , the one simple question i have is what if i put a 9 volts input voltage , with (10/10)=5 ohm resistors and a potent-meter 100 ohm , what the v out would be then ?
another question is , when v out = 1.25 (1+r2/r1) what if the potent meter was set to maximum (100 ohm) then the v out would be really high , much higher than 3 volts which is the max voltage that a ld can handle !
did u get me here ?

 

[bennett326]

actully iv read much about it , but understood a little ! , the one simple question i have is what if i put a 9 volts input voltage , with (10/10)=5 ohm resistors and a potent-meter 100 ohm , what the v out would be then ?
another question is , when v out = 1.25 (1+r2/r1) what if the potent meter was set to maximum (100 ohm) then the v out would be really high , much higher than 3 volts which is the max voltage that a ld can handle !
did u get me here ?

o my gosh we are not regulating voltage here we are regulating current

laser diodes are current devices we need to regulate the current not the voltage

and no i don't "get you here" because you obviously have read nothing

otherwise you would have understood what lasersbee said :can:

 

[midias]

^ relax man this forum can be ultra unfriendly.


The formula you are using if for voltage regulation in the standard LM317 configuration


You want this config

This will set the voltage to whatever is required to make the current you select.

read this

Current source - Wikipedia, the free encyclopedia

 

[bennett326]

ya sorry i was a bit rude it just annoys me when people are spoon fed information and reject it :undecided:

 

[lasersbee]

^^^ Ditto

Jerry

 

[bennett326]

^^^ Ditto

Jerry

thanks for the rep :beer:

honestly its very easy to build a laser without a single question, its amazing how much information is on this forum

Laser driver - It can be done
and the how to build a laser thread is all you need

it works i did it :crackup::crackup:

 

[notahardwareguy]

So right you are. I did a fully DYI build (to include driver) too. The amount of information on this forum is just AMAZING and my experience has been that most folks here are more than happy to help with advice and information! :gh: