Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



LM 317 question

zerafiel

New member
Joined
Aug 16, 2007
Messages
422
Points
0
I was wondering. Why use 2 lm137 to regulate voltage and current when one might suffice? Less voltage drop this way.

Between the adj pin and the vout pin have your usual limiting resistor and potentiometer combo to control current. AND have another pot between ground and the limiting resistor or pot to control the voltage.

Would this not work? Why or why not?


Vin_lm317__C-pot_____Vout
| |
| R1
Iadj_________|___
|
V-pot
|
Grd

I left out the caps and diodes.
 



Daedal

New member
Joined
May 23, 2007
Messages
2,277
Points
0
Seems like I missed something in my DigiKey order... ;D

Thanx Chimo;
DDL
 

zerafiel

New member
Joined
Aug 16, 2007
Messages
422
Points
0
I saw those in the spec sheet as well but I'm just looking for something simple without taking too many volts. the lm200 looks nice.

Why won't it work? Medium answer?
 

chimo

New member
Joined
Jun 20, 2007
Messages
650
Points
0
The device will likely function - but not how you expect it. Adjusting one pot will affect the setting of the other.

xarylx said:
I saw those in the spec sheet as well but I'm just looking for something simple without taking too many volts. the lm200 looks nice.

Why won't it work? Medium answer?
 

Hemlock_Mike

Well-known member
Joined
Jan 7, 2007
Messages
6,284
Points
83
This looks NICE --- Gotta get a few !!  ;D  
I didn't see this in Digikey either ...

Mike

I just ordered a few -- $1.92 each !!! Data sheet looks promising - Thanks.
 

Shilood

New member
Joined
Oct 11, 2007
Messages
107
Points
0
So Mike... what's the prognosis? How did the LM200's work?

I still think 2xRCR123's should work for the BluRay GB diode even using the LM317T. Can anyone confirm this through observation?

Thanks
 




Top