- Joined
- Mar 2, 2011
- Messages
- 692
- Points
- 0
I am working on a simple driver for a a140 445nm blue diode.
I am using a simple constant current setup.
I have a set of resistors hooked up to a LM317,
set up so I can Adjust the current from 300ma to 1A.
Problem is the smallest pot radio shack had was 25ohm. So When I adjust current it is like an E^2 graph.
(Current starts at 300ma, I turn the pot half way and current is 350 3/4 of the way and its 450, then all of a suddent it jumps to 1a)
Does anyone know where to get a pot about 5 ohms or even 3 ohms?
I am currently using 2W resistors is that nessasary or would 1/4w ones work fine?
acording to my calculations there would be 1w max going through my resistors right?
I am using a simple constant current setup.
I have a set of resistors hooked up to a LM317,
set up so I can Adjust the current from 300ma to 1A.
Problem is the smallest pot radio shack had was 25ohm. So When I adjust current it is like an E^2 graph.
(Current starts at 300ma, I turn the pot half way and current is 350 3/4 of the way and its 450, then all of a suddent it jumps to 1a)
Does anyone know where to get a pot about 5 ohms or even 3 ohms?
I am currently using 2W resistors is that nessasary or would 1/4w ones work fine?
acording to my calculations there would be 1w max going through my resistors right?