To make the pot less sensitive use a 2k fixed and a 500 Ohms pot in
series so your pot only adjusts
A smaller range, giving you a lot finer adjustment

PC

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Lucian
Sent: Saturday, May 15, 2004 7:57 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: [EE:] Adjusting LM338 output voltage [Was: Cascading
Regulators]


In the datasheet, it says that the equation to adjust Vout is:

Vout = 1.25 (1 + R2/R1)

In my case, R1 is 220R, and I calculated R2 for three voltage values:

10V - 1.5K
13.8V - 2.2K
20V - 3.3K

Is it OK to ignore Iadj*R2 term (as they mention that Iadj is minimized)
and to only have a 5K potentiometer as R2 ?

Lucian

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