LM2941 low drop out regulator adjustment question

[Chris Wilson]

I am building a 12V DC in to 5 to 12V DC out adjustable voltage regulator. I used the circuit in this link at the bottom:

http://www.reuk.co.uk/wordpress/electric-circuit/lm2941-1a-low-dropout-adjustable-regulator/

and I made, as a starting point, R1 1k (1%) and R2  2.7k (1%) in series with a 10k multi turn linear pot. I find there is only any adjustment below full input voltage in the last 1.75 turns where the pot goes from 1.8k down to zero Ohms. What values for R1 and for the series resistor for R2 given I only have  1k and 10k multi turn pots and wish to maximize useful range of the pot?

Thanks!

[StillTrying]

Are you sure R1 is not accidentally 100 or 120R.

10K + 2.7k for R2 should go from 4.7V to 17.9V.

[Chris Wilson]

I measured R1 just to be sure and it's definitely 1k. I am only inputting 12V though, from a fixed supply, so ideally want the range 5v or below  to 12V less voltage drop out. thanks for the thought, easily done with multi band resistors!


EDIT, I assumed, (yeah, I know, I know.....) that the multi turn pot had its centre terminal connected to the wiper, it appears that's not the case, so I will check this out later and re-test!

[Chris Wilson]

Mea culpa, had the pot wired up wrong, works fine now, sorry for the bandwidth!!!