> That's a very bad idea.
> When people have started to give good advoce, then abandoning what you
> are trying without listening to the advice means you are liable to
> start all over again.

That wasn't my intention, I am sorry if I sounded like that ; I was
just trying to get rid of parameters to save time for all of us.

> The problem is that you do not have a varaiable voltage, you have a
> voltage with a variable impedance.
> You CANNOT use the apparent impedance of the ADC as part of a voltage div=
ider.
> The 10k or so limit that has been discussed is nothing like the actual
> ADC impedance.
> The true ADC input impedance is
>
> =A0~~~~=3D =A0>> =A0Rinput max x 2^ADC_bits.

Where do you get that Rinput max x 2^adc ? looks interesting no such
thing in datasheet AFAIK.

>
> This is not reliable and offset voltages and bias currents may affect
> results when you try to use the ARC Rin in part of a divider.
>
> __________
>
> How to connect a pot.
>
> Pot has "top", "bottom" (of main track) and "wiper.
> Top and bottom are often interchangeable fo what you are doing.
>
> Connect top to V+
> Connect bottom to ground.
> Connect ADC_in to wiper.
>
> ADC will now see a varying =A0voltage as pot is adjusted.
>
> QED.
>
> Using a std DVM voltmeter will allow you to confirm that voltage is in
> fact varying as desired.
>
> __
>
> Now the LDR:
>
>> I connected a LDR (2 pins) connected in
>> series with 1.5v battery to analog input and conducting the same
>> configuration again, but as light hits the LDR, there seems to be no
>> change in the input voltage which it should have been.
>> Any thoughts?
>
> Same as above, the LDR must form one leg of a voltage divider. The ADC
> input resistance is essentially infinity for this purpose.
>
> Say LDR has 2 terminals A & B.
> These are usually interchangeable if it is a true LDR.
> Some electronic LDR-substitutes may care about polarity.
>
> Choose a resistor Rdiv which is somewhere =A0between =A0LDR on resistance
> and LDR off resistance.
> 10k wil robably work well.
> 100k or even 1 M may work better for some LDRs.
>
> Note that in this application you want Rdiv <=3D about 10k and LDR
> Rlight_on to be < to << 10 k.
> YMMV.
>
> Connect LDR A to V+
> Connect LDR B to ADC_In
> Connect Rdiv between ADC_in and ground.
>
> V to ADC =3D V+ x =A0Rdiv / (Rldr + Rdiv)
>
> QED

Yes configurations you mentioned works well, thank for guidance.

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