I used the potentiometer code in the examples (the analogRead() reference) with a LDR instead, and I can't get large changes in value. How would I make a transistor amplifier for this case? The one I have made keeps giving me a value of 0 when the input is the collector. NPN type.
How is your LDR wired, and do you have a spec for it?
You wire an ldr differently than a pot.
To get a bigger swing make the pull up resistor larger.
If that is not enough use a transistor.
The one I have made keeps giving me a value of 0 when the input is the collector.
How are you wiring it up? Can you post a picture of the schematic?
Simply voltage divider with about 10k ohm at the 'bottom' (going to ground).
I have a 10k LDR and this pretty much give me a 90% range, from about 50 - 1000 (of 1024).