SimpleThings:
Well I will be using it for debugging my DC motors
Smart Car Robot Plastic Tire Wheel With DC 3-6v Gear Motor for Arduino for sale online | eBaySo +/- 5% is okay I guess and about the budget I will spend max around 30 bucks.
So could you tell me more about the project and the parts.
Alright. You'll need a programmable attenuator and/or amplifier.
This is pretty much all, really.
Actually, for reading the voltage, you don't even need that. Just use a simple resistive divider to get the voltage from 15 volts to 5. Something like 3x100k resistor would work well for this, I believe.
This gets you 1024 steps per the whole range, so 1024 steps for 15 volts. 1 step=0.0146 volts, yup, that's within your specs even with lowend resistors.
Why don't you just use a regular multimeter? logging capability, I guess?
Do you have a regular multimeter?
Is it acceptable to do the range switching manually?