Can I use 4.5 V instead of 5V? They’re very stable on the output voltage and can kick out an amp or so. It’ll work fine. Can I use 14v adapter for a 12V device? Yes, there will be no problem. As long as the voltage of 12 Volts is same, it will work perfectly fine on a 12 Volt 1 Amp power supply as it would on a 12 Volt 0.17 Amp power supply. Experiment 2. In order to measure voltages greater than the 5 V reference voltage, you need to divide the input voltage so that the voltage actually input to the Arduino is 5 V or less. in this experiment, we will use a 90.9 kohm resistor and a 10 kohm resistor to create a 10:1 divider. This will allow us to measure voltages up to 50 V.
I would instead find a bulb that works at lower voltage- say 15V or 25 V. Mike W. The headlights in a car have exactly the parameters you desire -- about 50 watts per, and there are two of them, driven in parallel on a 12V car battery. You can easily find 40W halogen bulbs at most hardware stores that run on 12 volts of electricity (AC or DC).
Short answer: yes, you can power both with a 12V 4A supply and NO, you can't use 24V 2A supply, it will fry everything most likely. Long answer: If one or both devices is sensitive to noise (eg an audio amplifier), powering two devices from the same supply could create noise that intereferes with normal operation (eg hum in speakers). \$\begingroup\$ Alright then slightly dumber question, the pressure sensor I have takes 5v of power, while outputting a voltage between 0.5v and 4.5v. Am I correct that I am still only dividing down from 4.5v to 3.3v since even though the pressure sensor takes 5v of power, the signal it outputs will only ever be between 0.5v and 4.5v. \$\endgroup\$ A silicon diode has roughly a 0.65V drop. Putting it in series with the 4.95V from USB will get you close to 4.5V: simulate this circuit – Schematic created using CircuitLab. An LDO will also work, and will have better regulation (voltage will vary less with current) and could be closer to 4.5V.
