Here is another email from a user that has a perfect question regarding power supply voltage... check it out!! This is the exact question (in blue) and my reply (in black)
No problem at all, and great research! I always love when people like you utilize the website and have almost all your own answers!
You're close :) All you have to do is increase the resistance of your circuit to account for the lowest power supply voltage.
Just play with ohms law to see how much you need to add, but here is the link to the main page for resistance modification
You'll be adding resistance in series with your nichrome wire circuit.
Here is a quick series of calculations you can do, figuring the lowest voltage your power supply can output. Lets just use 2 volts (just guessing) as the lowest voltage your supply can provide.
Resistance = Voltage / CurrentResistance = 2/6.5Necessary Circuit Resistance = 0.307 ohmsResistance of 1 inch 18 gauge wire = 0.035ohmsUnaccounted Resistance = 0.307 - 0.035ohmsUnaccounted Resistance = 0.272 ohmsSo basically, all you have to do is add about 0.3 ohms and you can use a power supply that can only go as low as 2 volts (theoretical).
Otherwise check out Digi-Key, this link goes straight to their resistor search page
On hand, I have 1ohm5Watt resistors. So placing a handful in series or combined series / parallel will provide a lot of circuits with the resistance and wattage they'd require.
I hope that wasn't too confusing!!