I’m constantly trying to find a happy medium between current limiting resistors too large, causing too small of a current, and too small, exceeding their power ratings.

I finally got tired enough of iterating through one of these problems today that I fired up Octave and made this handy Resistor - Voltage chart for 1/4W resistors.

(Click to Enlarge)

Making the chart was fairly simple:

r = logspace(0, 7, 10000); 
emax = sqrt((0.25).*r);
loglog(r,emax)
grid
title("Maximum Voltage Chart (1/4W)")
xlabel("Resistor Value")
ylabel("Maximum Voltage")
print("ResistorVoltageChart.png")

This is why I love Octave.