Hi Guys,

As the titles alludes to, I am trying to figure out what size resistor I need when using a voltage divider on a PIC as an input trigger.

My circuit is being powered by a voltage regulator and I have been using an optocoupler to trigger my PIC, but am trying to minimize cost, so switching to a voltage divider setup. What I am trying to figure out is can I use two 1/8 watt resistors in my VD circuit along with a .1 uF cap and Zener, to make sure my circuit doesn't go above 5 volts?

For my 12 volt circuit, I have calculated using 10k and 4.7k, which gives me just under 5 volts. Is it safe to use two 1/8 watt resistors or should I bump the 10k to 1/2 watt or 1/4 watt? This is the only things that's stumping me. The input can either be momentary or continuous (if that matters).

Thanks,
Tony