I'm planning on using a rail-to-rail input comparator like this:
100Vmax+ | 5V R |\\| |-------- |+ \\____Vout R2 5V-- |- / | |/| gnd gndWhen R2 goes beyond 5V, the output goes H.
I might use this comparator
Note 2 says the input terminals are diode clamped to the power supply rails and should be current limited to 10mA or less. ok..I can deal with that.
afaik..this circuit should work. No crazy behavior except perhaps a little glitchy around the equal input point for slow signals.
D from BC myrealaddress(at)comic(dot)com BC, Canada Posted to usenet sci.electronics.design