MOTM

I sent a detailed explanation about this more than a half hour ago, 
so I guess the internet ate it. Too tired to reconstruct it...

> If I simply connect an LED between the output and ground that 
> should give me ~5ma across the LED at 5V.  Another way would be to 
> tap the signal prior to the 1K resistor with another resistor going 
> to the LED.  I'm thinking either of these should work.

No, the LED forward bias voltage is fairly constant, and will 
interfere with the output. You need to drive the LED with a current, 
not a voltage. Hence the LED feedback loop - it's the easiest way to 
get a nice controllable isolated current that follows the output 
voltage. If you just want an on/off gate indicator, use a transistor 
and two resistors.

Moe