yikes... I was just reviewing the schematic, and I got a decimal wrong... R1-R4 shouldn't be 1.0k, they should be 10 ohm. 33mA across 1k will try to drop 33v, not 33mV like I was trying to do. Across 10 ohm they will drop 330mV. That means R13 can be 1k instead of 100... this will set the reference input to 238mV. If the LED is on, the (+) input will be at 330mV, and since the (+) > (-), the output will be (+), turning the transistor and relay off. If the LED is off (open circuit), then the (+) < (-), and the output of that comparator will be (-). Since the comparators are open collector, you can tie all outputs together, and when one turns on the output goes low and turns on the transistor/relay.