Need Help with a Simple Circuit Design...

[Scrappy]

(I'm new. This may be the wrong subforum.)

It's been a long time since I've designed a circuit... The input to the circuit is a temperature readout from a thermometer. I guess you could think of the temperature as a voltage (?). When the temperature is above a particular point, I want a first light to be on and a second light to be off. When the temperature is below that particular point, I want the first light to be off and the second light to be on.

 

[pakitos]

It depends on the sensor. But most probably yes. what is the sensor?

Anyways
just use a comparator (lm339) put the outpit from the sensor to the +in and a variable resistor with voltage divider configuration on -in. The output will be vcc if the temp is greater than the set voltage and zero otherwise.
connect the first light to the output of the comparator (do not forget the pull up resistor) and the second light to the output of an inverter which input is connected to the output of the comparator.
so when l1 is on l2 os off.
If yo have any questions do not hesitate to ask
GD luck