Im using an lm35 chip for a temp control circuit im trying to make, but im having trouble figuring out the comparator that i need, was going to use a 741 op amp, but what resistors do i need etc? :S I want it so that the circuit turns the output of the 741 on @ 35C and off @ 28C. Ne ideas / suggestions? Im not after a full circuit, just some help with how to work out what i need..
I'd advise against a 741, go for an op-amp designed for single-rail supplies & that will swing down to near-zero. For the 28°-35°C hysteresis, one way is a dual op-amp, so switch-on and switch-off points can be set. An LM358 would be good. I've a circuit somewhere...
None on my site, and the one I thought I had turns out to be a window comparator, & would be on between 28 & 35, but off above 35 or below 28
