Simple devices with OP-AMP

Question

our teacher wants us to submit a proposal / project proposal. any device that uses op-amp is acceptable. where can i find some?

Answer 1

an automatic emergency light - one which lights up when there is darkness(incorporating an LDR) or the one that lights up when power goes might use an opamp (as a converter) to the acheive the automatic switching.

Answer 2

... or an automatic fan for inside the car:

See bottom of  http://www.uoguelph.ca/~antoon/gadgets/7...

When it gets too hot in the car, it turns the fan on.