from thermometer to thermostat - switched out-put for LCD thermometer

The LCD thermometer featured in the October 1982 issue was originally intended as an ambient temperature indicator. We don"t, of course, know what you"re using it for, but from the many letters we have received asking for a switched output extension, it would appear that many of you would like to use it as a thermostat. We wouldn"t dream of disappointing you! from thermometer to thermostat from thermometer to thermostat elektor january 1984 At first glance, the circuit does not look too exciting: a preset and a comparator. Yet there"s more to it than meets the eye: after all, it has to work reliably for very long periods. Tests conducted in our own lab- oratories over a long period of time have proved the extension to be entirely trouble- free. Operation is simple: if the ambient tempera- ture rises above a value preset with P1, the relay is actuated. The relay contacts can, of course, be connected to whatever you wish: an alarm, the contacts of a room thermostat, and the like. It...