Single-chip temperature control

The UAA2016 from Motorola lends itself admirably to making a proportional mains-operated temperature control. A resistor with negative temperature coefficient (NTC). R3, which must have a value of about 100 kΩ at 25 °C, serves as sensor. The heating element is a 100 W light bulb, which generates enough heat for a greenhause or an environmental chamber (for testing electronic equipment).