heatsink thermometer

heatsink thermometer This thermometer was designed for measuring the heatsink temperature of a Crescendo power amplifier, but it can, of course, be used for other power amplifiers and indeed for other applications. The thermometer does not only display the temperature of the heatsink on two displays, but it also provides a switched output which, for instance, can be used to switch on a fan if the temperature rises above a pre-determined value. The circuit consists of four parts: a reference voltage source,ICl, the sensor, 1C4, the display section, IC2 and IC3 and the switch section, IC5. Cl, a 723, provides a stable supply voltage for the sensor and switch section. This voltage is about 8 V. The temperature sensor provides a temperature dependent voltage of 10 m V/K. At 0°C, for instance, the voltage across 1C4 amounts to 273 x 0.01 = 2.73 V (00C = 273 K) The display section is constructed around two old faithfuls: ICs CA 3161E and CA 3162E. IC2 con- tains the A/D converter and t...