Semiconductor Diodes and Transistors as Electrical Thermometers

Electrical thermometers for laboratory experiments, environmental testing, and flight performance of rocket‐borne equipment may be realized with simple semiconductor circuits. The devices described here utilize the variation with temperature of voltage across a forward‐conducting p‐n junction. This voltage variation of approximately 2 mv/°C is virtually linear over the entire test range of −40 to +100°C. A diode used in conjunction with a microammeter to measure the voltage across the diode is most convenient for laboratory use. For airborne use, where a signal varying from 0 to 5 v is required for telemetry, the transistor circuit is ideal. The latter circuit, which amplifies its own base‐emitter junction voltage variations, requires only a single transistor and 3 resistors. Adjustment of two of the resistance values enables the user to select any temperature range to be covered with the desired sensitivity.