| 摘要 |
<p>An enclosure for a stable voltage reference or quartz oscillator has a two stage heating system to provide rapid and fine control of the temperature. This control is effected by control of a heating element from a voltage regulator. The voltage regulator circuit (22) is connected to a dc voltage source (V) and the regulated output (c) is connected to a bridge circuit. The bridge circuit comprises a non linear resistor (RT1) with positive temperature coefficient, which is attached to the wall of the enclosure. This is in series with a second resistor (R5) to form a voltage divider for the base of a transistor (Q1). This transistor drives a second transistor (Q2) which is in thermal contact with the enclosure to heat it.</p> |
