| 摘要 |
<p>A fail-safe timing circuit energizable in response to a starting signal for activating a system, such as a fuel ignition system or an air conditioning system, includes a first switching circuit responsive to the request signal to activate the system to commence its operation tentatively, a time-out circuit responsive to the starting signal for generating a time-out signal after a predetermined time delay interval, a circuit responsive to a system variable such as the establishment of a flame in a fuel ignition system or the sufficient increase in oil pressure of a compressor in an air conditioning system becoming a predetermined condition, such as the flame occurring or the compressor oil pressure achieving a given desired value, for preventing the time-out circuit from generating its time-out signal, and a second switching circuit for causing the first switching circuit to de-activate the system in response to the time-out signal. As a result, the system is prevented from operating in an undesirable or unwanted manner should the system variable not reach the predetermined condition within the timing interval.</p> |
