| 摘要 |
<p>The circuit has a relay (11) for opening and/or closing a gas valve, and a fail-safe circuit (12) for the relay. A regulating device is connected to an input (13) of the fail-safe circuit. The fail-safe circuit provides the relay with required voltage to open the gas valve when the input of the fail-safe circuit receives an input signal comprising two different, temporally successive frequency signals, from the regulating device.</p> |
