Control circuit for a gas valve

摘要

Control circuit (10) for a gas valve, the control circuit (10) comprising in-put contacts (14, 21) by which the control circuit is connectable to a microprocessor, output contacts (31, 32) by which the control circuit is connectable to the gas valve to be operated, a drive circuit (11) and a fail-safe circuit (12), wherein the drive circuit (11) comprises a first transistor (19) and a second transistor (20) both being operated through the fail-safe circuit (12) on basis of a first signal provided by the microprocessor. The first signal is provided by the microprocessor at a first input contact (21) of the control circuit, namely at an input contact (21) of the fail-safe circuit (12). A first parallel connection of a resistor (33), a capacitor (34) and a first and a second diode (35, 36) being serially connected is connected between the gate and the source of the first transistor (19). A second parallel connection of a resistor (33), a capacitor (34) and a first and a second diode (35, 36) being serially connected is connected between the gate and the source of the second transistor (20). A first series connection (37) having a resistor (38) and a capacitor (39) is connected with a first contact point between the first diode (35) and the second diode (36) assigned to the first transistor (19) and with a second contact point to a first output contact (27) of the fail-safe circuit (12). A second series connection (40) having a resistor (38) and a capacitor (39) is connected with a first contact point between the first diode (35) and the second diode (36) assigned to the second transistor (20) and with a second contact point to the first output contact (27) of the fail-safe circuit (12). A series connection of the first transistor (19) and the second tran-sistor (20) is connected between a power supply contact (18) and a sec-ond output contact (28) of the fail-safe circuit (12).