Circuit for an automatic furnace

摘要

An automatic furnace (1) consists of three time transmitters (2, 3 and 4), a flame-relay amplifier (5), four power supply apparatuses (6, 7, 8 and 9), a repetition circuit (10), a discharge resistor (11), a discharge zener diode (12), a voltage divider (13), a light-sensor voltage divider (14), two bias resistors (15, 16), an operating relay (AR; ar1; ar2), an auxiliary relay (HR; hr1; hr2), a flame relay (Fr; fr) and a blocking relay (Br; br). The first time transmitter (2) consists of a reference-voltage transmitter (17), a timing element (18) and an amplifier (19) which has positive feedback and is composed of an operational amplifier (19a) and a feedback element (19b; 19c) which, for its part, consists of the series circuit of a feedback zener diode (19b) and a feedback resistor (19c). The automatic furnace (1), to which an ignition transformer (ZT) and two fuel valve coils (BV1, BV2) are connected, contains a disturbance tripping path in which at least one opening contact (frb) of the flame relay (FR; fr), a first opening contact (hr1b) of the auxiliary relay (HR; hr1; hr2) and a first closing contact (ar1) of the operating relay (AR; ar1; ar2) are connected in series with a blocking relay coil (BR). A first AC voltage connection (6a; 6c) of the first power supply apparatus (6), whose DC voltage output (6d; 6c) supplies only the second time transmitter (3) and the auxiliary relay coil (HR), is ÄlacunaÜ in parallel with the first ... Original abstract incomplete. <IMAGE>