Abstract: The present invention relates to a digital control circuit which controls the drive of a load by the use of a clock pulse. More particularly, it relates to an integrated circuit device for combustion control which controls the combustion of a burner in a water heater, an air heater or the like. A combustion control circuit performs an ignition operation for a predetermined time, and stops the supply of fuel in case of misfire. When the reception of the time-keeping clock pulses has stopped within the predetermined time, such predetermined time will become infinite, and in the case of misfire, the fuel supply will continue dangerously.

Abstract: A flame detecting apparatus used in a combustion control apparatus for a water heater provided with a gas burner comprises a pressure switch serving as means for detecting presence or absence of flame and a voltage comparison circuit serving as means for determining the presence or absence of the flame on the basis of the input signal supplied by the pressure switch. The voltage comparison circuit has an offset voltage and has a non-inverting input terminal connected only to the ground.

Abstract: In a digital control circuit, a clock pulse is counted so that when a predetermined timing is reached the driving of a load is controlled. The digital control circuit may preferably be an integrated circuit for controlling the combustion of a burner for a combustion apparatus such as a water heater or an air heater. The combustion control circuit performs the igniting operation for a predetermined period of time and the supply of fuel is stopped if the ignition can not be attained within the predetermined period.

Abstract: A combustion controlling apparatus is disclosed which is used in a pulse combustion apparatus for generating flames intermittently and which has a flame-rod type flame detector. In this combustion controlling apparatus, a low AC source voltage is converted to a DC voltage and then this DC voltge is converted by an inverter to an AC of about 100 V and 800 Hz which is then supplied to the igniter and flame rod. The inverter comprises a pair of transistors and a transformer having a primary winding with its center tap connected to a DC source voltage and both ends thereof connected to the respective collectors of the transistors which are in turn cross-coupled to the bases of the mating ones through respective series circuits each consisting of a capacitor and a resistor. Thus, in a secondary winding of the transformer, a rectangular wave voltage is produced. The inverter can supply a high voltage to the flame rod during ignition, enabling easy fire detection and can prevent the transistors from generating heat.

Abstract: A combustion control circuit including semiconductor integrated circuits used for control of a combustor or burner of a water heater, air heater-blower or the like has a very simple configuration for stable initialization against the transient condition of a source voltage. A logic gate performs a sequence control. An input interface section applies a signal to the logic gate in response to an input signal required for combustion control. An output interface section converts the signal produced from the logic gate into a combustion control signal. An operation start signal from an operation switch or a temperature detector circuit is used in combination with an initialization signal for the combustion control circuit.

Abstract: A combustion control apparatus in which a predetermined number of pre-purge and igniting cycles are repeated until ignition takes place successfully. A pre-purge time interval of the second and subsequent igniting cycles is selected shorter than that of the first igniting cycle. When an existing combustion control element which is capable of performing the igniting cycle only once is employed, the intended combustion control is performed by appropriately controlling a reset terminal of the existing combustion control element of signals representative of expirations of the pre-purge time interval and the ignition time interval. The number of the igniting cycles is counted by a counter for stopping operation of the combustion apparatus when a predetermined count value is attained. A novel circuit for the combustion control element is also disclosed.

Abstract: There is disclosed an igniting and flame detecting device of one rod type having an electrode used for generating a spark for firing gas from a burner and also for supplying an AC voltage for detecting a flame generated by the firing, in which a pulse generating transformer is provided for generating the spark at the electrode with its secondary coil connected in series with the electrode through a discharge tube, a flame detection transformer is provided to apply AC voltage to the flame generated by firing the gas from burner with its secondary coil connected in series with a resistor and a capacitor to form a series circuit which is connected in parallel with the discharge tube, a detection circuit is provided to detect DC voltage component produced, due to rectifying effects of the flame, across the capacitor, and a gap discharge element having a discharge starting voltage which is higher than a normal discharge starting voltage of the discharge tube is connected in parallel with the discharge tube, whereb

Abstract: A combustion control apparatus which controls combustion in a combustor which is a heat source of a hot-water boiler or a hot-air heater includes a memory circuit which generates an alarm signal and also a signal for stopping the operation of the apparatus and which maintains the apparatus in the shutdown state, when an abnormal condition such as abnormal heating or ignition failure is sensed. This memory circuit is protected from malfunction due to noise generated from external output units in the combustion control apparatus by a circuit which detects an abnormality signal with timing other than the timing of generation of noise from the external output units, and the output of this circuit is applied as an input to the memory circuit. The detection circuit is arranged to detect the abnormality signal while receiving clock pulses from a timer as its input, and the phase of its detection timing is selected to be out of phase with the noise generation.

Abstract: This invention relates to a control circuit which controls combustion in a burner acting as a heat source of a hot-water boiler or a hot-air heater. More particularly, the present invention relates to a control circuit having a sequence which includes post-discharge such that electric discharge for ignition is still continued for a predetermined period of time, even after attainment of ignition. In a combustion control apparatus, when ignition is not attained within a predetermined safty period, the igniting operation is stopped by a safty timer for timing this safety period, thereby ensuring the safety. It is necessary to reliably discontinue the igniting operatin even when this safety timer is disabled. The present invention attains this object and ensures the safety with a reduced number of timers.

Abstract: An electric corrosion preventing apparatus with a circuit having an indication lamp for indicating an operation state of the apparatus, which is used for preventing an inside wall of a hot-water receptacle, such as a water heater and a boiler, from being corroded by rust. In the circuit, the secondary winding of a voltage-dropping transformer is provided with a couple of diode-capacitor combinations. Those diode-capacitor combinations, respectively, are used for rectifying positive and negative parts of a low AC voltage produced by the secondary winding into positive and negative DC voltages. A positive DC voltage is coupled with an electric corrosion prevention load while a negative DC voltage is coupled with a lamp load. With this circuit arrangement, the positive part of the AC voltage is used for the electric corrosion prevention while the negative part, for the lamp.