Control circuit and fuel burner incorporating a control circuit
AssigneeBritish Gas Corporation
InventorGregory E. Jones
Life of this patent
Estimating the term…
Abstract
A fail-safe supervisory circuit for a microprocessor-controlled fuel burner has a diode pump circuit (C4, C5, D7, D8) triggered by a resettable monostable (R7, T2, R8, C3) responsive to an encoded signal from the microprocessor, to act as a watch-dog timer. A triggered bistable (D1, T1, R2, IC8) provides a RESET signal on power-on or manually. A direct connection from this bistable to the monostable enables the timer circuit until the microprocessor program commences.
Claims5
A fail-safe supervisory system for a control computer which generates repetitively a set of predetermined signals indicative of computer operation, comprising:
- first input means responsive to the set of signals repetitively generated by said computer to produce trigger pulses based thereon;
- resettable monostable circuit means responsive to said trigger pulses for producing an alternating signal when the frequency of said trigger pulses is below a first predetermined level;
- and
- diode pump circuit means responsive to said alternating signal for producing an output signal coupled to said computer and allowing the computer to operate when the frequency of the alternating signal is above a second predetermined level lower than said first predetermined level.
A fail-safe supervisory system for a control computer which generates repetitively a set of predetermined signals indicative of computer operation, comprising:
- first input means responsive to the set of signals repetitively generated by the computer to produce trigger pulses based thereon;
- resettable monostable circuit means responsive to said trigger pulses for producing an alternating signal when the frequency of the trigger pulses is below a first predetermined level;
- diode pump circuit means responsive to said alternating signal for producing an output signal coupled to said computer and allowing the computer to operate when the frequency of the alternating signal is above a second predetermined level which is lower than said first predetermined level;
- and
- bistable circuit means connected to a power supply for said computer to produce an output signal in response to a drop in power supply voltage, said output signal of said bistable circuit means activating a reset of the computer.
Dependencies are inferred from the claim text.