Universal on-delay timer

Claim 2

A universal on-delay timer system that operates properly on any power supply voltage through a wide range of voltages of either A.C. or D.C. to energize a load a time interval after closure of a pilot switch comprising: an electrical power supply source; a load circuit including power switching means controllable to connect said source to said load; a control circuit comprising a timer circuit including triggering means operable by said timer circuit at the end of a precisely measured time interval; a power conversion circuit fed from said source for providing a control voltage of predetermined value for a wide range of power supply voltages of either A.C. or D.C.; a pilot switch operable to control energization and deenergization of the load; means including said power conversion circuit responsive to closure of said pilot switch for applying said control voltage to operate said timer circuit; means including control switching means responsive to said triggering means at time-out of said timer circuit for operating said power switching means to energize the load at the end of a precisely measured time interval for accurate repeatability; said control switching means including means electrically isolating said control circuit from said load circuit.

Claim 3

The invention defined in claim 1, wherein said pilot switch is effective upon reopening thereof for controlling immediate deenergization of the load.

Claim 4

A universal on-delay timer system that operates properly on any power supply voltage through a wide range of voltages of either A.C. or D.C. to energize a load a time interval after closure of a pilot switch comprising: an electrical power supply source; a load circuit including power switching means controllable to connect said source to said load; a control circuit comprising a timer circuit; a power conversion circuit fed from said source for providing a control voltage of predetermined value for a wide range of power supply voltages of either A.C. or D.C.; a pilot switch operable to control energization and deenergization of the load; means including said power conversion circuit responsive to closure of said pilot switch for applying said control voltage to operate said timer circuit; means including control switching means responsive to time-out of said timer circuit for operating said power switching means to energize the load; said control switching means including means electrically isolating said control circuit from said load circuit; said pilot switch being effective upon reopening thereof for controlling immediate deenergization of the load; said power conversion circuit incorporating: a leaky switch detection circuit comprising: impedance means; and means for detecting the relative impedance of said pilot switch and to allow proper operation under conditions where the closed pilot switch impedance is a predetermined small value or less and where the open pilot switch impedance is a predetermined large value or more, and where the applied voltage may vary over a wide range.

Claim 5

A universal on-delay timer system that operates properly on any power supply voltage through a wide range of voltages of either A.C. or D.C. to energize a load a time interval after closure of a pilot switch comprising: an electrical power supply source; a load circuit including power switching means controllable to connect said source to said load; a control circuit comprising a timer circuit; a power conversion circuit fed from said source for providing a control voltage of predetermined value for a wide range of power supply voltages of either A.C. or D.C.; a pilot switch operable to control energization and deenergization of the load; means including said power conversion circuit responsive to closure of said pilot switch for applying said control voltage to operate said timer circuit; means including control switching means responsive to time-out of said timer circuit for operating said power switching means to energize the load; said control switching means including means electrically isolating said control circuit from said load circuit; said pilot switch being effective upon reopening thereof for controlling immediate deenergization of the load; said power conversion circuit incorporating: a leaky switch detection circuit comprising: impedance means; and means for detecting the relative impedance of said pilot switch and to allow proper operation under conditions where the closed pilot switch impedance is a predetermined small value or less and where the open pilot switch impedance is a predetermined large value or more, and where the applied voltage may vary over a wide range.

Claim 6

The invention defined in claim 3, wherein: said predetermined small impedance value is approximately 100 ohms and said predetermined large value is approximately 40,000 ohms.

Claim 7

A universal on-delay timer system that operates properly on any power supply voltage through a wide range of voltages of either A.C. or D.C. to energize a load a time interval after closure of a pilot switch comprising: an electrical power supply source; a load circuit including power switching means controllable to connect said source to said load; a control circuit comprising a timer circuit; a power conversion circuit fed from said source for providing a control voltage of predetermined value for a wide range of power supply voltages of either A.C. or D.C.; a pilot switch operable to control energization and deenergization of the load; means including said power conversion circuit responsive to closure of said pilot switch for applying said control voltage to operate said timer circuit; means including control switching means responsive to timeout of said timer circuit for operating said power switching means to energize the load; said control switching means including means electrically isolating said control circuit from said load circuit; said control circuit comprising: an indicator circuit fed from said control voltage comprising: a visual indicator that is off when said pilot switch is open; means responsive to closure of said pilot switch to initiate timing for causing said visual indicator to operate in a flashing mode; and means responsive to said control switching means at time-out for terminating said flashing mode and operating said visual indicator in a continuous indication mode.

Claim 8

A universal on-delay timer system that operates properly on any power supply voltage through a wide range of voltages of either A.C. or D.C. to energize a load a time interval after closure of a pilot switch comprising: an electrical power supply source; a load circuit including power switching means controllable to connect said source to said load; a control circuit comprising a timer circuit; a power conversion circuit fed from said source for providing a control voltage of predetermined value for a wide range of power supply voltages of either A.C. or D.C.; a pilot switch operable to control energization and deenergization of the load; means including said power conversion circuit responsive to closure of said pilot switch for applying said control voltage to operate said timer circuit; means including control switching means responsive to timeout of said timer circuit for operating said power switching means to energize the load; said control switching means including means electrically isolating said control circuit from said load circuit; said control circuit comprising: an indicator circuit fed from said control voltage comprising: a visual indicator that is off when said pilot switch is open; means responsive to closure of said pilot switch to initiate timing for causing said visual indicator to operate in a flashing mode; and means responsive to said control switching means at time-out for terminating said flashing mode and operating said visual indicator in a continuous indication mode.

Claim 9

The invention defined in claim 1, wherein said control circuit comprises: semiconductor means for resetting said timer circuit so that each timing cycle is uniform for accurate repeatability; and reset disabling means responsive to closure of said pilot switch for rendering said resetting means ineffective, and being responsive to reopening of said pilot switch for allowing operation of said resetting means.

Claim 10

A universal on-delay timer system that operates properly on any power supply voltage through a wide range of voltages of either A.C. or D.C. to energize a load a time interval after closure of a pilot switch comprising: an electrical power supply source; a load circuit comprising a triac and a pilot switch operable to connect said load circuit to said power supply source and to initiate operation of the system; a control circuit comprising a timer circuit and an indicator circuit; a power conversion circuit fed from said source for providing a regulated unidirectional control voltage of predetermined value for a wide range of power supply voltages above said value and of either A.C. or D.C.; means including said power conversion circuit responsive to to operation of said pilot switch for providing said unidirectional control voltage to said control circuit to initiate operation of sAid timer circuit; a visual indicator and means in said indicator circuit responsive to said unidirectional control voltage while said timer is timing for causing flashing of said visual indicator; and control switching means responsive to time-out of said timer circuit for firing said triac into conduction to energize said load and for continuously energizing said visual indicator.

Claim 11

A universal on-delay timer system that operates properly on any power supply voltage through a wide range of voltages of either A.C. or D.C. to energize a load a time interval after closure of a pilot switch comprising: an electrical power supply source; a load circuit comprising a triac and a pilot switch operable to connect said load circuit to said power supply source and to initiate operation of the system; a control circuit comprising a timer circuit and an indicator circuit; a power conversion circuit fed from said source for providing a regulated unidirectional control voltage of predetermined value for a wide range of power supply voltages above said value and of either A.C. or D.C.; means including said power conversion circuit responsive to to operation of said pilot switch for providing said unidirectional control voltage to said control circuit to initiate operation of sAid timer circuit; a visual indicator and means in said indicator circuit responsive to said unidirectional control voltage while said timer is timing for causing flashing of said visual indicator; and control switching means responsive to time-out of said timer circuit for firing said triac into conduction to energize said load and for continuously energizing said visual indicator.

Claim 12

The invention defined in claim 7, wherein said power conversion circuit incorporates: a leaky switch detector circuit comprising: a detector transistor; means fed from said power supply source for applying a bias voltage to said transistor; means comprising an impedance forming with said pilot switch a voltage divider fed from said power supply source to apply an operating voltage to said transistor in opposition to said bias voltage; and said bias voltage and said impedance being proportional so that said transistor conducts when the closed pilot switch impedance is below a predetermined small value and stops conducting when the open pilot switch impedance is above a predetermined large value.

Claim 13

The invention defined in claim 8, wherein said power conversion circuit also comprises: means comprising an emitter-follower power transistor fed from said power supply source and being responsive to conduction of said detector transistor for providing said unidirectional control voltage.

Claim 14

The invention defined in claim 7, wherein said control switching means comprises: a reed relay for firing said triac into conduction; and a semi-conductor controlled rectifier for energizing said reed relay and for continuously energizing said visual indicator.