Solid state timer circuit for controlling the energization time of a load

Claim 2

An electronic timer for controlling the time period during which a load is energized from an alternating current power source comprising first storage capacitor means, switch means operable when closed to complete a circuit from said power source to cause said first storage capacitor means to charge from said power source to a first charge potential, oscillator means operable in response to the charging of said first storage capacitor means in excess of an oscillator activation potential to provide a pulse output signal, said oscillator means being operable for a period beginning when the charge on said first storage capacitor means exceeds said oscillator activation potential until said charge again passes through said oscillator activation potential, clamping circuit means connected to clamp said oscillator means in an inactive state when the charge on said first storage capacitor means does Not exceed said oscillator activation potential, variable control means connected to control the duration of time required for the charge on said first storage capacitor means to vary from said first charge potential to said oscillator activation potential, and semiconductor switch means connected to control the energization of said load by said power source, said semiconductor switch means being connected to receive said pulse output signal and operating in response thereto to permit energization of said load.

Claim 3

The electronic timer of claim 1 wherein said oscillator means includes a relaxation oscillator including a second capacitor means of less capacity than said first storage capacitor means, said second capacitor means being connected to charge when the charge on said first storage capacitor means exceeds said oscillator activation potential to a potential sufficient to cause said relaxation oscillator to operate.

Claim 4

The electronic timer of claim 2 wherein said switch means and first storage capacitor means are connected in series across said alternating current power source.

Claim 5

The electronic timer of claim 3 wherein said semiconductor switch means includes a Triac connected in series with said load across said alternating current power source, said Triac including a gate electrode connected to receive the pulse output signal from said relaxation oscillator.

Claim 6

The electronic timer of claim 4 wherein said relaxation oscillator includes a Diac trigger diode connected to discharge said second capacitor means to provide the pulse output signal to said Triac gate electrode.

Claim 7

The electronic timer of claim 5 wherein said variable control means includes a variable resistor.

Claim 8

The electronic timer of claim 1 wherein said clamping circuit means operates to reverse charge said first storage capacitor means from said first charge potential through said oscillator activation potential when said switch means is opened subsequent to the charging of said first storage capacitor means to said first potential and constant voltage means is connected to provide a constant voltage to said oscillator means during the reverse charging of said first storage capacitor means until said clamping means is activated by the charge on said first storage capacitor means passing through said oscillator activation potential.

Claim 9

The electronic timer of claim 7 wherein said oscillator means includes a relaxation oscillator having a second capacitor means of less capacity than said first storage capacitor means and a Diac trigger diode connected to discharge said second capacitor means to provide said pulse output signal, said second capacitor means being connected to charge during the period that the charge on said first storage capacitor means is between said first potential and said oscillator activation potential, said clamping circuit means including a semiconductor means connected between said second capacitor means and said Diac trigger diode and operative when conductive to prevent operating voltage from operating said relaxation oscillator, and bias circuit means connected to cause conduction of said semiconductor means when said switching means is open and to prevent conduction of said semiconductor means when the charge on said first storage capacitor means exceeds said oscillator activation potential.

Claim 10

The electronic timer of claim 8 wherein said variable control means includes a variable resistor in said bias circuit means, said bias circuit means being connected to said first storage capacitor means to provide the reverse charging thereof.

Claim 11

An electronic timer for controlling the time period during which a load is energized from an alternating current power source comprising first storage capacitor means, means operable to complete a circuit from said power source for a time sufficient to cause said first storage capacitor means to charge from said power source to a first charge potential, semiconductor switch means connected to control the eNergization of said load by said power source, said semiconductor switch means being connected to receive a pulse output signal and operating in response thereto to permit energization of said load, and oscillator means operable in response to the charging of said first storage capacitor means in excess of an oscillator activation potential which is less than said first charge potential to provide a pulse output signal, said oscillator means being operable for a period beginning when the charge on said first storage capacitor means reaches said oscillator activation potential and including a second capacitor means of less capacity then said first storage capacitor means connected to charge from said first storage capacitor means during the period that the charge on said first storage capacitor means exceeds said oscillator activation potential and discharge means connected to repeatedly discharge said second capacitor means to provide said pulse output signal to said semiconductor switch means, said discharge means operating to discharge said second capacitor means when the charge potential thereon is sufficient to cause the operation of said semiconductor switch means.

Claim 12

An electronic timer for controlling the time period during which a load is energized from an alternating current power source comprising first storage capacitor means, means operable to complete a circuit from said power source for a time sufficient to cause said first storage capacitor means to charge from said power source to a first charge potential, semiconductor switch means connected to control the eNergization of said load by said power source, said semiconductor switch means being connected to receive a pulse output signal and operating in response thereto to permit energization of said load, and oscillator means operable in response to the charging of said first storage capacitor means in excess of an oscillator activation potential which is less than said first charge potential to provide a pulse output signal, said oscillator means being operable for a period beginning when the charge on said first storage capacitor means reaches said oscillator activation potential and including a second capacitor means of less capacity then said first storage capacitor means connected to charge from said first storage capacitor means during the period that the charge on said first storage capacitor means exceeds said oscillator activation potential and discharge means connected to repeatedly discharge said second capacitor means to provide said pulse output signal to said semiconductor switch means, said discharge means operating to discharge said second capacitor means when the charge potential thereon is sufficient to cause the operation of said semiconductor switch means.

Claim 13

The electronic timer of claim 10 wherein said semiconductor switch means includes a gate electrode connected to receive the pulse output signal from said oscillator means, said semiconductor switch means operating to permit energization of said load in response to pulse output signals of a potential which at least equals a gate potential required to initiate conduction of said semiconductor switch means, said second capacitor means operating to charge to a potential which is at last equal to said gate potential when the charge potential on said first storage capacitor means exceeds said oscillator activation potential and said discharge means operates to discharge said second capacitor means when the charge potential thereon is at least equal to said gate potential.

Claim 14

The electronic timer of claim 11 which includes variable control means connected to control the duration of time required for the charge on said first storage capacitor means to vary from said first charge potential to said oscillator activation potential.