Regulator for controlling capacitor charge to provide complex waveform

Abstract

In fuel injection ignition systems, it is necessary to provide control of the open time of the fuel injector valves which varies with the engine speed. However, for efficient operation with a minimum of pollution, the relationship of valve open time to engine speed is not a simple relationship, and factors other than engine speed are involved. It has been found that the open time should change with engine speed by steps not directly related to engine speed. This can be accomplished by providing a waveform which varies with time across a capacitor by a regulator system which controls both increase and decrease of the voltage across the capacitor. This voltage waveform, which varies with time and is independent of engine speed, can then be combined with a ramp voltage initiated at a particular point of rotation of the engine at the time the injector valves are opened. The valves can then be turned off when the combined voltage has the desired relation to a voltage produced by manifold pressure to provide the required open time for the injector valves.

We claim: 
     
       1. A circuit for developing across a capacitor a waveform having a plurality of different voltage levels at least one of which is greater than the preceding level and at least one of which is less than the preceding level, such circuit including in combination, reference means providing a plurality of reference voltages representing the different voltage levels of the waveform, regulator means coupled to said reference means and to the capacitor for selectively holding the voltage thereacross at a value associated with one of the reference voltages, .Iadd.said regulator means including a differential amplifier, .Iaddend.discharge circuit means connected to the capacitor and to said regulator means and adapted to be rendered operative by said regulator means to discharge the capacitor and reduce the voltage thereacross until a selected one of the voltage levels is reached, and current source means connected to the capacitor and adapted to operate to supply current thereto to increase the voltage thereacross until another one of the voltage levels is reached. 
     
     
       2. The circuit of claim 1 further including timing means coupled to said regulator means and to said current source means for rendering the same operative in a predetermined time relation. 
     
     
       3. A circuit in accordance with claim 2 wherein said timing means caues said regulator means to control the voltage across the capacitor at a first level in response to a first reference voltage and thereafter applies a control potential to said regulator means to control the voltage across the capacitor at a second level in response to a second reference voltage. 
     
     
       4. A circuit in accordance with claim 2 wherein said .[.regulator means includes a.]. differential amplifier .Iadd.is .Iaddend.connected to the capacitor and responsive to a voltage on the capacitor above the first voltage level to control said discharge circuit to discharge the capacitor to the first voltage level, said differential amplifier being responsive to a first reference voltage to hold the voltage across the capacitor at the first voltage level, and wherein said timing means deactivates said discharge circuitry to allow said current source to charge the capacitor so that the voltage thereacross increases to a second voltage level, said timing means controlling said regulator means so that said differential amplifier responds to a second reference voltage and operates said discharge circuit to prevent charge of the capacitor above the second voltage level so that the voltage across the capacitor is held at the second voltage level. 
     
     
       5. A circuit in accordance with claim 2 wherein said regulator means includes an emitter follower circuit connected between said reference means and the capacitor and responsive to the voltage on the capacitor, said timing means controlling said regulator means so that said emitter follower circuit responds to a first reference voltage and actuates said discharge circuit means to discharge the capacitor so that the voltage thereacross decreases to the first voltage level, said emitter follower operating to hold the voltage across the capacitor at said first voltage level. 
     
     
       6. A circuit in accordance with claim 2 wherein said regulator means initially responds to a first reference voltage and operates said .[.dischagge.]. .Iadd.discharge .Iaddend.circuit means to cause the capacitor to discharge to a first voltage level related to said first reference voltage, said timing means applying a first control signal to said regulator means to cause the same to operate in response to a second reference voltage and to cause said discharge circuit to discharge the capacitor so that the voltage thereacross drops to a second voltage level related to said second reference voltage, said timing means applying a second control signal to said regulator means to control said discharge circuit so that said current source means charges the capacitor so that the voltage thereacross rises from the second voltage level to a third voltage level, with said regulator means being responsive to a third reference voltage to operate said discharge circuit means so that the voltage across the capacitor does not rise above the third voltage level, and said timing means applying a third control signal to said current source means and to said regulator means to render said current source means inoperative and cause said regulator means to respond to a fourth reference potential and to operate said discharge circuit means to discharge the capacitor so that the voltage thereacross drops from the third voltage level to a fourth voltage level, said regulator means acting to hold the voltage across the capacitor at each voltage level until a further control signal is received. 
     
     
       7. A circuit in accordance with claim 1 wherein said discharge circuit means includes first and second portions selectively coupled to the capacitor for discharging the same, and said regulator means includes first and second portions coupled respectively to said first and second portions of said discharge circuit means, said first portion of said regulator means responding to a first reference voltage to operate said first portion of said discharge circuit means, and said second portion of said regulator means responding to a second reference voltage to operate said second portion of said discharge circuit means. 
     
     
       8. The circuit of claim 1 wherein said current source means is selectively operated to charge the capacitor to provide a voltage ramp superimposed on the voltage waveform thereacross, and further including trigger means coupled to said regulator means and to said current source means for controlling the initiation of the waveform across the capacitor and the initiation of the voltage ramp, and means coupled to the capacitor for providing a control in reponse to the superimposed voltage across the capacitor. 
     
     
       9. A circuit in accordance with claim 8 wherein said current source means includes first and second current supply means selectively connected to said capacitor means, said regulator means includes control means for selectively rendering said regulator means responsive to different ones of said reference voltages, and further including timing means coupled to said regulator means and to said first current supply means, said regulator means being initially responsive to a first reference voltage and operating said discharge circuit means to cause said capacitor means to discharge to a first voltage level related to said first reference voltage, and wherein said timing means applies a first control signal to said control means to cause said regulator means to operate in response to a second reference voltage and to cause said discharge circuit to discharge said capacitor means so that the voltage thereacross drops to a second voltage level related to said second reference voltage, said timing means applying a second control signal to said control means at a time following the first control signal to operate said discharge circuit means so that said first current supply means charges said capacitor means so that the voltage thereacross rises from the second voltage level to a third voltage level, said regulator means being rendered responsive to a third reference voltage to operate said discharge circuit means so that the voltage across said capacitor means does not rise above the third voltage level, and said timing means applying a third control signal to said first current supply means and to said control means at a time following the second control signal to render said first current supply means inoperative and cause said regulator means to respond to a fourth reference potential and to operate said discharge circuit means to discharge said capacitor means so that the voltage thereacross drops from the third voltage level to a fourth voltage level, with the waveform across the capacitor including said first, second, third and fourth voltage levels, and trigger means interrupting the waveform and causing said second current supply means to charge the capacitor to provide the voltage ramp superimposed on the voltage waveform across the capacitor at the time of interruption. 
     
     
       10. A circuit in accordance with claim 9 wherein said .[.regulator means includes a.]. differential amplifier .Iadd.is .Iaddend.connected to said capacitor means and said discharge circuit means includes first and second portions, said differential amplifier being responsive to a voltage on said capacitor means above the first voltage level to control said first portion of said discharge circuit means to discharge said capacitor means to the first voltage level, said differential amplifier being responsive to a first reference voltage to hold the voltage across said capacitor means at the first voltage level, wherein said control means responds to said first control signal from said timing means to cause said regulator means to control said second portion of said discharge circuit means to discharge said capacitor means so that the voltage thereacross drops from said first voltage level to said second voltage level, wherein said control means responds to said second control signal from said timing means to actuate said regulator means so that said differential amplifier responds to said third reference voltage and operates said first portion of said discharge circuit means to prevent further charge of said capacitor means by said first current supply means so that the voltage thereacross does not rise above the third voltage level, and wherein said control means responds to said third control signal from said timing means to cause said first current supply means to be inoperative and to cause said regulator means to control said second portion of said discharge circuit means to discharge said capacitor means so that the voltage thereacross drops from said third voltage level to said fourth voltage level. 
     
     
       11. A circuit for producing a predetermined voltage wave having a plurality of different voltage levels, at least one of which is greater than the preceding level and at least one of which is less than the preceding level, such circuit including in combination, capacitor means, reference means providing a plurality of reference voltage presenting the different voltage levels of the voltage wave, regulator means coupled to said reference voltage and to said capacitor means for selectively holding the voltage thereacross at a value associated with one of the reference voltages, .Iadd.said regulator means including a differential amplifer, .Iaddend.current source means connected to said capacitor means to supply current to said capacitor means to charge the same, and discharge circuit means connected to said capacitor means and to said regulator means and adapted to be rendered operative by said regulator means to discharge said capacitor means and to reduce the voltage thereacross until a selected one of said different voltage levels is reached, said discharge circuit means being controlled so that said current source means charges said capacitor means to increase the voltage thereacross until another one of the voltage levels, which is greater than the preceding level, is reached. 
     
     
       12. The circuit of claim 11 wherein said regulator means includes control means for selectively rendering the same responsive to different ones of said reference voltages, and said regulator means is operative to hold the voltage across said capacitor means at a value related to one of said reference voltages until said control means operates to render said regulator means responsive to a different reference voltage. 
     
     
       13. A circuit in accordance with claim 11 wherein said regulator means includes control means for selectively rendering the same responsive to different ones of said reference voltage, said regulator means being initially responsive to a first reference voltage and operating said discharge circuit means to cause said capacitor means to discharge to a first voltage level related to said first reference voltage, and further including timing means coupled to said control means and to said current source means, said timing means applying a first control signal to said control means to cause said regulator means to operate in response to a second reference voltage and to cause said discharge circuit means to discharge said capacitor means so that the voltage thereacross drops to a second voltage level related to said second reference voltage, said timing means applying a second control signal to said control means to control said discharge circuit means so that said current source means charges said capacitor means so that the voltage thereacross rises from the second voltage level to a third voltage level, said regulator means being rendered responsive to a third reference voltage to operate said discharge circuit means so that the voltage across said capacitor means does not rise above the third voltage level, and said timing means applying a third control signal to said current source means and to said regulator means to render said current source inoperative, and to cause said regulator means to respond to a fourth reference potential and to operate said discharge circuit means to discharge said capacitor means so that the voltage thereacross drops from the third voltage level to a fourth voltage level. 
     
     
       14. A circuit in accordance with claim 13 wherein said discharge circuit means includes a first portion which causes said capacitor means to discharge to said first voltage level and which operates to prevent the voltage across said capacitor means from rising above said third voltage level, and a second portion which causes said capacitor means to discharge so that the voltage thereacross drops from said first voltage level to said second voltage level and to discharge so that the voltage thereacross drops from said third voltage level to said fourth voltage level. 
     
     
       15. A circuit in accordance with claim 13 wherein said .[.regulator means includes a.]. differential amplifier .Iadd.is .Iaddend.connected to said capacitor means and responsive to a voltage on said capacitor means above the first voltage level to control said discharge circuit means to discharge said capacitor means to the first voltage level, said differential amplifier being responsive to a first reference voltage to hold the voltage across said capacitor means at the first voltage level, and wherein said second control signal from said timing means actuates said regulator means so that said differential amplifier responds to said third reference voltage and operates said discharge circuit means to prevent charge of said capacitor means by said current source means so that the voltage thereacross rises above the third voltage level, whereby the voltage across said capacitor means is held at the third voltage level. 
     
     
       16. The circuit of claim 13 wherein said capacitor means includes first and second capacitors and wherein said regulator means, said discharge circuit means and said current source means are selectively coupled to said first capacitor to provide the voltage wave thereacross during a first cycle, and are connected to said second capacitor to provide the voltage wave thereacross during a second cycle. 
     
     
       17. A circuit in accordance with claim 16 further including ramp current means and means for selectively coupling said ramp current means to said first and second capacitors to provide a ramp voltage superimposed on the voltage wave across said first capacitor during the second cycle, and to provide a ramp voltage superimposed on the voltage wave across said second capacitor during a third cycle. .Iadd. 18. A circuit in accordance with claim 1 wherein said regulator means includes: current supply means;   said differential amplifier having differentially connected first and second electron control means each having first, second and control electrodes, said first and second electron control means having commonly connected first electrodes which are coupled to said current supply means; and   differential-to-single ended converter means coupled between said second electrodes of said differentially connected first and second electron control means, and said discharge circuit means. .Iaddend..Iadd. 19. A circuit in accordance with claim 18 wherein said first and second electron control means each include at least one transistor. .Iaddend. .Iadd. 20. A circuit in accordance with claim 18 further having a selecting circuit for controlling which of a plurality of reference voltages of different potentials is applied to the control electrode of one of said differentially connected electron control means, the selecting circuit including:   first transistor means having a control electrode adapted to receive one of the reference voltages, a first electrode connected to said control electrode of said one of said differentially connected electron control means, and a second electrode coupled to receive a predetermined power supply potential; and   second transistor means having a control electrode adapted to receive another of the reference potentials, a first electrode coupled to said control electrode of said one of said differentially connected transistors, and a second electrode coupled to receive the predetermined power supply potential, only the one of the first and second transistor means receiving the reference voltage of the lowest magnitude being rendered conductive so that the regulator means is responsive to only the reference voltage having the lowest potential. .Iaddend. .Iadd. 21. A circuit in accordance with claim 1, wherein said regulator means further includes in combination;   first transistor means of a first conductivity type having first, second and control electrodes, said control electrode being coupled to the reference means, said second electrode being connected to receive a power supply potential;   current supply means coupled to said first electrode of said first transistor means, said first transistor means developing an intermediate voltage at said first electrode thereof having a magnitude with a predetermined relation to the reference magnitude provided at the control electrode thereof; and   second transistor means of a second conductivity type having control, first and second electrodes, said control electrode of said second transistor means being coupled to said first electrode of said first transistor means, said second electrode of said second transistor means being adapted to receive a power supply potential and said first electrode of said second transistor means being coupled to the capacitor, said second transistor substantially returning the intermediate voltage back to the reference level at said first electrode thereof so that the reference level can be coupled to the capacitor. .Iaddend. .Iadd. 22. A circuit in accordance with claim 21 wherein:   said first transistor means includes a bipolar transistor having emitter, base and collector electrodes, respectively corresponding to said first, control and second electrodes, and said intermediate voltage differs from said referenced voltage by the base-to-emitter voltage drop of said bipolar transistor; and   said second transistor means includes a further bipolar transistor having emitter, base and collector electrodes, respectively corresponding to said, first, control and second electrodes thereof, said emitter-to-base junction of said further bipolar transistor substantially returning the intermediate voltage back to the reference level. .Iaddend. .Iadd. 23. A circuit in accordance with claim 1, wherein said discharge circuit means includes a current supply means comprising:   first transistor means of a first conductivity type having first, second and control electrodes, said control electrode being coupled to receive a bias voltage, said second electrode being connected to receive a power supply potential;   current supply means providing an unregulated current;   circuit means coupling said current supply means to said first electrode of said first transistor means, said first transistor means developing an intermediate voltage at said first electrode thereof having the magnitude of a predetermined relation to said bias voltage provided at the control electrode thereof in response to said unregulated current from said current supply;   second transistor means of a second conductivity type having control, first and second electrodes, said control electrode of said second transistor means being coupled to said first electrode of said first transistor means; and   resistive means coupling said first electrode of said second transistor means to a power supply conductor, said second electrode of said second transistor means being adapted to provide a regulated current having a magnitude which is much more constant than said unregulated current provide by said current supply means, said regulated current enabling the capacitor to be discharged at a predetermined constant rate. .Iaddend. .Iadd. 24. A circuit in accordance with claim 23, wherein:   said first transistor means includes a bipolar transistor having emitter, base and collector electrodes respectively corresponding to said first, control and second electrodes, and said intermediate voltage differs from said bias voltage by the base-to-emitter voltage drop of said bipolar transistor; and   said second transistor means includes a further bipolar transistor having emitter, base and collector electrodes respectively corresponding to said first, control and second electrodes, said emitter-to-base junction of said further bipolar transistor returning the intermediate voltage substantially to the reference level applied to the base electrode of the first transistor means so that said regulated current developed at the collector electrode of said second transistor means is precisely controlled. .Iaddend..Iadd. 25. A circuit in accordance with claim 23 wherein said circuit means includes a switch means for enabling and disabling the current supply means. .Iaddend. .Iadd. 26. A circuit in accordance with claim 4 wherein said differential amplifier further includes:   current supply means;   differentially connected first and second electron control means each having first, second and control electrodes, said first and second electron control means having commonly connected first electrodes which are coupled to said current supply means; and   differential-to-single ended converter means coupled between said second electrodes of said differentially connected first and second electron control means, and said discharge circuit means. .Iaddend..Iadd. 27. A circuit in accordance with claim 26 wherein said first and second electron control means each include at least one transistor. .Iaddend. .Iadd. 28. A circuit in accordance with claim 26 further having a selecting circuit for controlling which of a plurality of reference voltages of different potentials is applied to the control electrode of one of said differentially connected electron control means, the selecting circuit including in combination:   first transistor means having a control electrode adapted to receive one of the reference voltages, a first electrode connected to said control electrode of said one of said differentially connected electron control means, and a second electrode coupled to receive a predetermined power supply potential; and   second transistor means having a control electrode adapted to receive another of the reference potentials, a first electrode coupled to said control electrode of said one of said differentially connected transistors, and a second electrode coupled to receive the predetermined power supply potential, only the one of the first and second transistor means receiving the reference voltage of the lowest magnitude being rendered conductive so that the regulator means is responsive to only the reference voltage having the lowest potential. .Iaddend..Iadd. 29. A circuit in accordance with claim 28 further including:   circuit means connected to said reference means for selectively elevating some of the reference levels so that another of the reference levels is applied to said differential amplifier by said selecting circuit. .Iaddend. .Iadd. 30. A circuit in accordance with claim 5 wherein said emitter follower circuit includes in combination:   first transistor means of a first conductivity type having first, second and control electrodes, said control electrode being coupled to the reference means, said second electrode being connected to receive a power supply potential;   current supply means coupled to said first electrode of said first transistor means, said first transistor means developing an intermediate voltage at said first electrode thereof having a magnitude with a predetermined relation to the reference voltage provided at the control electrode thereof; and   second transistor means of a second conductivity type having control, first and second electrodes, said control electrode of said second transistor means being coupled to said first electrode of said first transistor means, said second electrode of said second transistor means being adapted to receive a power supply potential and said first electrode of said second transistor means being coupled to the capacitor, said second transistor substantially returning the intermediate voltage back to the reference level at said first electrode thereof so that the reference level can be selectively coupled to the capacitor. .Iaddend. .Iadd. 31. An emitter follower circuit in accordance with claim 30 wherein:   said first transistor means includes a bipolar transistor having emitter, base and collector electrodes, respectively corresponding to said first, control and second electrodes, and said intermediate voltage differs from said reference voltage by the base-to-emitter voltage drop of said bipolar transistor; and   said second transistor means includes a further bipolar transistor having emitter, base and collector electrodes, respectively corresponding to said, first, control and second electrodes thereof, said emitter-to-base junction of said further bipolar transistor substantially returning the intermediate voltage back to the reference level. .Iaddend. .Iadd. 32. A circuit in accordance with claim 6 wherein the regulator means further includes:   first and second differential regulator circuits, each of said differential regulator circuits having current supply means, differentially connected first and second transistor means each having first, second and control electrodes, said first and second transistor means having commonly connected first electrodes which are coupled to said current supply means, differential-to-single ended converter means coupled between said second electrodes of said differentially connected first and second transistor means, and said discharge circuit means, and   first and second emitter follower regulator circuits, each of said emitter follower regulator circuits having third transistor means of a first conductivity type having first, second and control electrodes, said control electrode being coupled to the reference means, said second electrode being connected to receive a power supply potential; current supply means coupled to said first electrode of said third transistor means, said third transistor means developing an intermediate voltage at said first electrode thereof having a magnitude with a predetermined relation to the reference magnitude provided at the control electrode thereof; and fourth transistor means of a second conductivity type having control, first and second electrodes, said control electrode of said fourth transistor means being coupled to said first electrode of said third transistor means, said second electrode of said fourth transistor means being adapted to receive a power supply potential and said first electrode of said fourth transistor means being coupled to the capacitor, said fourth transistor substantially returning the intermediate voltage back to the reference level at said first electrode thereof so that the reference level can be coupled to the capacitor. .Iaddend..Iadd. 33. A circuit in accordance with claim 32 further having a selecting circuit for controlling which of a plurality of reference voltages of different potentials is applied to the control electrode of one of said differentially connected transistor means of each of said differential voltage regulator circuit the selecting circuit including:   fifth means having a control electrode adapted to receive one of the reference voltages, a first electrode connected to said control electrode of said one of said differentially connected transistor means, and a second electrode coupled to receive a predetermined power supply potential; and   sixth transistor means having a control electrode adapted to receive another of the reference potentials, a first electrode coupled to said control electrode of said one of said differentially connected transistors, and a second electrode coupled to receive the predetermined power supply potential, only the one of the fifth and sixth transistor means receiving the reference voltage of the lowest magnitude being rendered conductive so that each differential regulator means is responsive to only the reference voltage having the lowest potential. .Iaddend. .Iadd. 34. A circuit in accordance with claim 7, wherein said second portion of said discharge circuit means includes a current supply means comprising:   first transistor means of a first conductivity type having first, second and control electrodes, said control electrode being coupled to receive a bias voltage, said second electrode being connected to receive a power supply potential;   current supply means providing an unregulated current;   circuit means coupling said current supply means to said first electrode of said first transistor means, said first transistor means developing an intermediate voltage at said first electrode thereof having the magnitude of a predetermined relation to said bias voltage provided at the control electrode thereof in response to said unregulated current from said current supply;   second transistor means of a second conductivity type having control, first and second electrodes, said control electrode of said second transistor means being coupled to said first electrode of said first transistor means; and   resistive means coupling said first electrode of said second transistor means to a power supply conductor, said second electrode of said second transistor means being adapted to provide a regulated current having a magnitude which is more constant than said unregulated current provided by said current supply means, said regulated current enabling the capacitor to be discharged at a predetermined constant rate. .Iaddend. .Iadd. 35. A circuit in accordance with claim 34, wherein:   said first transistor means includes a bipolar transistor having emitter, base and collector electrodes respectively corresponding to said first, control and second electrodes, and said intermediate voltage differs from said bias voltage by the base-to-emitter voltage drop of said bipolar transistor; and   said second transistor means includes a further bipolar transistor having emitter, base and collector electrodes respectively corresponding to said first, control and second electrodes, said emitter-to-base junction of said further bipolar transistor returning the intermediate voltage substantially to the reference level applied to the base electrode of the first transistor means so that said regulated current developed at the collector electrode of said second transistor means is precisely controlled. .Iaddend..Iadd. 36. A circuit in accordance with claim 35, wherein said circuit means includes a switchable electron control means for enabling and disabling the current supply means. .Iaddend. .Iadd. 37. A circuit in accordance with claim 7 wherein said first portion of said regulator means includes:   current supply means;   differentially connected first and second transistor means each having first, second and control electrodes, said first and second transistor means having commonly connected first electrodes which are coupled to said current supply means; and   differential-to-single ended converter means coupled between said second electrodes of said differentially connected first and second transistor means, and said discharge circuit means. .Iaddend. .Iadd. 38. A circuit in accordance with claim 7, wherein said second regulator means further includes in combination:   first transistor means of a first conductivity type having first, second and control electrodes, said control electrode being coupled to the reference means, said second electrode being connected to receive a power supply potential;   current supply means coupled to said first electrode of said first transistor means, said first transistor means developing an intermediate voltage at said first electrode thereof having a magnitude with a predetermined relation to the reference magnitude provided at the control electrode thereof; and   second transistor means of a second conductivity type having control, first and second electrodes, said control electrode of said second transistor means being coupled to said first electrode of said first transistor means, said second electrode of said second transistor means being adapted to receive a power supply potential and said first electrode of said second transistor means being coupled to the capacitor, said second transistor substantially returning the intermediate voltage back to the reference level at said first electrode thereof so that the reference level can be coupled to the capacitor. .Iaddend. .Iadd. 39. A circuit in accordance with claim 11 wherein said regulator means includes:   current supply means;   said differential amplifier having first and second transistor means each having first, second and control electrodes, said first and second transistor means being differentially coupled with each other, said first and second transistor means having commonly connected first electrodes which are coupled to said current supply means; and   differential-to-single ended converter means coupled between said second electrodes of said differentially connected first and second transistor means, and said discharge circuit means. .Iaddend. .Iadd. 40. A circuit in accordance with claim 39 further having a selecting circuit for controlling which of a plurality of reference voltages of different potentials is applied to the control electrode of one of said differentially connected transistor means, the selecting circuit including:   third transistor means having a control electrode adapted to receive one of the reference voltages, a first electrode connected to said control electrode of said one of said differentially connected transistor means, and a second electrode coupled to receive a power supply potential; and   fourth transistor means having a control electrode adapted to receive another of the reference potentials, a first electrode coupled to said control electrode of said one of said differentially connected transistors, and a second electrode coupled to receive the power supply potential, only the one of said third and fourth transistor means receiving the reference voltage of the lowest magnitude being rendered conductive so that the regulator means is responsive to only the reference voltage having the lowest potential. .Iaddend. .Iadd. 41. A circuit in accordance with claim 39, wherein said regulator means further includes in combination:   third transistor means of a first conductivity type having first, second and control electrodes, said control electrode being coupled to the reference means, said second electrode being connected to receive a power supply potential;   current supply means coupled to said first electrode of said third transistor means, said third transistor means developing an intermediate voltage at said first electrode thereof having a magnitude with a predetermined relation to the reference magnitude provided at the control electrode thereof; and   fourth transistor means of a second conductivity type having control, first and second electrodes, said control electrode of said fourth transistor means being coupled to said first electrode of said third transistor means, said second electrode of said fourth transistor means being adapted to receive a power supply potential and said first electrode of said fourth transistor means being coupled to the capacitor, said fourth transistor substantially returning the intermediate voltage back to the reference level at said first electrode thereof so that the reference level can be coupled to the capacitor. .Iaddend. .Iadd. 42. A circuit in accordance with claim 41 wherein:   said third transistor means includes a bipolar transistor having emitter, base and collector electrodes, respectively corresponding to said first, control and second electrodes, and said intermediate voltage differs from said reference voltage by the base-to-emitter voltage drop of said bipolar transistor; and   said fourth transistor means includes a further bipolar transistor having emitter, base and collector electrodes, respectively corresponding to said, first, control and second electrodes thereof, said emitter-to-base junction of said further bipolar transistor substantially returning the intermediate voltage back to the reference level. .Iaddend. .Iadd. 43. A circuit in accordance with claim 11, wherein said discharge circuit means includes a current supply means comprising:   first transistor means of a first conductivity type having first, second and control electrodes, said control electrode being coupled to receive a bias voltage, said second electrode being connected to receive a power supply potential;   current supply means providing an unregulated current;   circuit means coupling said current supply means to said first electrode of said first transistor means, said first transistor means developing an intermediate voltage at said first electrode thereof having the magnitude of a predetermined relation to said bias voltage provided at the control electrode thereof in response to said unregulated current from said current supply;   second transistor means of a second conductivity type having control, first and second electrodes, said control electrode of said second transistor means being coupled to said first electrode of said first transistor means; and   resistive means coupling said first electrode of said second transistor means to a power supply conductor, said second electrode of said second transistor means being adapted to provide a regulated current having a magnitude which is much more constant than said unregulated current provide by said current supply means, said regulated current enabling the capacitor to be discharged at a predetermined constant rate. .Iaddend. .Iadd. 44. A circuit in accordance with claim 13 wherein said regulator means further includes:   first and second differential regulator circuits, each of said differential regulator circuits having current supply means, differentially connected first and second transistor means each having first, second and control electrodes, said first and second transistor means having commonly connected first electrodes which are coupled to said current supply means, differential-to-single ended converter means coupled between said second electrodes of said differentially connected first and second transistor means, and said discharge circuit means, and   first and second emitter follower regulator circuits, each of said emitter follower regulator circuits having third transistor means having first, second and control electrodes, said control electrode being coupled to the reference means, said second electrode being connected to receive a power supply potential; current supply means coupled to said first electrode of said third transistor means, said third transistor means developing an intermediate voltage at said first electrode thereof having a magnitude with a predetermined relation to the reference magnitude provided at the control electrode thereof; and fourth transistor means of a conductivity type opposite to the conductivity type of said third transistor means and having control, first and second electrodes, said control electrode of said fourth transistor means being coupled to said first electrode of said third transistor means, said second electrode of said fourth transistor means being adapted to receive a power supply potential and said first electrode of said fourth transistor means being coupled to the capacitor means, said fourth transistor substantially returning the intermediate voltage back to the reference level at said first electrode thereof so that the reference level can be coupled to the capacitor means. .Iaddend..Iadd. 45. A circuit in accordance with claim 44 further having a selecting circuit for controlling which of a plurality of reference voltages of different potentials is applied to the control electrode of one of said differentially connected transistor means of each of said differential voltage regulator circuit the selecting circuit including:   fifth means having a control electrode adapted to receive one of the reference voltages, a first electrode connected to said control electrode of said one of said differentially connected transistor means, and a second electrode coupled to receive a predetermined power supply potential; and   sixth transistor means having a control electrode adapted to receive another of the reference potentials, a first electrode coupled to said control electrode of said one of said differentially connected transistors, and a second electrode coupled to receive the predetermined power supply potential, only the one of the fifth and sixth transistor means receiving the reference voltage of the lowest magnitude being rendered conductive so that each differential regulator means is responsive to only the reference voltage having the lowest potential. .Iaddend. .Iadd. 46. A circuit in accordance with claim 14, wherein one of said portions of said discharge circuit means includes a current supply means comprising:   first transistor means of a first conductivity type having first, second and control electrodes, said control electrode being coupled to receive a bias voltage, said second electrode being connected to receive a power supply potential;   current supply means providing an unregulated current;   circuit means coupling said current supply means to said first electrode of said first transistor means, said first transistor means developing an intermediate voltage at said first electrode thereof having the magnitude of a predetermined relation to said bias voltage provided at the control electrode thereof in response to said unregulated current from said current supply;   second transistor means of a second conductivity type having control, first and second electrodes, said control electrode of said second transistor means being coupled to said first electrode of said first transistor means; and   resistive means coupling said first electrode of said second transistor means to a power supply conductor, said second electrode of said second transistor means being adapted to provide a regulated current having a magnitude which is more constant than said unregulated current provided by said current supply means, said regulated current enabling the capacitor to be discharged at a predetermined constant rate. .Iaddend. .Iadd. 47. A circuit in accordance with claim 46, wherein:   said first transistor means includes a bipolar transistor having emitter, base and collector electrodes respectively corresponding to said first, control and second electrodes, and said intermediate voltage differs from said bias voltage by the base-to-emitter voltage drop of said bipolar transistor; and   said second transistor means includes a further bipolar transistor having emitter, base and collector electrodes respectively corresponding to said first, control and second electrodes, said emitter-to-base junction of said further bipolar transistor returning the intermediate voltage substantially to the reference level applied to the base electrode of the first transistor means so that said regulated current developed at the collector electrode of said second transistor means is precisely controlled. .Iaddend..Iadd. 48. A circuit in accordance with claim 47, wherein said circuit means includes a switchable electron control means for enabling and disabling the current supply means. .Iaddend. .Iadd. 49. A circuit suitable for being manufactured in monolithic integrated circuit form and for developing a waveform having a plurality of different voltage levels at least one of which is greater than a preceding level and at least one of which is less than a preceding level across a capacitive load external to the monolithic chip, such circuit being adapted to operate in cooperation with a plurality of reference voltages representing the different voltage levels of the waveform and including in combination:   first voltage regulator means having a differential amplifier with an input terminal and an output terminal, said input terminal being connected to receive a first reference voltage related to one of the voltage levels of the waveform and said output terminal being coupled to the capacitive load, said first voltage regulator means tending to prevent the voltage across the capacitive load from rising above a predetermined voltage which is related to said first reference voltage to facilitate the generation of one level of the waveform; and   second voltage regulator means including an emitter follower circuit having an input terminal and an output terminal, said input terminal being coupled to receive a second of the reference voltages, said output terminal being coupled to said capacitive load, said second voltage regulator means tending to prevent the capacitive load from discharging below a voltage level which is related to the second reference voltage to facilitate the generation of another level of said waveform. .Iaddend. .Iadd. 50. A circuit in accordance with claim 49, wherein said first voltage regulator means further includes:   first current supply means;   differentially connected first and second transistor means, each having first, second and control electrodes, said first and second transistor means having commonly connected first electrodes which are coupled to said current supply means;   differential-to-single ended converter means for providing a regulated output voltage being coupled between said second electrodes of said differentially connected first and second electron control means; and   selecting circuit means for controlling which of the plurality of reference voltages of different potentials is applied to the control electrode of one of said differentially connected transistor means, the selecting circuit including third transistor means having a control electrode adapted to receive one of the reference voltages, a first electrode connected to said control electrode of said one of said differentially connected transistor means, and a second electrode coupled to receive a predetermined power supply potential; and fourth transistor means having a control electrode adapted to receive another of the reference potentials, a first electrode coupled to said control electrode of said one of said differentially connected transistor means, and a second electrode coupled to receive the predetermined power supply potential, only the one of the third and fourth transistor means receiving the reference voltage of the lowest magnitude being rendered conductive so that the differentially connected first and second transistor means is responsive to only the reference voltage having the lowest potential. .Iaddend. .Iadd. 51. A circuit in accordance with claim 49, wherein said emitter follower circuit includes in combination:   first transistor means of a first conductivity type having first, second and control electrodes, said control electrode being coupled to the reference circuit for receiving another reference potential, said second electrode being connected to receive a power supply potential;   second current supply means coupled to said first electrode of said first transistor means, said first transistor means developing an intermediate voltage at said first electrode thereof having a magnitude with a predetermined relation to said other reference magnitude provided at the control electrode thereof; and   second transistor means of a second conductivity type having control, first and second electrodes, said control electrode of said second transistor means being coupled to said first electrode of said second transistor means, said second electrode of said fifth transistor means being adapted to receive a power supply potential and said first electrode of said second transistor means being coupled to the capacitor, said second transistor means substantially returning the intermediate voltage back to the reference level at said first electrode thereof. .Iaddend.