LAMP CONTROL CIRCUIT

• US 3,803,452 A
• Filed: 01/20/1972
• Issued: 04/09/1974
• Est. Priority Date: 01/20/1972
• Status: Expired due to Term

• Current Assignee: Sandor Farkas Goldschmied
• Original Assignee: Sandor Farkas Goldschmied
• Inventors: Goldschmied, Sandor Farkas
• Primary Examiner(s): Saalbach, Herman Karl
• Assistant Examiner(s): Dahl, Lawrence J.
• Application Number:
  US05/219,478
• Time in Patent Office: 810 Days
• Field of Search: 307/252B 315/DIG.4,DIG.5,DIG.7,2A,2R,210,227,240,241
• US Class Current: 315/210
• CPC Class Codes: H05B 41/30 in which the lamp is fed by pulses, e.g. flash lamp
• CPC Class Codes: H05B 41/44 for providing special optical effects, e.g. progressive motion of light
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: Y10S 315/04 Dimming circuit for fluorescent lamps

Abstract

A lamp control circuit useful as a lamp flasher, dimmer or timer and to obtain stroboscopic or other unusual lighting effects. The circuit includes a switch which alternates between two stable states with the dwell time in each state established by a respective interval timing circuit. Power from an ac source is supplied to the lamp by a controlled rectified gated via one of two diacs. The first diac conducts when the voltage across a first capacitor, charged from the ac source, exceeds a certain level and when the switch is in one state. When the switch is in the other state, a discharge circuit maintains the capacitor charge below the diac threshold level. During this time, however, the second diac can gate on the rectifier when the voltage across an associated capacitor, charged from an adjustable voltage source, is sufficiently great. In a flasher mode the switch continuously alternates between states, the circuit providing separate control of the lamp bright and dim time interval and of the dim light intensity. Unusual lighting effects are obtained when the switch dwell time in each state is less than the ac source period.

Claims

1. A lamp control circuit comprising:

a controlled rectifier connecting an ac power source to said lamp, switch means alternating between first and second stable states, a first gating circuit including a first capacitor charged from said source, a first diac operatively connecting said first capacitor to the control electrode of said rectifier, said first gating circuit gating said rectifier into conduction when the voltage across said first capacitor exceeds a threshold level, and a discharge circuit connected to inhibit charging of said capacitor when said switch means is in said second state, so that said first gating circuit can gate said rectifier into conduction only when said switch means is in said first state, and a second gating circuit including a second capacitor, a second diac operatively connecting said second capacitor to the control electrode of said rectifier, and potentiometer means connected to said ac source to provide an adjustable voltage for charging said second capacitor, said second gating circuit gating said rectifier into conduction when the voltage across said second capacitor exceeds said threshold value and when said switch means is in said second state in which said first capacitor is discharged.

2. A control circuit according to claim 1 wherein said discharge circuit comprises:

a pair of series connected, complementary transistors one of which is biased on onlY when said switch means is in said second state and the other of which has a grounded base, a pair of unidirectionally conducting means respectively connecting said first diac other terminal to the otherwise unconnected collector and emitter elements of said complementary transistors and respectively oriented to permit discharge of said first capacitor through said other complementary transistor for positive or negative charge on said first capacitor.

3. A control circuit according to claim 1 wherein said switch means comprises:

first and second transistors connected so that one conducts when the other is off, and a separate interval timing circuit associated with each transistor and operative to turn on that associated transistor after the other transistor has been on for a selectable interval of time.

4. A control circuit according to claim 3 wherein the interval timing circuit associated with each transistor comprises:

a capacitor having one terminal connected to a non-control element of the other transistor, means supplying a selectable voltage via a resistor to the other terminal of said capacitor, the values of said capacitor, said resistor, and said selectable voltage establishing said interval of time, unidirectionally conducting means connecting said capacitor other terminal to the control electrode of the associated transistor, and a resistor connected between said associated transistor control electrode and said other transistor non-control element.

5. A device according to claim 1 wherein said load comprises an incandescent or a fluorescent lamp.

6. A control circuit according to claim 1 and adapted to supply power to two lamps, further comprising:

another controlled rectifier connecting said ac source to the second lamp, a third gating circuit for gating said other rectifier into conduction when the voltage across a third capacitor charged from said source exceeds a threshold level and when said switch means is in said second state, and a fourth gating circuit for gating said other rectifier into conduction when the voltage across a fourth capacitor charged from an adjustable voltage source exceeds a threshold level while said switch means is in said first state.

7. A lamp control circuit comprising:

a source of ac power connected to said load via a controlled rectifier, a first gating means for initiating conduction of said rectifier when a signal derived from said source exceeds a certain value, said first gating means including a first capacitor charged from the ac source to provide said derived signal, and a first diac operatively connected between said first capacitor and the control electrode of said rectifier, a second gating means comprising a potentiometer connected to said source to provide an adjustable voltage, a second capacitor charged by said adjustable voltage, and a second diac operatively connected between said second capacitor and said rectifier control electrode, said second gating means initiating conduction of said rectifier at a phase angle of the ac cycle established by the magnitude of said adjustable voltage, switch means continuously alternating between two stable states and having separate interval timing means to establish the respective dwell time in each of said stable states, and disable circuit means, comprising a circuit discharging said first capacitor when said switch means is in one of said stable states, for preventing said first gating means from initiating conduction of said rectifier when said switch means is in said one stable state.

8. A control circuit according to claim 7 wherein said controlled rectifier comprises a triac connected in series with one line between said ac source and said load.

9. A control circuit according to claim 8 wherein said switch means comprises first and second transistors operatively connected so that one transistor conducts when the other is off, each interval timing means comprising:

a capacitor charged through a resistor by a voltage of controllable magnitude, said capacitor being connected between the non-control electrode of one transistor and a diode leading to the control electrode of the other transistor, another resistor shunting said diode and said capacitor.

10. A control circuit according to claim 7 wherein said switch means is powered by substantially unfiltered dc voltage supplied during half of each ac source cycle by a single diode.