Capacitor charging circuit for timing light power source

• US 4,965,494 A
• Filed: 10/21/1985
• Issued: 10/23/1990
• Est. Priority Date: 10/21/1985
• Status: Expired due to Term

• Current Assignee: Snap-On Incorporated
• Original Assignee: Snap-On Tools Company LLC (Snap-On Incorporated)
• Inventors: Lindhard, Gordon, Wisneski, Leonard J. Jr.
• Primary Examiner(s): LaRoche, Eugene R.
• Application Number:
  US06/789,474
• Time in Patent Office: 1,828 Days
• Field of Search: 315/241 R, 315/241 S, 315/241 P, 307/584, 331/173, 331/149, 331/153
• US Class Current: 315/241.00S
• CPC Class Codes: H05B 41/34 to provide a sequence of flashes

Abstract

A strobe light power source includes a capacitor which is alternately charged through an inverter transformer and a rectifier and discharged through a strobe lamp. A MOSFET switch is connected in series with the transformer primary and has applied to its gate electrode a rectangular wave output signal from an oscillator. The oscillator and the transformer primary are coupled to a power supply independently of each other. A breakdown diode is connected in parallel with the MOSFET to limit the voltage thereacross.

Claims

1. In a strobe light having capacitance means successively charged by a power supply through a charging circuit and discharged through a strobe lamp, the improvement comprising:

active electronic switch means including a metal oxide semiconductor field effect transistor coupled to the charging circuit for controlling the input current thereto during charging of the capacitance means, oscillator means coupled to the power supply independently of the charging circuit and generating a rectangular wave output signal of a predetermined frequency, and means for coupling said rectangular wave output signal to said electronic switch means for controlling the operation thereof.

2. The strobe light of claim 1, wherein said predetermined frequency is 20 KHz.

3. The strobe light of claim 1, wherein said rectangular wave output signal has a duty cycle of essentially 50%.

4. The strobe light of claim 1, wherein said means for coupling includes a resistor.

5. The strobe light of claim 1, and further comprising voltage control means connected in parallel with said electronic switch switch means for limiting the voltage thereacross.

6. The strobe light of claim 1, wherein the power supply includes low pass filter means.

7. In a strobe light having capacitance means successively charged by a power supply through a charging circuit and discharged through a strobe lamp, the improvement comprising:

active electronic switch means including a metal oxide semiconductor field effect transistor coupled to the charging circuit for controlling the input current thereto during charging of the capacitance means, oscillator means coupled to said electronic switch means for controlling the operation thereof, and voltage control means connected in parallel with said electronic switch means for limiting the voltage thereacross.

8. The strobe light of claim 7, wherein said oscillator means is coupled to the power supply independently of the charging circuit.

9. The strobe light of claim 7, wherein said voltage control means includes a breakdown diode.

10. A charging circuit for a strobe light having capacitance means successively charged by a power supply and discharged through a strobe lamp, said charging circuit comprising:

transformer means having a primary winding coupled to the power supply and a secondary winding coupled to the strobe lamp, active electronic switch means including a metal oxide semiconductor field effect transistor connected in series with said primary winding for controlling the current therethrough during charging of the capacitance means, oscillator means coupled to the power supply independently of said transformer means and generating a rectangular wave output signal of a predetermined frequency, means for coupling said rectangular wave output signal to said electronic switch means for controlling the operation thereof, and voltage control means connected in parallel with said electronic switch means for limiting the voltage thereacross.

11. The charging circuit of claim 10, wherein said means for coupling includes a resistor.

12. The charging circuit of claim 10, wherein said predetermined frequency is 20 KHz.

13. The charging circuit of claim 10, wherein the power supply includes low pass filter means.

14. The charging circuit of claim 10, wherein said voltage control means includes a breakdown diode.

15. The charging circuit of claim 10, wherein said rectangular wave output signal has a duty cycle of essentially 50%.