Background: In the manufacture of domestic incandescent lamps, one of the lamp lead wires is welded to the lamp base. This produces the small metal bead that can be seen where the edge of the screw-in base meets the glass bulb. A lamp manufacturer built a new finishing machine which was capable of producing five lamps per second, but the conventional welder could only make one weld per second.

Project: Product Resources designed and built a welder power supply that can complete a weld cycle in less than 200 milliseconds. The essential component is a constant current regulator capable of charging an energy storage capacitor to a predetermined voltage in 120 milliseconds. When the weld electrode makes contact, the capacitor energy fuses the lamp wire end, and the power supply maintains an arc for enough time to complete the weld, extinguishes the arc, and recharges the capacitor for the next weld. An optically-isolated pulse signals the machine control computer that the weld is complete. The Product Resources welders are in daily service on the incandescent lamp production line.

Technologies: power MOSFET switching series regulator, kilowatt linear power supply, digital logic, opto-isolated computer interface

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