Title: LED Filament Analysis 
By: Don Kuenz

Abstract: 
  An AC chip-on-board LED (CoB) LED filament contains many LED
  chips mounted on a thermally efficient substrate beneath a
  uniform phosphor coating. This webpage examines one such
  highly efficient filament.

Keywords: analysis, cob, led, filament

LED Filament Analysis

Contents

Data

full voltage

Figure 1. Filament at full voltage.

low voltage

Figure 2. Autotransformer adjusted AC voltage to
illuminate each elemental CoB.

Radiograph top

Figure 3. Radiograph top.

Radiograph side

Figure 4. Radiograph side.

68 VDC

Figure 5. 68 VDC applied via Red wire.

68 VDC reversed

Figure 6. 68 VDC reversal applied via Red.

Preliminary Findings

Save the side radiograph image to disk. Then open the image with a local graphical App and Zoom In until six humps become visible. In my opinion these humps show wire connections to seven CoBs.

Notes


© 2026 Don Kuenz