SDG #109 AC LED Dimmer Testing with PCBs from JLCPCB - Lighting Controller Project Part 8

Part 8 of the lighting controller build moves from schematic and layout work onto real hardware, with the freshly manufactured dimmer PCBs populated and powered up on the bench. The focus here is the mains side of the design: phase angle control of AC LED lamps, reliable zero crossing detection, and whether the switching stage behaves predictably across the full dimming range rather than just at comfortable mid brightness.

Measurement is the interesting part. Probing a mains referenced dimmer safely means using a differential probe rather than a grounded scope lead, and the captured waveforms show exactly where the conduction angle starts and how cleanly the switch turns on each half cycle. That matters because a lot of dimmer problems only show up at the extremes: buzzing, uneven brightness steps, visible flicker at low levels, or a lamp that simply drops out below a certain threshold. Watching the waveform alongside the lamp behaviour makes it clear whether a fault sits in the control firmware, the detection circuit, or the lamp’s own driver.

The practical takeaway for anyone attempting a similar project is that retrofit LED lamps vary enormously in how they respond to leading edge dimming. Some track smoothly, others behave badly regardless of how well the controller is designed, so testing with several lamp types is essential before blaming your own board. There is also useful insight into how well a low cost prototype PCB order holds up for a mains circuit, including clearance, trace width, and general build quality of the delivered boards.