A door chime assembly with a transformer assembly mounted within an electrical box and proximately to a chime. The clip-on handle can be used to securely hold all types of containers either with or without a lip at its opening. The decoupler assembly further includes a hub, that is configured to be coupled to a driven shaft, and a torsion spring that transmits rotary power between the carrier and the hub. Another embodiment is a system including a unique soot loading metric.