A PCBA count sensor is built around the WF8002 metering chip: the sensing coils are integrated into the PCB itself, and the board counts the rotation of a metal plate positioned a few millimetres below it. It is used in water and gas meter production where a compact, non-magnetic counting front end has to fit inside the meter housing.
The standard output is a pulse signal covering both forward and reverse running. TTL and open-collector (OC) versions are available, and other output modes can be customised for a specific host MCU or communication module.
The sensor is externally powered at a rated 3.0–3.6 V. Working current is below 6 µA for residential meters and below 20 µA for commercial meters. The higher the supply voltage, the longer the detection distance.
The longest stable working distance depends on the metal rotor. A 304 stainless rotor of 16 mm diameter and 0.2 mm thickness is the normal size, and a larger rotor diameter allows a longer detection distance. The rotor and the PCB sensor plane must be concentric, parallel and mounted on a stable holder.
| Output | TTL / OC pulse, forward and reverse running |
| Supply voltage | 3.0–3.6 V DC |
| Working current | <6 µA residential, <20 µA commercial |
| Target | 304 stainless rotor, 16 mm × 0.2 mm typical |
| Design highlights | Anti-magnetic, ultra-low power, compact, customisable |
