Here is the circuit of a little label sensor ideal for detecting labels on bottles. The circuit offers a peak sensing distance of 2.5 mm (operating range 0.2 mm to 15 mm) backed up by the proven ...
Recently an ad on YouTube about an acoustic light sensor/switch module piqued my interest. Out of curiosity, I contacted the online vendor and bought a pair. Named MR-SK50A, the module is less popular ...