Smoke detector with gas sensor TGS 813 – source The simple schematic diagram of a smoke detector presented here utilizes the gas sensor TGS 813 as the main detecting component. The circuit is pretty ...

At the heart of this ultra simple smoke alarm is H21A1, which is a photo-interrupter module consists of a gallium-arsenide infrared LED coupled to a silicon phototransistor in a plastic housing. The ...