If you have a pool and want to go for a swim, you may want to know the temperature before, literally, taking the plunge. The sensor setup seen here is able to detect pool temperatures and monitor its battery level over WiFi, but there’s one small catch. The floating sensor is, in fact, in the form of a quite realistic crocodile head.
To make this unit, the head is partially bored out with a razor knife, creating a nice rectangular cavity for the electronics to reside. Data transmission and overall control is taken care of using an ESP8266 Wemos D1 mini Pro board. An external antenna facilitates proper data transmission, and a small solar panel is implemented to keep its LiPo battery topped off. Temperature readings are taken care of by a waterproof sensor that sticks out the bottom of the head.
Once the circuitry is stuffed into the beast’s head, it’s then sealed up with industrial foam. With this sensor in place, temperature can be transmitted to a smartphone viathe Blynk app, or you can use a MQTT broker for whatever other pool temp reading uses you have in mind. Code for the croc’ sensor is available on GitHub.