The SparkFun H2OhNo! is a water sensor alarm kit that you build yourself. When water is detected across the sense pins an alarm goes off and an LED starts blinking. If you’ve ever had a water heater explode or tried to create submersible electronics you know how important it is to be able to detect when water is around!

Underneath the default function of H2OhNo! is a small but powerful development board for the ATtiny85 microcontroller. The board includes a buzzer, LED, a coin cell battery, and the ability to detect analog and digital sensors. This mixture of parts creates a great low-cost tool to learn how to program and sense things!

This board can be re-programmed to be an Annoy-A-Tron (originally made by Think Geek). Please annoy respectfully, otherwise your board may get demolished.

Note: Please check the hookup guide below for helpful tips and assembly instructions.

Note: Due to the requirements of shipping the battery in this kit, orders may take longer to process and therefore do not qualify for same-day shipping. Additionally, these batteries can not be shipped via Ground or Economy methods to Alaska or Hawaii. Sorry for any inconvenience this may cause.

Get Started with the H2OhNo! Guide

Includes

1x H2OhNo! PCB

1x ATtiny85 (Pre-Programmed)

1x 20mm Coin Cell Battery Holder

1x CR2032 Coin Cell Battery

1x Slide Switch

1x 2kHz Piezo Speaker

1x 8-pin DIP Socket

1x Super Bright Red LED

2x Jumper Wire

1x Capacitor 0.1uF

Features

22.86mm x 52.07mm (0.90" x 2.05")