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Alarm unit for limit switches or flow switches

Have you ever faced the frustration of dealing with an overflowing tank or a pump running dry? These unexpected events can result in costly damage and inconvenience. A reliable floater switch alarm system can provide early warnings, allowing you to take prompt action and prevent further issues. This project guides you through building a do-it-yourself floater switch alarm system using a PIC12F508 microcontroller.

The circuit for this project is relatively simple and requires very few components. The system is designed to operate with a 12V DC power supply and utilizes a 230V AC buzzer unit for audible alerts.

Prototype version of the alarm controller.

The circuit includes a mute function that allows you to temporarily silence the alarm for a specified duration. Additionally, a built-in timeout mechanism ensures continuous alarm activation if the floater switch remains closed for an extended period, indicating a potential emergency. This project is suitable for various applications, including home or industrial monitoring, and environmental monitoring.

The firmware for the microcontroller will control the operation of the alarm system. It should perform the following tasks:

  • Monitor the floater switch: Continuously read the input pin from the floater switch.
  • Activate the alarm: If the floater switch detects a change in water level (e.g., rising water), activate the buzzer or alarm.
  • Mute function: Allow the user to temporarily mute the alarm by pressing a button.
  • Timeouts: If the alarm remains active for an extended period, it may indicate a serious issue.

The firmware for this project is developed using the MPLAB X IDE and the XC8 C compiler. The latest firmware source code is available in the firmware directory of the project repository. The compiled firmware is also available in the release section of the project repository.

To protect the electronic components from moisture and other environmental factors, it is recommended to enclose the system in a waterproof enclosure. In our prototype build, we use an 100mm × 68mm × 50mm project enclosure to mount this controller.

This is an open hardware project. All the project firmware source code, design files, and compiled binaries are available on the GitHub project page.

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