This ESP32 project adds a remotely triggered 12 V siren to a home-automation system. An ESP32 Wemos development board listens for MQTT messages and uses an IRLB8721 N-channel MOSFET to switch the siren. It is a prototype for commanded sound output—not a certified fire alarm, monitored security system, or substitute for required life-safety equipment.
What the project does
Dave Wilson’s Hackster.io build, published December 28, 2019, connects a 12 V siren to a home-automation setup through an ESP32 Wemos development board and MQTT. The controller subscribes to three topics:
| MQTT topic | Described behavior |
|---|---|
diy/system/panic |
Requests a loud oscillating siren. |
diy/system/fire |
Requests a loud continuous siren. |
diy/system/who |
Intended as a device status update; the author describes this feature as still under construction. |
The author’s wider system uses Mosquitto as its MQTT server and includes Raspberry Pi servers and Espressif boards. The siren is an output device controlled by messages; the project description does not establish that it detects smoke, intrusion, or other hazards on its own. See Dave Wilson’s Hackster.io build.
How the hardware is arranged
The ESP32 does not power the siren directly. A switching component provides a path for the 12 V load: Wilson’s design uses an IRLB8721 N-channel MOSFET, while a separate ESP32 siren tutorial demonstrates relay control. These are examples, not a controlled comparison or a guarantee that either component suits every siren. Check the selected sounder’s voltage and current requirements and the switch’s load and control ratings before choosing parts. ESP32IO’s siren tutorial shows a relay example using GPIO 16.
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Wilson prototyped the circuit on a breadboard, then soldered it to an Adafruit half-size Perma-Proto board. The project describes programming and debugging the ESP32 Wemos on the protoboard and placing the assembly in an electrical box. Its page also notes an exposed siren power wire and suggests routing the wire through the enclosure with insulation or sealant. That account is not a verified weatherproofing specification or a complete electrical installation method.
Parts and tools listed by the build
The Hackster parts list names these components:
- One Wemos ESP32 development board
- One IRLB8721 N-channel MOSFET
- One 7805 linear regulator
- One Adafruit half-size Perma-Proto board
- Two 100 μF capacitors, two 22 μF capacitors, and three 0.1 μF capacitors
- One 2.1 mm DC barrel jack and headers
- One 12 V, 2 A power supply
- One 12 V, 15 W, one-tone outdoor siren
- One 10 kΩ resistor and an electrical box enclosure
The listed tools include a soldering iron, solder, screwdriver or multitool, drill or driver, screws, and drill bits. These are the author’s project inventory, not independently tested recommendations. Retail board names can be ambiguous: confirm a replacement is actually ESP32-based rather than an ESP8266 variant, and verify every substituted part’s ratings.
Rank #2
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- Over-the-Air Update Support: Configure OTA functionality through a compatible ESP-32 software framework to update deployed firmware over Wi-Fi without reconnecting the board by USB for every revision
How to choose compatible parts
Use “12V DC alarm siren” as a starting description when looking for the project’s central output, then verify the actual sounder’s specifications. The project lists a 12 V, 15 W siren and a 12 V, 2 A supply; those are component-list entries, not measured performance results or proof that the supply is suitable for another siren or the complete circuit.
- Sounder: Match its rated voltage and current to the intended supply and switching circuit. Confirm that it provides the required sound pattern; the source’s siren is listed as one-tone.
- Switch: Check both the load rating and the control requirements of the MOSFET or relay you select. The sources do not report comparative efficiency, reliability, sound output, or installation safety for the two approaches.
- Power and wiring: Confirm that the supply, wiring, connectors, and enclosure suit the actual load and intended location. The cited build does not establish installation rules for a particular jurisdiction.
- Board: Check the specific Wemos board revision and module markings rather than assuming every similarly named listing uses the same ESP32 module. Espressif’s ESP32-WROOM-32D/32U datasheet describes those modules and marks that series as not recommended for new designs; it does not verify which module is fitted to the project’s Wemos board. Read the ESP32-WROOM-32D/32U datasheet.
What this prototype does not establish
The Hackster build is described as a first-phase prototype. The author’s characterization of the code as “production ready” is not evidence of product certification or field validation. Neither the build nor the independent tutorial establishes fire or security certification, backup operation, compliance with installation rules, or suitability as a life-safety device. Treat it as a home-automation siren output and retain approved, appropriately installed alarm equipment wherever it is required.
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Best Value
- 2.4GHz Dual Mode WiFi + Bluetooth Development Board
- Ultra-Low power consumption, works perfectly with the Arduino IDE
- Support LWIP protocol, Freertos
- SupportThree Modes: AP, STA, and AP+STA
- ESP32 is a safe, reliable, and scalable to a variety of applications
Rank #4
- 2.4GHz Dual Mode WiFi + Bluetooth Development Board
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