The “ESP32 IoT Relay Board” is a credit card-sized ESP32 board with four small 250VAC/30VDC 7A relays that runs Tasmota open-source firmware and supports Alexa & Google Assistant for voice control.
There are so many ESP32-based relay boards on the market that I don’t usually feel the need to cover new ones, but Igor Mileshin’s ESP32 IoT Relay Board is smaller than most so I thought it might be interesting to some. The smallest quad-channel relay board I’ve seen so far is the one by Seeed Studio using an STM32 MCU and solid-state relays that measures just 60 x 40mm, but the relays only support up to 2A.
ESP32 IoT Relay Board specifications:
- Wireless module – ESP32-WROOM-32D
- SoC – Espressif ESP32-D0WD dual-core Tensilica LX6 processor @ 240 MHz
- Storage – 32Mbit SPI flash
- Connectivity – Wi-Fi 802.11 b/g/n up to 150 Mbps, Bluetooth 4.2/5.x LE
- Relays
- 4x “industrial-grade” relays supporting 7A / 250VAC; 7A / 30VDC (Exact part name not provided, but it looks like Hongfa HF46F-G)
- Connection via screw terminals
- USB – 1x USB-C port for programming and debugging
- Expansion
- Two headers for 12x GPIO
- 1x I2C header
- Misc
- Power LED
- 4x relay status LEDs
- BOOT button
- Power Supply – 5V DC via USB Type-C port
- Dimensions – 80 x 50mm
Users can program the board with Arduino, ESP-IDF, or MicroPython, or simply run Tasmota open-source firmware since it’s compatible with the board and that’s how Alexa and Google Assistant support is integrated. There’s also a GitHub repo, but I’ve been told it’s under development, and right now there are only Arduino and MiroPhython samples to turn on and off the LEDs in a loop…
I don’t see any safety certifications mentioned for the board, and we’re just told that the board features “an open PCB track with enhanced solder masking, it maximizes current flow, ensuring reliable performance under high-load conditions”. You can see the board in action in the video below.
The credit card-size ESP32 IoT Relay Board is now listed on Kickstarter with a $2,000 funding target that’s already been surpassed. Rewards start at $29 for the “Early Bird Special” perk limited to 50 pieces, and the MSRP after the crowdfunding campaign is over should be $45. Shipping adds $20 to the US and $25 to the rest of the world, and backers should expect the rewards to ship by May 2025 if everything goes according to plans.
Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.
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“I don’t see any safety certifications”
That’s because it isn’t safe
The layout is abysmal. Though there are slots between the channels, the track clearance between near the relay pins is ~0.5mm, for uncovered tracks (the clearance between component pads is 3mm, for a reason). DO NOT USE THIS WITH 115V/230V!
The low voltage side is equally bad, the bottom side ground pours have large, unconnected islands (i.e. are good antennas). The tracks take pointless detours, and so on …
And finally, when do people learn to do a proper antenna cutout, Espressif recommends IIRC 15mm to both sides with no copper (preferably, no PCB).