0x13: NodeMCU breakout board with relay

Background

Internet of Things (IoT) has moved one step further into every home of a maker with the launch of the NodeMCU based on the popular ESP8266 from Espressif Systems. However, connecting to sensors for measuring and actuators for controlling something in the real World requires a few extra components besides the NodeMCU itself. This design forms the missing bridge between the two.

Function

This design integrates a simple linear power supply based on a robust Grätz bridge, a capacitor, and a linear regulator capable of delivering 800 mA continuous power. Simply plug in any available power supply in the jack, upload sketch to the NodeMCU, connect the analogue/digital sensor you have, connect to a WLAN network, and you are online with your measurement.

A power relay is included for control of mains voltages (10 A, 230 VAC). Headers for connecting to the analogue input, a general purpose input/output as well as a dedicated digital pin for OneWire temperature transmitters are also included.

All pins on the NodeMCU are broken out to headers as well.

The relay is controlled via pin D7. OneWire sensors are interfaced via pin D8. The GPIO is wired to D0.

License terms

The 0x13 design is published under the Creative Commons Unported 3.0 License.  I do not profit from this design, neither should you. You are welcome to adapt, modify, and redistribute this design as long as the license terms are respected.

Physical size of PCB

50 mm (length) by 50 mm (width). Double-sided.

Rendering and photos

 

DipTrace 3D rendering, frontside with components

DipTrace 3D rendering, frontside without components

DipTrace 3D rendering, backside with components

DipTrace 3D rendering, backside without components

 

 

Bill of materials

5 pcs. LL4007 general purpose power diode, 1 A, 1 kV, D-214

1 pcs. 220 uF, 16 V, electrolytic capacitor, 8.25 mm

4 pcs. 100 nF ceramic capacitor, 1206

1 pcs. linear regulator, AMS1117-5.0, 5 VDC, 800 mA

1 pcs. LED, 1206

1 pcs. resistor, 715R (current-limiter for LED)

1 pcs. NPN BC517 transistor, SOT-23

1 pcs. resistor, 100R (base-current limiter for transistor)

2 pcs. resistor, 1206 (voltage divider for analogue-to-digital converter)

1 pcs. resistor, 4k7 (pull-up for OneWire data pin)

2 pcs. 1×15 male header, 2.54 mm (0.1″)

2 pcs. 1×15 female header, 2.54 mm (0.1″)

1 pcs. power barrel jack, 2.1 mm pin, 5.5 mm barrel

1 pcs. relay, 5 VDC coil, 230 VAC/10 A

Estimated cost

Diodes, resistors, relay, capacitors, headers, transistor, and regulator should not cost more than EUR 3,-.

Downloads

DipTrace v. 3.1 PCB design file: 0x13 nodeMCU breakout 50×50 – ratlined-public

Gerber files: 0x13

Links

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