HardLabs

Air quality monitor

ajkumar-1907·power-converter-lib·air-quality-monitor/air-quality-monitor.kicad_pcb

Air quality monitor PCB layout, top view — open source ESP8266 board by ajkumar-1907

About the Air quality monitor PCB

Air quality monitor is an open source ESP8266 PCB design by ajkumar-1907, published on GitHub under the MIT license. It is a 2-layer board measuring 68 × 47.4 mm, with 52 components from 31 distinct parts.

Its main chip is the ESP-12E, from the ESP8266 family. Other key parts include the MQ-135, MT3608, TP4056-42-ESOP8, AMS1117-3.3 and CH340C. By type, the board carries 16 resistors, 13 capacitors, 8 diodes, 6 ICs, 4 connectors and 2 transistors.

It belongs with the sensors, iot & wireless and power & battery designs in this gallery.

From the project

Open-source library of power electronics converter topologies — KiCad schematics, working principles, use cases, and design notes for DC-DC, AC-DC, DC-AC, and AC-AC converters. Free to use, modify, and build on.

A battery-powered, Wi-Fi connected air-quality monitor built around an ESP-12E (ESP8266) and an MQ-135 gas sensor. It reads gas concentration, shows it on an SSD1306 OLED, and can send the data over Wi-Fi. The board has its own USB-C programming interface, a Li-ion charger and power regulation.

The board combines six functional blocks on one 2-layer PCB:

1. Power path: USB-C supplies 5 V. The CC pins have 5.1 kΩ pull-downs (R6, R7), so a USB-C host provides power, and TVS diodes (D6, D7, D9) protect the USB lines. The TP4056 charges the Li-ion cell on J1 at about 1 A (set by R13 = 1.2 kΩ).…

Air quality monitor, from the project README
From the project README

Main components on the Air quality monitor

ESP-12EMQ-135MT3608TP4056-42-ESOP8AMS1117-3.3CH340C

Air quality monitor bill of materials (BOM)

52 components, 31 distinct parts.

QtyPartRefs
1
ESP-12E
U1
1
MQ-135
U2
1
MT3608
U4
1
TP4056-42-ESOP8
U5
1
AMS1117-3.3
U6
1
CH340C
U7
2
SS8050
Q3, Q4
1
Conn_01x02_Pin
J1
1
Conn_01x04_Pin
J2
1
Conn_01x03_Pin
J3
1
USB_C_Receptacle_USB2.0_16P
J23
2
SW_Push
SW1, SW2
1
GREEN
D1
2
RED
D2, D3
3
LESD5D5.0CT1G
D6, D7, D9
2
SS34
D8, D10
1
L
L1
2
22uF
C1, C2
4
10uF
C3, C4, C6, C7
5
0.1uf
C5, C22, C23, C24, C25
Show 11 more
QtyPartRefs
1
10uF/25V
C27
1
10nf
C28
2
R
R1, R2
3
1K
R3, R12, R16
3
10k
R4, R5, R15
2
5.1K
R6, R7
1
4.7K
R8
2
10k
R9, R10
1
0E
R11
1
1K2
R13
1
220E
R14

Air quality monitor design files

The KiCad project lives in the ajkumar-1907/power-converter-lib repository on GitHub; these links point at the commit this page was built from.

Air quality monitor: common questions

What microcontroller does the Air quality monitor use?

The Air quality monitor is built around the ESP-12E, from the ESP8266 family.

How big is the Air quality monitor PCB?

The Air quality monitor measures 68 × 47.4 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Air quality monitor?

52 components, from 31 distinct parts. The full bill of materials is listed on this page.

Where can I download the Air quality monitor design files?

From the ajkumar-1907/power-converter-lib repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the Air quality monitor design in my own project?

Yes, under the terms of its MIT license, which ajkumar-1907 chose for the repository.

Can I test firmware for the Air quality monitor without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug ESP8266 firmware against it before you order a PCB.

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