0x09: 4 ch Taguchi gas sensor array DIN50

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Background

Please see the e-nose project page for an elaborate description as well as practical examples.

Function

This PCB breaks out the connections to four Taguchi type gas sensors and effectively forms an array of sensors; the sensor part of an electronic nose. The board will accomodate both the more expensive 6-pin Figaro Engineering-type gas sensors as well as the cheaper 6-pin products from e.g. HW Sensor.

The optional onboard four channel 8 bit analogue-to-digital converter has built-in OneWire communication, which allows the response of the four Taguchi gas sensors to be read remotely over a very long wire. An additonal digital temperature transmitter (DS18B20) and a combined temperature and humidity transmitter (DHT11) allows for monitoring of two addtional environmental parameters over the OneWire bus. The current consumption is roughly 160 mA per Taguchi gas sensor, so the entire board consumes around 650 mA @ 5 VDC or 3.3 W depending on the type of gas sensor. The DS2401 identifies the printed circuit board if other OneWire components with unique MAC addresses are not mounted. Sensitivity/baseline of each Taguchi gas sensor can be manipulated by adjusting the respective trimpotentiometers.

 

License terms
The 0x09 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

Circular, 50 mm (diameter). Double-sided.

Rendering and photos

DipTrace 3D rendering with components, frontside (Rev. 1)

DipTrace 3D rendering with components, backside (Rev. 1)

Photo of the PCB frontside, components mounted (Rev. 1)

Photo of the fully assembled PCB (Rev. 1)

Bill of materials

4 pcs. Taguchi gas sensor

4 pcs. trimpotentiometer, 50k, form factor 3296W

2 pcs. 2×4 pin header

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

1 pcs. LED, 1206

 

optional (OneWire)

1 pcs. DS2401 silicon serial number, SOT-23-5

1 pcs. DS2450 four channel 8 bit analogue-to-digital converter, SOIC-08

1 pcs. capacitor, 100 nF, form factor 1206

1 pcs. resistor 4k7, 1206 (pull-up for DQ)

1 pcs. DS18B20, digital temperature transmitter, TO-92

1 pcs. DHT11 (or DHT22) combined digital temperature and humidity transmitter, 4 pin SIL package (0.1 “/2.54 mm)

 

Estimated cost

Four Taguchi gas sensors, two 2×4 connectors, and four trimpotentiometers should not cost more than EUR 20,- depending on the type of sensors (note: Figaro Engineering sensors cost a lot more than the cheaper MQ-series sensors). The analogue-to-digital converter can also be pricy, but it gives immense flexibilty, when monitoring remote locations. The OneWire protocol supports quite long data buses exceeding 100 m.

Downloads

DipTrace v. 3.0.0.0 PCB design file: 0x09_DipTrace_PCB

Gerber files: 0x09_Gerber

Sensor datasheet, HW Sensor: MQ-2

Sensor datasheet, HW Sensor: MQ-3

Sensor datasheet, HW Sensor: MQ-4

Sensor datasheet, HW Sensor: MQ-5

Sensor datasheet, HW Sensor: MQ-6

Sensor datasheet, HW Sensor: MQ-7

Sensor datasheet, HW Sensor: MQ-8

Sensor datasheet, HW Sensor: MQ-9

Sensor datasheet, HW Sensor: MQ131

Sensor datasheet, HW Sensor: MQ135

Sensor datasheet, HW Sensor: MQ136

Sensor datasheet, HW Sensor: MQ137

Sensor datasheet, HW Sensor: MQ138

Links

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