Evolution of a Blog

This blog has evolved as I have as a maker. It starts at the beginning of my journey where I began to re-tread my tires in the useful lore of micro electronics and the open-source software that can drive them. While building solutions around micro-electronics are still an occasional topic my more recent focus has been on the 3D Printing side of making.

Tuesday, July 15, 2014

Heat and Gas Monitor / Switch

This device was originally designed to monitor a 3D printer for temperature or gas (e.g. smoke) above a certain threshold at which point the printer would be powered down.   The circuit consists of an Arduino Nano connected to a temperature sensor and a gas sensor.   Two LEDs and a buzzer provide feedback.  The circuit drives a relay that can close the PS_ON circuit of an ATX type power supply (or a relay that is part of the power supply circuit for the printer).

There are two different boards with one being 50x50mm that would have the relay mounted off the board as shown in the picture to the right.   The two sensors are also mounted off the board as is the buzzer (upper right of photo).

The other board configuration is 50x100mm and has room for the relay on the PCB.  The relay could be part of a power supply circuit (DC or even AC) but the PCB is really designed to be part of an PS_ON circuit of an ATX power supply as it has an bypass switch that can be used to close that circuit.

Both of the boards are available in a kit form as there are a wide variety of ways that they could be mounted and as many ways to connect the board to sensors.

The PCB also has a connection point for the serial port of the Arduino for diagnostic information output by the sketch that drives the monitor.

As stated above, the monitor was designed for a 3D Printer but it could be used to monitor just about anything for heat and gas where a relay needs to be triggered.  I used the MQ-2 sensor looking for smoke but other MQ sensors could be used for other gas types.

Below is a documentation index for the Heat and Gas Monitor / Switch PCB:

Part 1 - Introduction
Part 2 - Hardware Configuration Options
Part 3 - Operation
Part 4 - Software Configuration
Part 5 - Assembly


  1. Whether you're a professional that works with gas regularly or just someone looking for a better way to monitor potential gas leaks in their home or business, having a gas monitors can make all the difference. There are so many different products out there to choose from. Many people will see the array of commercial products and assume that they're not going to find anything that they need for a smaller scale or budget.

  2. The above comment is obviously spam but makes a good point. My project puts you in control for the building of a custom gas and/or heat monitor. I am not intending to supplant commercial offerings such as those above! You build and use my kit to your own specifications (and risk)!