As you can see from this blog entry I developed the basics for this project two years ago as an alarm / shutoff switch for the RepRap 3D Printer kit that I had just assembled...and that had smoked!
Since then I have had circuit boards that I have done nothing with until now! This instructable will tell you how to take one of my PCBs (available here on eBay) and turn it into an Arduino Based Smoke / Heat Alarm.
As I stated above, 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 above. 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.
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. 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.
The PCB's upon which this project is based are sold AS-IS with the assumption that the buyer will properly assemble the device, configure and load the appropriate software sketch, and will then assume responsibility for its operation. If you are not comfortable with the "as-is" nature of the PCB they can return the product (at your cost for shipping) for a full refund. The seller will NOT be responsible for prints terminated by the monitor triggering as the result of bad parameter input or any other malfunction of the monitor. Likewise the seller will NOT be responsible for the monitor missing a shutdown circumstance that results in damage whether due to bad parameter input or any other malfunction of the monitor. In no event shall the seller be liable for any direct, indirect, putative, incidental, special consequential damages, to property or life, whatsoever arising out of or connected with the use or misuse of this product. In no event shall the seller be liable for any direct, indirect, punitive, incidental, special consequential damages, to property or life, whatsoever arising out of or connected with the use or misuse of our products. - See more at: http://injury.findlaw.com/product-liability/are-p...
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Step 1: Source Your Components
From the Arduino, bottom left, and moving around counter clockwise, here are the elements of the circuit that will need to be sourced:
- Arduino Nano
- Headers (to be broken into appropriate sizes)
- Pull-up Resistors (10k Ohm)
- DHT-11 Temperature Sensor
- MQ-02 Smoke / Gas Sensor
- Two Screw Terminals (two and three connector)
- Red and Green LEDs
- Bypass Switch (SPDT)
Step 2: Breakup Header Into Appropriate Sizes
Break the large headers into the appropriate sizes. All components could be soldered to the board...or none...so cut the number you need!
Step 3: Solder Components And/or Headers to Circuit Board
Do your soldering! When done stick on the components that were not soldered.