April 2022

Steve talked about a 'Fume Cupboard Sash Alarm' for laboratories.

Users leave the window sash up when they're finished, so the fans run at high speed.

This causes extra load on the building air conditioning systems, wasting energy, money & CO2 emissions. The waste adds up quickly when you have 100's of fume cupboards.

The Sash Alarm is a simple alarm box with magnetic reed switch that beeps if the sash is left open longer than 10 mins. It keeps beeping periodically until the Sash is closed.

Processor is an Arduino Nano - cheap, simple programming, OLED library available for free download. It is a huge time saver to use parts that have a code library already available. I often choose the device (sensor, display etc) based on whether there's a library or not.

Reed switch - at $8 is expensive but a small, self adhesive slim line switch is desirable.

2kHz beeper uses PWM output for Arduino.

The software needs to operate the beeping and beep timing while simultaneously scan the switch to see if the sash has moved. So a simple delay() function won't work. The utility function millis() was used to allow the loop to continue switch scanning.

Early feed back on the prototype is that they want a better quality enclosure and custom front panel label. More cost, but the product will be more professional and acceptable to researchers and lab environments.

There's about 600 fume cupboards at UNSW, maybe other unis will use this device in future if it proves effective in getting users to close the sash windows!