28 June 2015
If you’ve ever had a freezer malfunction with hundreds of dollars’ worth
of meat rotting in it, you know what a disaster it can be. Not only is there
the expense of the loss of the contents, but the smell and the cleaning is
something you will never forget. Many of us have freezers in sheds, barns,
and external garages. We never would know until the smell waifs through our
nostrils if the power or compressor goes out.
By Ron Newton
The transmitter unit uses a Linx TXM 418 long range
transmitter and a Microchip PIC12F675 for control.
This chip has an analog-to-digital converter (ADC). The
chip also provides 28 transmission codes, so if there are
several transmitters in the area, they won’t trip other
people’s alarms. The assembly code for both the receiver
and transmitter, ExpressPCB board files, schematics,
parts source, and other Hints and Tips are available
at the article link. If you don’t have a programmer,
BUILD A WIRELESS FREEZER
BUILD IT YOURSELF
28 June 2015
This is a wireless device that performs two
functions. It alarms if the power is disconnected
or a circuit breaker trips, and it constantly
measures the internal temperature of the freezer.
It will sound the alarm if the temperature exceeds
- 15°C (or about 0°F). The temperature can be set
to alarm at any temperature you require. The Linx
transmitter is capable of transmitting up to 3,000
feet, depending on what is in its path.