Reverse-Engineering a Wireless BBQ Thermometer

[Bob] has his own smoker and loves to barbecue, but doesn’t like spending all day checking on his smoker’s temperature. He thought about building his own wireless thermometer setup, which would have been pretty awesome, but then he had a better idea: why not hack an existing wireless barbecue thermometer? [Bob] purchased an off-the-shelf wireless BBQ thermometer and reverse-engineered its wireless protocol to make his own wireless thermometer setup.

The first problem [Bob] encountered was figuring out the frequency of the transmitter. Thankfully [Bob] had access to a spectrum analyzer, where he discovered the transmitter was running at 433.92MHz (a cheap RTL-SDR dongle would also get the job done). Next, [Bob] started digging into the manufacturer’s FCC filings and found that it actually called out the transmit frequency, which matched the transmit frequency he measured. He also found a ton of other helpful information in the filing, like a block diagram and full transmitter schematic.

[Bob] used a Radiometrix RF module to receive the thermometer’s signal. He hooked up the output to his logic analyzer to start decoding the protocol. After a quick visual analysis, [Bob] found that the signal was a preamble followed 13 bytes of Manchester-encoded data being transmitted at 2kbps. He started collecting data with known temperatures, created a table of the data, and began looking for patterns. After quite a bit of searching [Bob] was successfully able to find and parse the temperature values out of the data stream. [Bob] did a great job of documenting his process and results, so check out his writeup if you want to try it out yourself.

Custom heaters for a DIY BBQ smoker

Spring is in the air, and with that comes savory meals cooked over the course of dozens of hours. While preparing for your yearly allotment of pork and beef, check out [Brett Beauregard]’s custom heater elements he built for a DIY wood smoker.

This build follows the very successful smoker [Brett] built last year. This year, he’s using the same toaster oven heating elements, only cut down to make the heater smaller and more efficient. Basically, [Brett] is making a small cartridge heater out of the equipment he already has.

After cutting the toaster oven heating elements to length, [Brett] reamed out the ends to expose the nichrome wire. A short hit with a TIG welder bonded the lead to the heating element. Insulated with furnace cement, [Brett] had a custom heater perfect for charring chunks of mesquite or hickory.

Meat smokers aren’t very complicated – they can be built with a flowerpot and a hotplate, and will still cook up a delicious dinner. We might have to borrow [Brett]’s technique when we build this year’s smoker.

Mini-cannon built from a BBQ lighter fires Airsoft pellets

[Nighthawkinlight] has made his own palm cannon to shoot Airsoft pellets. His process, which he guides us through step-by-step in the video after the break, definitely invokes MacGyver buy using commonly available parts in a way they were not intended.

He starts with a barbecue lighter, removing the screws and plastic housing to get at the clear plastic butane reservoir which serves as the body of the cannon. The butane is carefully released from the tank, and the output valve is modified to receive the barrel. In this case the barrel from an old Airsoft gun was used, but a metal pen housing could do the trick as well. The spark igniter from the lighter is also reused, but two bolts have been screwed into the reservoir and are used as probes for the igniter wires. In order to fire this one-shot-wonder, a cotton swab soaked in 90% alcohol is inserted through the bolt on the left side. After inserting an Airsoft pellet the trigger is pulled to ignite the vapors.

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