I have been searching for a used DigiQ DX2 or Rock's Stoker for a little while. The focus has been on a used unit because the $300 - $400 price tag for a new one just is not in the cards. In the meantime, I decided to build one from scratch. Given my pathetic electrical skills, I though I just may learn a few things along the way.
Like all projects of mine, it starts with multiple trips to home depot, radio shack, and a few visits from the UPS dude:
This is the brains of the system. It is controlled by a PID controller, which measures temperature and compares it to the target temp. If the measured temperature is lower than the desired value, it opens a relay which (in this case) drives a blower fan to stoke the coals. If the temperature is higher than the desired value, it shuts the fan off, reducing oxygen and as a result the temp falls. The system is programed to learn how fast your smoker temperature fluctuates and adjusts itself accordingly. I installed two switches - a main power switch (off/on), and an on-off-on switch. This capability is needed to compensate for big temp drops when I lift the lid, and also allows me to run the blower manually as well. The indicator light at the bottom right goes on when the fan is running.
Here is my motor set up. I need to do some finish work on it to make it look nice, but right now its functional. I decided to put a ball valve in so I can completely shut off the air into the smoker, thus saving some charcoal when I shut it down. I bought two fans as they were only $9. This one is rated to 10 CFM.
The air is directed right at the fire box. I plan to plug the other holes with some 1" metal plugs. This mounting position required no drilling in the SJP. I may add a diffuser to redirect the air down if needed. I can control the airflow by adjusting the fan, or by partially closing the ball valve:
I had to install a probe to measure the ambient temperature in the smoker. I chose to order a female K-type thermocouple unit and attached it to the PID. This allows me to use all of my existing thermoworks probes which saved quite a bit of money. Probes are not cheap! This one has an alligator clip installed on it so I can position the probe where I need to:
For power, I wanted to be able to plug the unit in the wall, but also wanted it to be portable. The system is 12V DC, so I bought a small ac to dc adaptor to plug in. Shown here is the portable option - a 12V battery that I had used to power an automatic door on my chicken coop. Since a bear ate the chickens, I no longer needed a chicken door
The fan and PID draw a total of 500 MA, so this battery would last about 16 hours with the fan running constantly. It should provide plenty of power for smoked pork butts!
The next step is to figure out a good installation spot on Wapiti's cart:
Hoping for a free day early next week to do a low and slow cook. With any luck at all, I can finally get some sleep on those overnight smoke sessions.
Winz