Fermentation Control Board

I wired all the components from a schematic I made. Took a few steps to get to the finished product. Below is a circuit demonstrating the concept and it incorporates a few things.

• A power jack
• NPN Transistor
• Peltier Device
• Digital temperature sensor
• x2 Fans
• One to cool the heat sink
• One to circulate the chamber

The Raspberry Pi reads the temperature and switches the MOSFET from another GPIO pin. The x2 fans and Peltier device are all on the same MOSFET since they need to turn on at the same time.

Schematic of Diagram

I ended up with a large power block that operates at 12 V and is capable up to 10 Amps. The Peltier can pull up to 5 A and the fans about 1 A and the Raspberry Pi another amp probably. My goal was to power everything from one source so I didn't have all these power cords and I could easily mount it to the top of the cooler. Due to the large current draw on some components, I didn't design a PCB board for this. Instead I went with a perfboard. All the components are 12 V except for the Raspberry pi so to power that, I purchased a small buck power converter for a few bucks on Amazon. It works very well and steps down the 12V to 5V and the raspberry pi can be powered via USB then. I mounted this directly to the board itself.

I laid it out on a piece of "perfboard paper" which makes it very easy to plan how to mount the components. If you Google for it you can find it easily online. I drew the layout some-what to scale on the size board I was using and labeled everything.

Perfboard Layout on Piece of Paper

After I laid everything out on the board, I went ahead and wired the components with wires on the bottom. I used lower gauge wire for higher amp lines and just used some 22 gauge for the smaller stuff. Pins on the left hook to Raspberry Pi and I have 3 terminals.

• Temp Sensor Terminal
• Fan and Peltier Terminal
• Power Terminal

Wired Perf Contorl Board

After I confirm all connections, I'll go ahead and test it out!