Wulf's Webden

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Circuit Design

I have been making further strides with my thermonitor project. I’ve purchased a second temperature sensor and have established that I can connect and read from both. The next step is to come up with a better housing than being cobbled together on a breadboard and so I have been developing my skills to facilitate this.

The first step was to think about the best way of wiring the the sensors in and I settled on 3.5mm stereo jack plugs. To connect the circuit to the Raspberry Pi, I have a little breakout board and that will fit some header strips I bought. I also have a long piece of stripboard, but what would be the ideal way to wire it all up? How about:

Circuit Design

Thermonitor Breakout Box

That is my working design. The input wires link to pins on the Pi – white for GPIO4 (carrying the data), red for 3.3V power and black for ground. The wires colours on the board represent the jumper leads I expect to use (based on the length required). Ideally I would stick to the white / red / black scheme but haven’t built up a sufficient parts collection to do that yet. Given that the circuit is very simple, I think it won’t be a problem in this case. The ground is collected to the sleeve, the power to the ring and the data to the tip, with power and data being bridged by a 4.7K resistor.

This weekend, I will see if I can manage to turn this diagram into a reality and then, once it works, mount it inside the box. If everything workds well, I will have a neat solution to use for further testing of my software and in readiness for my next homebrewing project.

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