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MAKE: PROJECTS Eccentric Cubicle Figure 09.65: I'll admit it: I love doing physical user interfaces. The lamp sockets are screw-mounted, with rubber isola- tion gaskets to prevent any potential shock hazards. For ease of assembly, I ran the entire control console wiring har- ness out through the bottom of the coffee pot and through the base of the mechanism, with the actual electrical con- nections to the subassemblies occurring via wire nut con- nectors "in the basement." [Figure 09.69] Instrumentation As mentioned, there's always room for dials, gauges and readouts on a fogger. The digitally inclined among you will doubtless proceed with an Arduino or Make controller board­based solution to monitor and control air flow, hotbox temperature, fog juice level, and feed rate and intercooler in/ out temperature gradient. Me, I grabbed a dollar-store meat thermometer and a scrap-yard pressure gauge and bunged them into the mechanism via the ultimately elegant-in-its- simplicity Brute Force method. Monitoring the hotbox temperature (in particular, the surface temperature of your hot plate) is a good idea; glyc- erin starts denaturing into nasty 'aldehydes at around 400 degrees C. The operating temperature for a fogger is depen- dent on the fog juice in use. In the case of a simple water/ glycerin blend, the higher the percentage of glycerin, the higher the required operation temperature. Glycerin flashes at 290 degrees C. Consider that to be the top end of your safe operational range, with 100 degrees C as the lower limit. A cheap-ass dollar-store meat thermometer works via a bimetallic coil that winds/unwinds in relation to temperature due to the differing thermal expansion/contraction factors of the two metals. This means figuring out a way to transfer the heat of the hot plate to the long pointy probe, which would be entering through the side of the hotbox at a 45-degree angle. [Figure 09.70] 286