[TriEmbed] Coffee roaster sanity check

[Brian]

Another just-before-bed correction to make on your last schematic 
update, where you reacted to this piece of advice:

 >> It may be wise to have a series resistance between the Arduino and
 >> the SSR's control pin.  250 ohms would be a good value to use here as
 >> well.
 >
 > Updated now.

I might have been too terse in describing what I meant.  The 10k pulling 
the SSR input to GND should stay, and a 250-ohm resistor should go 
between the SSR input and the Arduino pin:

               250
UNO_PIN>-----/\/\/\---+----------<SSR_IN
                       |
                       +---/\/\/\----<GND
                            10k

This way, if something goes bad inside the SSR and shorts its input to 
ground, or it has a large capacitance, the 250-ohm resistor will limit 
the current flowing out of the Uno (the exact same configuration and 
reasoning for the MOSFET gate).

Happy 2020!
-B
<snip>