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November 6, 2006
about 7 years ago
The type I've used (stone age vintage, but they look the same) in good working order had the heatsink (bottom metal plate) insulated from everything.
The caveat to that, though, is if/when they fail due to overheating (see dnear1's post) is that you can't tell what's going to be connected to what after meltdown (literally for me, in one case several years ago).
In that particular case, nothing in the controller circuit got damaged, but I did measure several megohms resistance between the control inputs and the AC inputs (and shorted AC output) after meltdown. I chalked it up to carbonized plastic. May or may not be worth keeping in mind for your circuit.
Your post implies you've used these before.
For those curious about "failure modes", my experience is that when they fail (due to overheating), they fail in the "closed" (ON) position -- i.e. the triac shorts. I generally calculate the load current and multiply that by two, and then use a heat sink anyway.
One thing I always look for, though, is the "zero cross" switch. That's particularly important if you're trying to control something like a hot plate, which invites a huge current surge when switched on as the input AC approaches a peak value.
about 7 years ago
This observation might be 3 years late, but although the Due (and other ARM boards) are screaming fast and have tons of I/O and memory, they consume about 30x as much current.
That's worth knowing if you're intending to build a battery product.
I've been comparing the Teensy products with the Mega Pro, and for my intentions it comes down to whether I can afford 30 mA drain on a standalone battery with the Teensy vs the 3-5 mA on a board like this. Add in a Zigbee module to your project, and you have potentially serious battery life issues.
No public wish lists :(