I have this insane idea to make one of those coffee warmers turn off after a while. So your coffee won't evaporate and the warmer cook the sludge to glass on the bottom of your cup.
Not having a lot of room in the innards of the warmer - parts count becomes the limiting factor. Should be doable with a surface mount tiny2313 running on its internal clock, driving a sensitive gate triac, and a transformerless power supply. No opto-isolators will be necessary since the whole circuit will be hot, literally. Wonder what the temperature specs are on the AVR?
I found a nice APP note @ Microchip -Transformerless Power Supplies: Resistive and Capacitive with a couple of suitable power supply circuits. The capacitor circuit looked a little more inviting - if a little pricier - 10w resistors tend to be BIG.
So the first hurdle surmounted. Now all I have to do is get the Microcontroller circuit found - Any ideas?
DISCLAIMER! Not advised for the first timer, if you mess up working with this kind of circuit your coffee cup won't be the only thing cooked - you'll just be dead. And your Mom will complain about that horrible stink from little Johny's shop. So don't blame me.
Lenore on Meet a Maker
4 days ago