A very simple toaster oven costs about $20. While the most consumer electrical appliances have microcontrollers inside and some are internet connected; this oven is pretty much mechanically controlled. It has two quartz heating elements, 500W each (measured around 4.5A each), at the top and the bottom. The cold resistance is about 14 Ohms; Over 17A is drawn initially. A spring winded mechanical timer sets time up to 30min or staying on. The timer is more or less accurate. The mechanical timer switches the live AC wire.
The neural wire goes to the temperature control knob, which turns to set the temperature up to 450F in the toast mode, which both heat elements are on; the turning just pushes a spring loaded switch. Turning further to the bake and the broil mode to turn on only the bottom and the top respectively; no temperature control in these two modes. The temperature is controlled by a heat activated switch. It does not actually sense the oven temperature, instead a current passes through a metal strip, which can be seen glow red; the heat bends a nearby bimetal strip to actuate the switch. There is no earth ground connection; that seems risky if the AC wire is shorted to the chassis.
How would this design compare with a more electronically controlled design in cost and reliability?
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