Why pop-up toasters know when to stop

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Inside, electric current flows through the heating elements, turning them red hot and sending heat toward the bread.<sup class="text_citation" source_id="9"></sup><sup class="text_citation" source_id="3"></sup>

Older toasters often use a bimetal strip or thermostat, while some newer models use a timer, capacitor, or sensor-based control to decide when the cycle ends.<sup class="text_citation" source_id="3"></sup><sup class="text_citation" source_id="6"></sup><sup class="text_citation" source_id="16"></sup><sup class="text_citation" source_id="19"></sup>

At the same moment, a latch holds the carriage down against a spring, and when the mechanism releases, the spring pops the toast up.<sup class="text_citation" source_id="4"></sup><sup class="text_citation" source_id="13"></sup><sup class="text_citation" source_id="26"></sup>

If the lever will not stay down, crumbs or dirty contacts can be part of the problem, so a careful clean is the simplest doneness tip to try first.<sup class="text_citation" source_id="1"></sup><sup class="text_citation" source_id="5"></sup><sup class="text_citation" source_id="28"></sup>