Title: Temperature-responsive alarm control circuit

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Abstract: Solid-state circuitry is provided for an electrical thermometer for monitoring the interior temperature of food being cooked. A temperature sensing thermistor located in the tip of a probe, adapted to be partially inserted in food being cooked so as to monitor the interior temperature, is combined in circuit with a programmable unijunction transistor (PUT), used as a bridge threshold detector, an NPN transistor-diode load current switch and a buzzer alarm coil such that upon the reaching of a preset temperature within the food, the buzzer alarm is actuated. The self-heat of the thermistor probe provides a latching effect ensuring the continued firing of the PUT with the resultant smooth operation of the buzzer alarm. A resistor is combined in circuit to allow a slight back current to flow through the buzzer coil, thereby allowing the use of a buzzer alarm with a fairly non-critical air gap.


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