Temperature window over-limit alarm circuit (MAX6502/4)

As shown in the figure, the circuit is composed of an upper and lower limit temperature detection circuit, a voice sound circuit, an audio power amplifier circuit and an AC step-down rectifier circuit. The upper temperature limit monitor is monitored by the temperature switch integrated circuit MAX6502, which converts the temperature of the monitored object into a corresponding electrical signal. When the signal voltage exceeds the set threshold temperature (for example, 55oC), the voltage in the temperature switch is After comparison and judgment, the monostable trigger outputs a shaping pulse, and the push-pull output stage outputs a high-level control signal. This signal is added to the trigger terminal TG of the sound circuit IC3 via VD1, causing it to trigger sound.