CN-224202602-U - Thermal alarm circuit for detecting resistance value

Abstract

The utility model discloses a power supply resistance detection type thermal alarm circuit which comprises a power supply circuit, a control circuit, a temperature detection circuit and an alarm circuit, wherein the power supply circuit comprises a power supply reverse connection prevention module and a resistance detection module, the output end of the power supply reverse connection prevention module is connected to the input end of the resistance detection module, the output end of the resistance detection module is connected to the first input end of the control circuit, the control end of the resistance detection module is connected to the first output end of the control circuit, the output end of the power supply reverse connection prevention module supplies power to the power supply end of the control circuit, the PWM output end of the control circuit is connected to the power supply end of the temperature detection circuit, the output end of the temperature detection circuit is connected to the second input end of the control circuit, the output end of the power supply reverse connection prevention module supplies power to the power supply end of the alarm circuit, and the control end of the alarm circuit is connected to the second output end of the control circuit. The power supply resistance detection type thermal alarm circuit solves the problem that the resistance of a power supply circuit cannot be detected in the prior art.

Inventors

• LIN CHAO
• CHEN ZHENGXIN

Assignees

• 重庆卓雷科技有限公司

Dates

Publication Date

20260505

Application Date

20250702

Claims (7)

1. 1. The resistance value detection type thermal alarm circuit is characterized by comprising a power supply circuit, a control circuit, a temperature detection circuit and an alarm circuit; The power supply circuit comprises a power supply reverse connection prevention module and a resistance value detection module, wherein the input end of the power supply reverse connection prevention module is connected to a power supply, the output end of the power supply reverse connection prevention module is connected to the input end of the resistance value detection module, the output end of the resistance value detection module is connected to the first input end of the control circuit, and the control end of the resistance value detection module is connected to the first output end of the control circuit; the output end of the power supply reverse connection prevention module supplies power to the power supply end of the control circuit, the PWM output end of the control circuit is connected to the power supply end of the temperature detection circuit, and the output end of the temperature detection circuit is connected to the second input end of the control circuit; The output end of the power supply reverse connection preventing module supplies power to the power supply end of the alarm circuit, and the control end of the alarm circuit is connected to the second output end of the control circuit.
2. 2. The circuit for the resistance value detection type thermal alarm device according to claim 1, wherein the resistance value detection module comprises a constant load unit and a control access type load unit, the high-voltage end of the constant load unit is connected with the high-voltage end of the control access type load unit, the output end arranged in the middle of the constant load unit is the output end of the resistance value detection module, the high-voltage end of the control access type load unit is connected to the output end of the power supply inverse connection prevention module, the low-voltage end of the constant load unit and the low-voltage end of the control access type load unit are grounded, and the control end of the control access type load unit is the control end of the resistance value detection module.
3. 3. The circuit of claim 2, wherein the control access type load unit comprises an NPN triode Q2, an NPN triode Q3, a resistor R2 and a resistor R3, wherein a base electrode of the NPN triode Q2 is connected to a first end of the resistor R2 and a collector electrode of the NPN triode Q, a second end of the resistor R2 is a control end of the control access type load unit, a collector electrode of the NPN triode Q2 is a high voltage end of the control access type load unit, an emitter electrode of the NPN triode Q2 is connected with the first end of the resistor R3, and a second end of the resistor R3 and an emitter electrode of the NPN triode Q3 are connected to form a low voltage end of the control access type load unit.
4. 4. The circuit for a resistance value detection type thermal alarm according to claim 3, wherein the constant load unit comprises a resistor R4 and a capacitor C3, the first end of the resistor R4 is a high voltage end of the constant load unit, the second end of the resistor R4 is connected to the positive electrode of the capacitor C3, the negative electrode of the capacitor C3 is a low voltage end of the constant load unit, and the positive electrode of the capacitor C3 is an output end of the resistance value detection module.
5. 5. The circuit of any one of claims 1 to 4, wherein the power supply reverse connection preventing module comprises a PMOS tube Q1, a capacitor C1 and a resistor R1, wherein the drain electrode of the PMOS tube Q1 is connected to the positive electrode of the capacitor C1, the positive electrode of the capacitor C1 is an input end of the power supply reverse connection preventing module, the grid electrode of the PMOS tube Q1 is connected to the first end of the resistor R1, the second end of the resistor R1 and the negative electrode of the capacitor C1 are grounded, and the source electrode of the PMOS tube Q1 is an output end of the power supply reverse connection preventing module.
6. 6. The circuit of claim 5, wherein the temperature detecting circuit comprises a thermistor RT1, a resistor R5 and a capacitor C2, the first end of the thermistor RT1 is the power supply end of the temperature detecting circuit, the second end of the thermistor RT1 is the output end of the temperature detecting circuit, the second end of the thermistor RT1 is connected to the first end of the resistor R5 and the positive electrode of the capacitor C2, and the second end of the resistor R5 and the negative electrode of the capacitor C3 are grounded.
7. 7. The circuit for detecting a resistance value of a thermal alarm according to claim 6, wherein the alarm circuit comprises a buzzer BZ1, an inductor L1, a diode D1, an NPN triode Q4 and a resistor R6, wherein the positive pole of the buzzer BZ1 is a power supply end of the alarm circuit, the positive pole of the buzzer BZ1 is connected to a first coil end of the inductor L1, the negative pole of the buzzer BZ1 is connected to a second coil end of the inductor L1, the middle of the coil of the inductor L1 is connected to the cathode of the diode and the collector of the NPN triode Q4, the anode of the diode and the emitter of the NPN triode Q4 are grounded, the base of the NPN triode Q4 is connected to a first resistor R6, and the second end of the resistor R6 is a control end of the alarm circuit.

Description

Thermal alarm circuit for detecting resistance value Technical Field The utility model relates to the field of temperature alarms, in particular to a power supply resistance detection type thermal alarm circuit. Background The thermal alarm is a temperature alarm, so that the temperature is detected, and the alarm is realized when the temperature is too high. The Chinese patent discloses a methane temperature alarm with the application number of CN202323627069.0, which comprises an upper shell, a lower shell, an induction execution assembly and an alarm device, wherein the upper shell and the lower shell are buckled to form a cavity, the induction execution assembly and the alarm device are arranged in the cavity, the induction execution assembly comprises a starting switch, a detection control circuit and a sensor device, the sensor device comprises a methane sensor and a temperature sensor, the methane sensor is used for detecting environmental methane, the temperature sensor is used for detecting the temperature of rhizoma polygonati, the detection control circuit is arranged on a circuit board, the detection control circuit comprises an amplifying module, an analog-to-digital conversion chip U3 and a controller U1, and the output end of the methane sensor is connected with the input end of the amplifying module. The methane temperature alarm can realize temperature monitoring, but has the defect that the methane temperature alarm can not realize detection of the resistance value of a power supply circuit, so that the current of the power supply circuit can not be known, and the current at a temperature sensing part is easy to flow little to influence the detection result. Disclosure of utility model The utility model provides a thermal alarm circuit for detecting a resistance value, which solves the problem that the resistance value of a power supply circuit cannot be detected in the prior art. In order to achieve the above purpose, the present utility model adopts the following technical scheme: The utility model discloses a power supply resistance detection type thermal alarm circuit which comprises a power supply circuit, a control circuit, a temperature detection circuit and an alarm circuit, wherein the power supply circuit comprises a power supply reverse connection prevention module and a resistance detection module, the input end of the power supply reverse connection prevention module is connected to a power supply, the output end of the power supply reverse connection prevention module is connected to the input end of the resistance detection module, the output end of the resistance detection module is connected to a first input end of the control circuit, the control end of the resistance detection module is connected to a first output end of the control circuit, the output end of the power supply reverse connection prevention module supplies power to the power supply end of the control circuit, the PWM output end of the control circuit is connected to the power supply end of the temperature detection circuit, the output end of the temperature detection circuit is connected to a second input end of the control circuit, the output end of the power supply reverse connection prevention module supplies power to the power supply end of the alarm circuit, and the control end of the alarm circuit is connected to a second output end of the control circuit. Preferably, the resistance value detection module comprises a constant load unit and a control access type load unit, wherein the high-voltage end of the constant load unit is connected with the high-voltage end of the control access type load unit, the output end arranged in the middle of the constant load unit is the output end of the resistance value detection module, the high-voltage end of the control access type load unit is connected to the output end of the power supply reverse connection prevention module, the low-voltage end of the constant load unit and the low-voltage end of the control access type load unit are grounded, and the control end of the control access type load unit is the control end of the resistance value detection module. Preferably, the control access type load unit comprises an NPN triode Q2, an NPN triode Q3, a resistor R2 and a resistor R3, wherein the base electrode of the NPN triode Q2 is connected to the first end of the resistor R2 and the collector electrode of the NPN triode Q, the second end of the resistor R2 is a control end of the control access type load unit, the collector electrode of the NPN triode Q2 is a high-voltage end of the control access type load unit, the emitter electrode of the NPN triode Q2 is connected with the first end of the resistor R3, and the second end of the resistor R3 and the emitter electrode of the NPN triode Q3 are connected to form a low-voltage end of the control access type load unit. Preferably, the constant load unit comprises a resistor R4 and a capacitor C3, wherein the