KR19990000686U - Constant Temperature Fire Detector Circuit - Google Patents

Abstract

The present invention relates to a fire detector, and more particularly, to a constant temperature fire detector circuit suitable for detecting a fire in a place where flammable gas or a high temperature is not generated by a spark. The present invention provides a bridge circuit (BD) for applying a predetermined voltage to the circuit, an LED for indicating whether the voltage from the bridge circuit is applied stably, a zener diode (ZD) for applying a constant voltage to the circuit, The diode D1 for sensing the temperature, the resistors R5 and R6 for configuring the voltage distribution circuit and applying the reference voltage to the gate of the PUT, and the anode of the PUT according to the current generated by the diode D1. Resistors R7 and R8 for applying a temperature sensing voltage, a reference voltage (gate voltage of the PUT) generated by the resistors R5 and R6, and a temperature sensing voltage generated by the diode D1 A PUT for comparing the anode voltage of the PUT and outputting the output value to the thyristor (SCR), and a thyristor (SCR) for generating a fire alarm based on the value output from the PUT. Fire detection A circuit.

Description

Constant Temperature Fire Detector Circuit

The present invention relates to a fire detector, and more particularly to a constant temperature fire detector circuit suitable for detecting a fire in the presence of flammable material or high temperature by generating no spark.

In the presence of flammable materials, even a small spark can cause a sufficient fire. In addition, when the surrounding environment is a high temperature there was a problem that the circuit does not operate properly.

The present invention is designed to monitor fires without causing sparks in the presence of flammable materials and when the environment is hot. In addition, it is designed to reduce the price of the fire detector by constructing a circuit with fewer parts, and it is also designed to be fast and reliable.

1 is a circuit diagram showing a first embodiment of the present invention.

2 is a circuit diagram showing a second embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings *

R2. R3, R4, R5, R6, R7, R8. Resistors C1, C2, C3, C4. Condenser

SCR. Thyristor D1. diode

ZD. Zener Diodes BD. Bridge circuit

TH1. Dummyster

Referring to Figure 1 the configuration of the first embodiment of the present invention as follows.

A predetermined voltage is applied to the input of the bridge circuit BD, and an LED, which is an operation indicator, is connected to the output of the bridge circuit. One end of the capacitor C1, the anode of the thyristor SCR, and one end of the resistor R2 are respectively connected to the output terminal of the LED. The resistors R5 and R6 connected in series and the capacitor are connected in parallel and connected to the other end of the resistor R2. The resistor R5 is connected to the collector of the transistor Q1, the cathode of the diode D1, and the cathode of the zener diode ZD. The anode of the diode D1 and the base of the transistor Q1 are connected to each other and are connected to the resistors R7 and R8 connected in series. An emitter of the transistor Q1, a capacitor C4, and an anode of the PUT are connected between the resistor R7 and the resistor R8 connected in series. The gate of the PUT is connected between a resistor R5 and a resistor R6 connected in series. The cathode of the PUT is connected to a capacitor C2 and a resistor R4 connected in parallel via a resistor R3, and the capacitor C2 and a resistor R4 connected in parallel are connected to a gate of the thyristor SCR. . A capacitor C2, a resistor R4, a capacitor C3, a resistor R6, a PUT cathode, a capacitor C4, a resistor R8, and a zener diode ZD connected in parallel with the cathode of the thyristor SCR. Anodes are connected to each other.

Referring to Figure 1 describes the operation of the first embodiment of the present invention.

A predetermined voltage (for example, DC24 [V]) is applied to the input terminal of the bridge circuit BD to supply power to the circuit. The capacitor C1 and the resistor R1 operate as a resonant circuit, and the capacitor C1 alone operates as a smoothing capacitor for removing power supply noise. The voltage applied through the bridge circuit BD is divided between the resistor R5 and the resistor R6, and the voltage divided by the resistor R6 forms the gate voltage of the PUT. At this time, the voltage applied to the resistor R6 may be adjusted by adjusting the resistance values of the resistors R5 and R6, and the adjusted voltage is referred to as a reference voltage (gate voltage of the PUT) as a reference for fire occurrence. Is set to. Here, the PUT is a device that operates when the voltage of the anode is higher than the voltage of the gate by a predetermined value (for example, about 0.6 [V]).

Here, the diode D1 is used as a device for sensing heat by using a characteristic in which the reverse current of the diode D1 changes with temperature. That is, in normal cases, little current flows through the diode D1, but when the temperature rises, a small amount of reverse current flows. If a fire occurs and the ambient temperature increases, the transistor Q1 becomes conductive when the reverse current of the diode D1 increases and exceeds a predetermined value. When the transistor Q1 becomes conductive, the capacitor C4 starts to charge, and a voltage is applied to the anode of the PUT. The PUT compares the voltage applied to the PUT's anode with a preset reference voltage applied to the PUT's gate, so that the PUT conducts when the anode's voltage is higher than the gate's voltage. When the PUT conducts, current flows through the gate of the thyristor SCR, and when current flows through the gate of the thyristor SCR, the thyristor SCR conducts and fires an alarm.

In addition, the voltage applied to the anode of the PUT can be adjusted by changing the resistance value of the resistor R7. Therefore, simply changing the resistance value of the resistor R7 adjusts the temperature operating point of the circuit (the temperature at which the voltage of the anode of the PUT is higher than the gate voltage of the PUT so that the thyristor SCR conducts and emits a fire alarm). It is possible.

Now, a second embodiment of the present invention will be described with reference to FIG.

The second embodiment of the present invention is almost the same except that the dummyster TH1 is used instead of the diode D1 in the first embodiment. The basic operation of the second embodiment is as follows.

The voltage is divided by the resistor R5 and the resistor R6, and the voltage divided by the resistor R6 forms the gate voltage of the PUT, and this gate voltage becomes the reference voltage. At this time, when the ambient temperature rises due to a fire or the like, the resistance value of the dummyster TH1 increases, and the anode voltage of the PUT increases due to the increased resistance value. If the anode voltage of the PUT is higher than the gate voltage of the PUT by a predetermined value or more, the PUT is operated, and when the PUT is operated, the thyristor SCR is operated to generate a fire alarm.

Since the diode D1 can operate at a high temperature and does not generate a spark, when the diode D1 is used as a sensor, it can be used in any place. In addition, since the diode D1 is sensitive to temperature, a fast response speed can be obtained. In addition, since the price of the diode D1 is low, the cost of the entire circuit is low, and the characteristics of the diode D1 are well known and easy to adjust, thereby improving reliability.

By using the PUT, the reference voltage and the temperature sensing voltage can be easily compared and the thyristor can be turned on, so that two functions can be performed by one element, thereby simplifying the overall circuit and reducing the cost. have. In addition, since it is possible to adjust the temperature operating point of the circuit simply by changing the resistance value of the resistor R7, it is easy to set the characteristics according to the surrounding environment.

As described above, in order to detect a fire where a fire easily occurs even in a small spark, since the circuit is configured to not generate a spark, the fire detector can be installed in a place where flammable materials are present. It may also be used as a fire detector circuit for fire detection in general places such as homes or offices.

Claims (3)

In the constant temperature fire detector circuit, A bridge circuit BD for applying a predetermined voltage to the circuit, LED for indicating the operation status of the fire detector, Zener diode (ZD) for applying a constant voltage to the circuit, A diode D1 for sensing temperature, Resistors (R5, R6) for constructing a voltage distribution circuit and applying a reference voltage to the gate of the PUT; Resistors R7 and R8 for applying a temperature sensing voltage to the anode of the PUT according to the current generated in the diode D1; The output value is output to the thyristor SCR by comparing the reference voltage generated by the resistors R5 and R6 (the gate voltage of the PUT) with the temperature sensing voltage generated by the diode D1 (the anode voltage of the PUT). PUT to do, And a thyristor (SCR) configured to emit a fire alarm based on the value output from the PUT. The method of claim 1, The constant temperature fire detector circuit, characterized in that the dummy (TH1) can be used in place of the diode (D1) that performs the function of sensing the temperature. The method of claim 1, And a temperature operating point can be changed by changing a resistance value of the resistor (R6).