經濟部中央標準局貝工消費合作社印製 4-6206 4538twf,d〇〇/006 B7 五、發明説明（丨） 本發明是有關於一種電路保護裝置，且特別是有關 於一種應用於電話線上之保護裝置。 由於科技的日新月異，人與人之間的互動更加頻繁， 電話、傳真機、數據機以及其他應用於電話線上的電器， 逐漸成爲我們日常生活中不可或缺的工具，然而 Ί 當電話線接頭誤插入整合服務數位網路（Integrated Services Digital Network > ISDN )插頭、或者交換機（Private Brandi Exchange，PBX)故障、或者是電信局的電話線路故障時， 此時在電話線上會有異常的高電壓以及大電流產生，會造 成電話線上的電器毀損。請參閱第1圖，其所繪式爲習知 電話線之保護裝置，其電話線是由插座40接出，並且電 話線連接的動作是依據傳真/數據機控制器12送訊號至掛 勾開關電路14來連結電話線，而該保護裝置是在傳真/數 據機的電話線上串聯保險絲（Fuse)或者多晶矽開關（P〇ly Switch) 10，用來防止電話線上之過電壓或者過電流的通 過’造成電話線上的傳真/數據機毀損，而該保護裝置之缺 點爲大電流會將保險絲或者多晶矽開關燒毀，必須重新再 裝上新的保險絲或者多晶矽開關，才能使傳真/數據機恢復 正常動作’實用上非常不方便；而在歐洲規格更限定傳真/ 數據機的電路中一定要有電流限制（Current Limit)電路_ 20 ’但是若電路中有電流限制電路20，當過電流產生時電 流會被此電流限制電路20限定在一固定値內，然而此阖 定値電流會使電晶體組30因溫度或電壓過高而燒毀，或 者讓機殼溫度過高而燒毀，並不能夠真正做到電流以及路 3 本:紙張用中( CNS ) 21()><297公兼） I I— :—11 參 — 訂 I 1 線 (請先閱讀背面之注意事項再填寫本頁) 經濟部中失標準局員工消费合作杜印裝 416206 4538twf.doc/006 A7 ___B7_ 五、發明説明（\) 壓保護的功能。 因此本發明係提出一種應用於電話線上之保護裝 置’在電話線路上的資料存取安排（Data Access ArnuigemeiU ’ DAA)線路內加上保護裝置，當電話線上出 現不正常的過電壓或者過電流信號時，過載偵測電路會偵 測到此過電壓或者過電流’並且送出過載信號給強制掛上 勾（On Hook)電路；或者當電話線上出現不正常的溫度 升高時，高溫偵測電路會偵測到此溫度的變化，並且送出 筒溫信號給強制掛上勾電路，當強制掛上勾電路接收到過 載信號或者高溫信號，會將掛勾開關（H〇〇k Swiich)掛上 勾，當電話線被掛上勾，由於傳真/數據機之驅動程式會發 現電話線上無載波，會迫使DAA線路確實掛上勾，因而 可防止零件因高電壓或高溫而燒毁，達到保護電路的目 的。 本發明係提出一種應用於電話線上之保護裝置，能 夠快速的偵測到電話線上的異常狀況，並且將電話線掛上 勾，達到保護電路的目的。 本發明提出一種應用於電話線上之保護裝置，其簡 述如下： 一種應用於電話線上之過電壓以及過電流保護裝 置，親接於電話線，包括： 橋式整流器’以電話線作爲該橋式整流器之輸入端 並且並聯於電話線，並以電話線上之電話線電壓作爲橋式 整流器之輸入，將電話線電壓整流爲整流電壓，送至該橋 4 本紙浪尺度適用中國國家梂準（CNS ) Α4規格（2Ι0Χ297公釐） I 1^------ΪΤ------Μ (請先聞讀背面之注意事項再填寫本頁} 經濟部中央標準局員工消费合作社印製 416206 ' 4538twf.doc/006 A7 B7 五、發明説明（3>) 式整流器之輸出端。過載偵測電路，耦接至橋式整流器之 輸出端，用來接收整流電壓，且當整流電壓超過預設値時， 送出過載信號。強制掛上勾電路，耦接至過載偵測電路， 並依據過載信號與掛下勾信號，產生掛上勾信號。掛勾開 關電路，耦接於強制掛上勾電路並且串聯於電話線，用來 根據所接收之掛下勾信號做出電話線之掛下勾動作。 一種應用於傳真/數據機之保護裝置，用以保護傳真/ 數據機電路免於過熱，該保護裝置包括： 偵測電路，用以偵測傳真/數據機電路的溫度，當溫 度超過預設値時，送出過載信號。強制掛上勾電路，耦接 至偵測電路，並依據過載信號與掛下勾信號，產生掛上勾 信號。掛勾開關電路，耦接於強制掛上勾電路並且串聯於 電話線，用以根據所接收之掛下勾信號做出電話線之掛下 勾動作。 爲讓本發明之上述目的、特徵、和優點能更明顯易 懂，下文特舉較佳實施例，並配合所附圖式，作詳細說明 如下： 圖式之簡單說明： 第1圖其所繪式爲習知電話線之保護以及電流限制電 路； 第2圖其所繪示爲本發明應用於電話線上之過電壓以 及過電流保護裝置方塊圖； 第3圖其所繪示爲本發明應用於電話線上之過電壓以 及過電流保護裝置電路圖；以及 5 本紙張尺度逋用中國國家橾牟（CNS ) A4规格（210X297公釐） n nn n ^ (請先閱讀背面之注項再填寫本頁〕 4538twf.doc/006 A7 B7 經濟部中央標準局員工消費合作社印^ 五、發明説明（if ) 第4圖其所繪示爲本發明應用於電話線上之高溫保護 裝置電路圖。 標號說明： 10保險絲或者多晶矽開關 12傳真/數據機控制器 14掛勾開關電路 20電流限制電路 30電晶體組 40插座 50橋式整流器 60插座 100過載偵測電路 200強制掛上勾電路 300掛勾開關電路 400傳真/數據機控制器 700偵測電路（熱敏電阻） 900電流限制電路 910電晶體組 實施例 請參照第2圖，其所繪示爲本發明應用於傳真/數據 機電話線上之過電壓以及過電流保護裝置方塊圖。電話線 由插座60接出，將橋式整流器50的a、b節點爲輸入端， 接至電話線上，電話線上之電話線電壓ν,會經過橋式整 流器50整流1形成整流電壓V2，並以橋式整流器50的c、 6 本紙張尺度適用中國國家標準（CNS^ A4規格（210X 297公釐Γ " ------------^------1T------.^ (請先閱讀背面之注意事項再填寫本頁) 經濟部中央標準局員工消費合作杜印製 416206 4538twf.d〇c/006 ._ A7 B7 五、發明説明（$ ) d節點爲輸入端，送至過載偵測電路100。以橋式整流器50 的a、b節點爲輸入端，然而當電話線接頭誤插入整合服 務數位網路插頭、或者交換機故障、或者是電信局的電話 線路故障時，此時在電話線上會有異常的高電壓以及大電 流產生，當電話線上出現異常高的電話線電壓時，經由橋 式整流器50，過載偵測電路100根據整流電壓判斷出電話 線上有異常高的電話線電壓，此時，過載偵測電路100會 送出過載信號給強制掛上勾電路_ 200，當強制掛上勾電路 200接收到過載信號，會將來自傳真/數據機控制器400的 掛下勾信號更改爲掛上勾信號。依照本實施例，掛勾開關 電路300是由一繼電器（Relay )所組成，當掛下勾信號送 至掛勾開關電路300時，此掛勾開關電路300會將電話線 連接起來，當掛上勾信號送至掛勾開關電路300時，此掛 勾開關電路300會將電話線切斷。 請參照第3圖，其所繪示爲本發明應用於傳真/數據 機電話線上之過電壓以及過電流保護裝置電路圖。依照本 實施例，掛勾開關電路300的掛下勾信號爲一高電壓，此 高電壓會將激磁線圈激磁，並且接上繼電器上的開關，使 開關會進一步地將電話線連接起來，所以，當掛下勾信號 送至掛勾開關電路300時，此掛勾開關電路300會將電話 線連接起來；而掛上勾信號爲一低電壓1此低電壓並不會 將激磁線圏激磁，所以不會接通繼電器上的開關，使開關 不會接至電話線，所以，當掛上勾信號送至掛勾開關電路 300時，此掛勾開關電路300會將電話線切斷。過載偵測 7 -------------种衣------，玎------.ii (請先閱讀背面之注意事項再填寫本頁) 本紙浪尺度適用中國國家標準（CNS ) A4规格（210X297公釐） 416206 4538twf.doc/006 A7 B7 經濟部中央標準局貝工消费合作社印聚 五、發明説明（6 ) 電路100是由電阻器R2，耦接於橋式整流器之正電壓輸出 端以及al節點，電阻器R3，耦接於al節點以及橋式整流 器之負電壓輸出端’電容器C1，耦接於al節點以及橋式 整流器負電壓輸出端，光耦合器U1，之第三腳位耦接至 接地點，第四腳位耦接至強制掛上勾電路200,電阻器R1， 耦接於橋式整流器正電壓輸出端以及光耦合器U1之第一 腳位，電晶體Q1之集極耦接至光耦合器U1之第二腳位， 射極耦接至橋式整流器負電壓輸出端，基極耦接至al節 點。而電晶體Q1的基極電壓是由電阻器R2、R3分壓電路 所提供，當電晶體Q1的基極電壓達到（L65V時，電晶體 Q1導通，使得光耦合器內的二極體導通，更進一步地耦 合至光耦合器內的電晶體，並且導通光耦合器內的電晶 體，使得光耦合器的3、4腳位導通，因爲光耦合器第3 腳位爲接地，故此接地低電壓信號就是過載信號。強制掛 上勾電路200是由電阻器R5，耦接至電壓源Vcc以及a2 節點，並且節點耦接至過載偵測電路100，反閘U4F之 輸入端耦接至a2節點，或閘U2B的一輸入端耦接至反閘 U4F之輸出端，或閘U2B之輸出端耦接至a3節點，及閘 U3A的一輸入端耦接至a3節點，及閘U3A的另一輸入端 耦接至傳真/數據機控制器400，並且及閛U3A之輸出端耦 接至或閘U2B的另一輸入端，電阻器R4，親接至該a3節 點以及a4節點，電容器C2，耦接至a4節點以及接地點， 電晶體Q2其閘極耦接至a4節點，源極耦接至接地點，汲 極耦接至掛勾開關電路300以及傳真/數據機控制器400。 8 本紙張尺度適用中國國家^率（CNS ) A4規格（210X297公釐) " "" -----------參------tx------線> (請先聞讀背面之注意事項再填寫本頁〕 經濟部中央橾準局貝工消費合作社印製 416206 4538twf . doc/006 A 7 _B7_ 五、發明说明（Q) 而電阻器R5爲上推電阻（pull-up resistance)，當低電壓 的過載信號成爲反閘U4F的輸入，反閘U4F的輸出爲高電 壓，再將此高電壓當作或閘U2B的輸入，則或閘U2B的 輸出就爲高電壓，此高電壓經過電阻器R4及電容器C2組 成的RC充電電路，開始向電容器C2充電，經過時 2πΚΑ02 間後，電容器C2.上的電壓已能夠將電晶體Q2導通，此時 掛勾開關電路300上的輸入訊號.變爲低電壓，而作掛上勾 的動作 '將電話線切斷。 請參照第4圖，其所繪示爲本發明應用於傳真/數據 機電話線上之高溫保護裝置電路圖。偵測電路700是由熱 敏電阻THR1所組成’可置於傳真/數據機電路中較容易產 生溫度異常的元件旁，依照本實施例此偵測電路700,是 置於電流限制電路900上的電晶體組910旁，用以偵測電 流限制電路900上的溫度狀況，強制掛上勾電路200是由 電阻器R6 ’耦接至a5節點以及接地點，並且a5節點耦接 至高溫偵測電路，電容器C3，耦接至a5節點以及接地點， 電晶體Q3之閘極耦接至該a5節點’源極耦接至接地點’ 汲極耦接至掛勾開關電路300以及傳真/數據機控制器 400。電晶體Q3的閘極電壓是由熱敏電阻THR1和電阻器 R6所形成之分壓電路所提供，當電路元件產生高溫時， 熱敏電阻THR1的電阻値下降，電晶體Q3的閘極電壓上 升，當溫度上升到達一極限時，當電晶體Q3的閘極電壓 會上升至一定値時，此電壓即爲高溫信號，此高電壓將電 9 ----------丨^.------,訂------線 (請先閱讀背面之注意事項再填寫本頁) 本紙張尺度適用中國囷家棣準（CNS ) A4規格（210X297公釐）4-6206 4538twf, d00 / 006 B7 printed by the Shellfish Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs 5. Description of the Invention (丨) The present invention relates to a circuit protection device, and more particularly to a circuit protection device applied to a telephone line. protective device. Due to the rapid development of technology, interaction between people is more frequent. Telephones, fax machines, modems, and other electrical appliances used on telephone lines have gradually become indispensable tools in our daily lives. When an Integrated Services Digital Network (ISDN) plug is inserted, or a Private Brandi Exchange (PBX) fails, or the telephone line of a telecommunications office fails, an abnormally high voltage on the telephone line and Large currents can cause damage to electrical appliances on the telephone line. Please refer to FIG. 1, which depicts a protection device for a conventional telephone line. The telephone line is connected through the socket 40, and the action of the telephone line connection is based on the fax / modem controller 12 sending a signal to the hook switch. Circuit 14 is connected to the telephone line, and the protection device is a fuse or poly switch 10 in series on the telephone line of the fax / data machine to prevent the overvoltage or overcurrent of the telephone line from passing through. Causes damage to the fax / modem on the phone line, and the disadvantage of this protection device is that the high current will burn the fuse or polycrystalline silicon switch. You must reinstall a new fuse or polycrystalline silicon switch to restore the fax / modem to normal operation. It is very inconvenient to use; and in the European standard that more restricts the fax / data modem circuit, there must be a Current Limit circuit_ 20 '. However, if there is a current limit circuit 20 in the circuit, the current will be affected by this when an overcurrent is generated. The current limiting circuit 20 is limited to a fixed voltage, however, this fixed current may cause the transistor group 30 to burn out due to excessive temperature or voltage, or If the cabinet temperature is too high and burned, the current and circuit cannot be truly achieved. 3: Paper (CNS) 21 () > < 297 Gong) II —: — 11 —— Order I 1 line (Please read the precautions on the back before filling out this page.) Consumer cooperation of the Bureau of Loss and Standards of the Ministry of Economic Affairs Du printed 416206 4538twf.doc / 006 A7 ___B7_ 5. Description of the invention (\) The function of pressure protection. Therefore, the present invention proposes a protection device applied to a telephone line. 'Data Access ArnuigemeiU' DAA line adds a protection device to a telephone line when abnormal overvoltage or overcurrent signals appear on the telephone line. , The overload detection circuit will detect this overvoltage or current and send an overload signal to the forced on hook circuit; or when an abnormal temperature rise occurs on the telephone line, the high temperature detection circuit will Detect this temperature change, and send the tube temperature signal to the hook circuit. When the hook circuit receives an overload signal or a high temperature signal, it will hook the hook switch (HOK Swiich). When the telephone line is hooked, the fax / modem driver will find that there is no carrier on the telephone line, which will force the DAA line to be hooked. Therefore, the parts can be prevented from being burned due to high voltage or high temperature, and the purpose of protecting the circuit is achieved. . The invention proposes a protection device applied to a telephone line, which can quickly detect abnormal conditions on the telephone line, and hook the telephone line to achieve the purpose of protecting the circuit. The present invention provides a protection device applied to a telephone line, which is briefly described as follows: An overvoltage and overcurrent protection device applied to a telephone line, which is connected to the telephone line, includes: a bridge rectifier using a telephone line as the bridge type The input end of the rectifier is connected in parallel with the telephone line, and the telephone line voltage is used as the input of the bridge rectifier. The telephone line voltage is rectified to the rectified voltage and sent to the bridge. Α4 Specification (2Ι ×× 297 mm) I 1 ^ -------- ΪΤ ------ Μ (Please read the notes on the back before filling out this page} Printed by the Consumers 'Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs 416206' 4538twf.doc / 006 A7 B7 V. Description of the invention (3 >) output terminal of the rectifier. An overload detection circuit is coupled to the output terminal of the bridge rectifier to receive the rectified voltage, and when the rectified voltage exceeds the preset 値When the overload signal is sent, the hook circuit is forced to be coupled to the overload detection circuit, and the hook signal is generated according to the overload signal and the hook signal. The hook switch circuit is coupled to the force. The hook circuit is connected to the telephone line in series, and is used to make the hook line of the telephone line according to the received hook signal. A protection device applied to the fax / data machine to protect the fax / data machine circuit from In case of overheating, the protection device includes: a detection circuit for detecting the temperature of the facsimile / modem circuit. When the temperature exceeds a preset threshold, an overload signal is sent out. The hook circuit is forced to be coupled to the detection circuit, and The hook signal is generated according to the overload signal and the hook signal. The hook switch circuit is coupled to the forced hook circuit and is connected in series to the telephone line to hang the telephone line according to the received hook signal. In order to make the above-mentioned objects, features, and advantages of the present invention clearer and easier to understand, the preferred embodiments are described below in detail with the accompanying drawings as follows: Brief description of the drawings: Section 1 Figure 2 depicts a conventional telephone line protection and current limiting circuit; Figure 2 illustrates a block diagram of an overvoltage and overcurrent protection device applied to a telephone line according to the present invention; Figure 3 illustrates its location Shown are circuit diagrams of overvoltage and overcurrent protection devices applied to telephone lines according to the present invention; and 5 paper sizes using China National Standards (CNS) A4 specifications (210X297 mm) n nn n ^ (Please read the note on the back first Please fill in this page again] 4538twf.doc / 006 A7 B7 Printed by the Consumers' Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs ^ V. Description of the Invention (if) Figure 4 shows the circuit diagram of the high temperature protection device applied to the telephone line of the present invention. Explanation of symbols: 10 fuse or polycrystalline silicon switch 12 fax / modem controller 14 hook switch circuit 20 current limit circuit 30 transistor group 40 socket 50 bridge rectifier 60 socket 100 overload detection circuit 200 forced hook circuit 300 hook Switch circuit 400, fax / modem controller 700, detection circuit (thermistor), 900 current limit circuit, 910 transistor group. Please refer to FIG. 2 for an embodiment of the present invention. Block diagram of overvoltage and overcurrent protection devices. The telephone line is connected through the socket 60. Nodes a and b of the bridge rectifier 50 are connected to the telephone line. The telephone line voltage ν on the telephone line is rectified by the bridge rectifier 50 to form a rectified voltage V2. Bridge paper rectifier 50c, 6 This paper size is applicable to Chinese national standard (CNS ^ A4 specification (210X 297mm Γ " ------------ ^ ------ 1T-- ----. ^ (Please read the notes on the back before filling out this page) Consumer Cooperation of the Central Bureau of Standards of the Ministry of Economic Affairs 416206 4538twf.d〇c / 006 ._ A7 B7 V. Description of the Invention ($) d The node is the input terminal and is sent to the overload detection circuit 100. Nodes a and b of the bridge rectifier 50 are used as the input terminal. However, when the telephone line connector is incorrectly inserted into the integrated service digital network plug, or the switch fails, or the telecommunications office When the telephone line is faulty, there will be abnormal high voltage and large current on the telephone line. When the abnormally high telephone line voltage occurs on the telephone line, the bridge rectifier 50 and the overload detection circuit 100 judge the telephone based on the rectified voltage. There is abnormally high telephone line voltage on the line. At this time, the overload detection The test circuit 100 will send an overload signal to the forced hook circuit _ 200. When the forced hook circuit 200 receives the overload signal, it will change the hook signal from the fax / modem controller 400 to the hook signal. According to this embodiment, the hook switch circuit 300 is composed of a relay (Relay). When the hook-down signal is sent to the hook switch circuit 300, the hook switch circuit 300 will connect the telephone line, When the hook signal is sent to the hook switch circuit 300, the hook switch circuit 300 will cut off the telephone line. Please refer to FIG. 3, which shows the overvoltage and overvoltage applied to the fax / data phone line of the present invention. Circuit diagram of the current protection device. According to this embodiment, the hook signal of the hook switch circuit 300 is a high voltage. This high voltage will excite the exciting coil and connect the switch on the relay, so that the switch will further connect the telephone line. It is connected, so when the hook signal is sent to the hook switch circuit 300, the hook switch circuit 300 will connect the telephone line; and the hook signal is a low voltage 1 this low voltage and The excitation line will be excited, so the switch on the relay will not be turned on, so that the switch will not be connected to the telephone line. Therefore, when the hook signal is sent to the hook switch circuit 300, the hook switch circuit 300 will Telephone line is cut off. Overload detection 7 ------------- Seed coat ------, 玎 ------. Ii (Please read the precautions on the back before filling (This page) This paper applies the Chinese National Standard (CNS) A4 specification (210X297 mm) 416206 4538twf.doc / 006 A7 B7 Printed by the Central Standards Bureau of the Ministry of Economic Affairs, Shellfish Consumer Cooperatives. 5. Description of the invention (6) Circuit 100 is made by The resistor R2 is coupled to the positive voltage output terminal and the al node of the bridge rectifier, and the resistor R3 is coupled to the al node and the negative voltage output terminal 'capacitor C1 of the bridge rectifier, and is coupled to the al node and the bridge rectifier. The negative voltage output terminal, the third pin of the photocoupler U1, is coupled to the ground point, the fourth pin is coupled to the forced hook circuit 200, and the resistor R1 is coupled to the positive voltage output terminal of the bridge rectifier and The first pin of the photocoupler U1, the collector of the transistor Q1 is coupled to the second pin of the photocoupler U1 , An emitter coupled to the bridge rectifier negative output terminal, a base coupled to node al. The base voltage of transistor Q1 is provided by the resistor R2 and R3 voltage-dividing circuits. When the base voltage of transistor Q1 reaches (L65V, transistor Q1 is turned on, making the diode in the optocoupler conductive. Is further coupled to the transistor in the optocoupler, and the transistor in the optocoupler is turned on, so that pins 3 and 4 of the optocoupler are turned on. Because pin 3 of the optocoupler is grounded, the ground is low. The voltage signal is an overload signal. The forced hook circuit 200 is connected to the voltage source Vcc and the a2 node by a resistor R5, and the node is coupled to the overload detection circuit 100. The input terminal of the reverse brake U4F is coupled to the a2 node. An input terminal of OR gate U2B is coupled to the output terminal of reverse gate U4F, or an output terminal of gate U2B is coupled to node a3, and an input terminal of gate U3A is coupled to node a3, and the other input of gate U3A The terminal is coupled to the fax / modem controller 400, and the output terminal of the U3A is coupled to the other input terminal of the OR gate U2B, the resistor R4, is connected to the a3 node and the a4 node, and the capacitor C2 is coupled. To node a4 and ground, transistor Q2 has its gate coupled to a4 Point, the source is coupled to the ground point, and the drain is coupled to the hook switch circuit 300 and the fax / modem controller 400. 8 This paper size applies to the Chinese National Standard (CNS) A4 specification (210X297 mm) " " " ----------- See ------ tx ------ line > (Please read the notes on the back before filling this page) Central Ministry of Economic Affairs 橾416206 4538twf.doc / 006 A 7 _B7_ printed by the Zhuhai Bureau Shellfish Cooperative Co., Ltd. 5. Description of the invention (Q) and the resistor R5 is a pull-up resistance. When the low-voltage overload signal becomes the reverse brake U4F Input, the output of reverse gate U4F is a high voltage, and then this high voltage is used as the input of OR gate U2B, then the output of OR gate U2B is a high voltage. This high voltage passes through the RC charging circuit composed of resistor R4 and capacitor C2. Start to charge capacitor C2. After 2πκΑ02, the voltage on capacitor C2. Can turn on transistor Q2. At this time, the input signal on hook switch circuit 300 becomes low voltage, and the hook is Action 'Disconnect the telephone line. Please refer to Figure 4, which shows the application of the present invention to the fax / data electromechanical Circuit diagram of the high-temperature protection device on the telephone line. The detection circuit 700 is composed of a thermistor THR1. It can be placed next to a component that is prone to temperature abnormalities in the fax / data machine circuit. According to this embodiment, the detection circuit 700 is It is placed next to the transistor group 910 on the current limiting circuit 900 to detect the temperature condition on the current limiting circuit 900. The forced hook circuit 200 is coupled to the a5 node and the ground point by a resistor R6 ', and a5 The node is coupled to the high temperature detection circuit, the capacitor C3 is coupled to the a5 node and the ground point, and the gate of the transistor Q3 is coupled to the a5 node. The source is coupled to the ground point. The drain is coupled to the hook switch. Circuit 300 and facsimile / modem controller 400. The gate voltage of transistor Q3 is provided by a voltage dividing circuit formed by thermistor THR1 and resistor R6. When the circuit element generates high temperature, the resistance of the thermistor THR1 decreases, and the gate voltage of the transistor Q3 Rise, when the temperature rise reaches a limit, when the gate voltage of transistor Q3 will rise to a certain value, this voltage is a high temperature signal, and this high voltage will be 9 ---------- 丨 ^ .------, order ------ line (Please read the precautions on the back before filling this page) This paper size is applicable to China National Standard (CNS) A4 (210X297 mm)