CN204929141U - Campus broadcast intercom and monitoring system - Google Patents

Abstract

The campus broadcast intercom and monitoring system is a multi-functional system designed for schools and enterprises that can not only monitor, but also two-way conversation, and can also realize single-point, partition or comprehensive broadcasting. It mainly includes condenser microphones, preamplifier circuits, Relays, broadcast signal bypass capacitors, broadcast audio transformers, single-pole three-throw selector switches, double-pole double-throw function switches and constant voltage power amplifiers; preamplifier circuits in classroom speakers, relays and broadcast signal bypass capacitors are connected in parallel In series with the broadcast audio transformer, they form an AC signal and DC current detection circuit, which can automatically adapt to the AC signal and DC current on the transmission line, so that the preamplifier circuit and the broadcast audio transformer work in turn to complete the system broadcast and monitoring process.

Description

Campus broadcast intercom and monitoring system

technical field

The invention relates to the technical field of cable broadcasting, in particular to a classroom broadcasting system with room-by-room broadcasting and monitoring functions, which is a teaching and management auxiliary device for room-by-room broadcasting, two-way intercom and sound monitoring used in schools or enterprises.

Background technique

In school teaching management, it often involves teaching quality inspection or classroom teaching inspection, such as whether each class attends classes on time, whether classroom teaching time is effectively used, and whether teachers' teaching language is standardized and scientific. There are three commonly used methods: the first is to attend lectures on site; the second method is to use wireless microphones for monitoring; the third method is to use wired microphones for sound transmission. Among them, the first method can only listen to one class regularly, and cannot keep abreast of the classroom teaching situation of all classes in the school; the second method is troublesome to operate, requiring frequent movement of the microphone and receiver, frequent replacement of batteries, and constant adjustment of the frequency of the receiver , and the timbre is poor, and the noise is large. In the third method, the speaker should not be far away from the microphone, otherwise the voice will be small and the noise will be loud. At present, there is also a bus-type addressing broadcast system, which can perform regional broadcasting and fixed-point broadcasting, but does not have fixed-point intercom and monitoring functions.

Utility model content

The purpose of the present invention is to provide a broadcast intercom and monitoring system used in schools or enterprises, which can solve the technical problems of room-by-room broadcasting, two-way intercom and indoor sound monitoring.

The technical problem to be solved by the present invention is achieved through the following technical solutions: the system includes a condenser microphone, a preamplifier circuit, a relay, a broadcast signal bypass capacitor, a broadcast audio transformer, a single-pole three-throw selector switch, a double-pole double-throw function switch and Constant voltage power amplifier part; pre-amplifier circuit, relay, broadcast signal bypass capacitor and broadcast audio transformer are set in the classroom speaker, and the pre-amplifier circuit, relay and broadcast signal bypass capacitor are connected in parallel and then connected in series with the broadcast audio transformer. Form the AC signal and DC current detection circuit, automatically adapt to the AC signal and DC current on the transmission line, so that the preamplifier circuit and the broadcast audio transformer work in turn; when the system uses the broadcast function, the transmission line is an AC signal, and the broadcast signal bypass capacitor The operating voltage of the preamplifier circuit and relay is bypassed, the preamplifier circuit and relay stop working, the monitoring function stops, the normally open contact of the relay is disconnected, all broadcast signals are loaded on the broadcast audio transformer, the broadcast works normally, and the classroom speakers The speaker can make sound; when the system uses the monitoring function, the main signal on the transmission line is a DC current, and the broadcast signal bypass capacitor does not act as a short circuit to the working voltage of the preamplifier circuit and the relay, the preamplifier circuit works, and the relay pulls in, The normally open contact of the relay is connected, and the speakers in the classroom will not sound. The monitoring signal is superimposed on the transmission line through the normally open contact of the relay, and then sent to the input jack of the constant voltage power amplifier. After being amplified by the constant voltage power amplifier, the monitor speaker will sound , to complete the monitoring process.

The above-mentioned technical solution has the following beneficial effects: providing simple electronic circuits for schools and enterprises, realizing a multi-functional system capable of monitoring, two-way conversation, and single-point or partition or full-scale broadcasting.

Description of drawings

The present invention has following 2 drawings:

Figure 1 is the preamplifier circuit of the system and the internal circuit structure diagram of the classroom speakers;

Fig. 2 is the circuit diagram of this system.

The numbers marked in the accompanying drawings represent respectively as follows:

1. Condenser microphone; 2. Input coupling capacitor; 3. Polarization resistor; 4. Bias resistor; 5. Transistor 1; 6. Transistor 2; 7. Collector resistor; 8. Decoupling resistor; 9. Output Coupling capacitor; 10, directional diode; 11, monitor signal output terminal; 12, decoupling capacitor; 13, emitter resistor one; 14, emitter bypass capacitor; 15, emitter resistor two; 16, filter capacitor; 17, Preamplifier circuit; 18. Relay; 19. Speaker positive terminal; 20. Broadcast audio transformer; 21. Classroom speaker speaker; 22. Relay normally open contact; 23. Broadcast signal bypass capacitor; 24. Speaker negative terminal ;25, classroom speaker part; 26, transmission line; 27, single-pole three-throw selection switch; 28, the same line ellipsis; 29, light-emitting diode; 30, monitoring signal bypass capacitor; 31, current-limiting resistor; 32, choke Coil; 33, upper contact of double pole double throw switch; 34, double pole double throw function switch; 35, lower contact of double pole double throw switch; 36, DC power lead-out end; 37, broadcast signal output end; 38, monitor Speaker; 39, audio transformer; 40, volume knob; 41, system host; 42, constant voltage power amplifier; 43, power amplifier input jack; 44, transmission line output end; 45, transmission line common ground.

Detailed ways

1. According to Figure 2, the system mainly includes a condenser microphone (1), a preamplifier circuit (17), a relay (18), a broadcast signal bypass capacitor (23), a broadcast audio transformer (20), and a single-pole three-throw selection switch ( 27), double-pole double-throw function switch (34) and constant pressure power amplifier (42) part; Preamplifier circuit (17), relay (18) and broadcast signal bypass capacitor (23) are connected in parallel and then connected with broadcast audio The transformer (20) is connected in series, and the operating voltage of the relay (18) is also the operating voltage of the preamplifier circuit (17). When the system uses the monitoring function, the main signal on the transmission line is a direct current, and the preamplifier circuit (17) and The working voltage of the relay (18) is provided by the primary coil of the broadcast audio transformer (20) after stepping down.

2. When one or more or all single-pole three-throw selector switches (27) are dialed on the upper contact, and the double-pole double-throw function switch (34) is also dialed on the upper contact, the broadcast of the constant-voltage power amplifier (42) The output signal is sent to one or more or all classroom speaker parts (25), because the broadcast signal is an AC signal, the broadcast signal bypass capacitor (23) is unimpeded to the broadcast signal, and the broadcast signal bypass capacitor (23) connects the relay ( 18) and the operating voltage of the preamplifier circuit (17) are short-circuited, the relay (18) does not work, the normally open contact (22) is open, the broadcast signal is all loaded on the broadcast audio transformer (22), and the broadcast works normally. At the same time, through the operation of the number of single-pole three-throw selection switches (27), the system can realize single-point or partition or comprehensive broadcasting functions.

3. When one single-pole three-throw selector switch (27) is dialed at the lower contact, the rest of the SP3-Throw selector switches (27) are all dialed at the middle contact, and the double-pole double-throw switch (34) is also dialed at the lower contact , the direct current of the direct current power outlet (36) is sent to the relay ( 18) and preamplifier circuit (17), provide power supply for preamplifier circuit (17) and relay (18), and light-emitting diode (29) is lighted now, shows that monitoring circuit is connected; Because transmission line (26) It is direct current, and the broadcast signal bypass capacitor (23) is not smooth to direct current, so the broadcast signal bypass capacitor (23) does not act as a short circuit to the working voltage of the relay (18) and the preamplifier circuit (26), and the relay (18) and the preamplifier circuit (26) work normally, the relay pulls in (18), and the normally open contact (22) path; the condenser microphone (1) receives the sound in the classroom, and the monitoring signal amplified by the preamplifier circuit (17) Loaded on the transmission line (26) through the relay normally open contact (22), superimposed with the DC voltage on the transmission line (26), the monitoring signal is coupled to the power amplifier input jack (43) through the monitoring signal bypass capacitor (30) After the monitoring signal is amplified by the constant voltage power amplifier (42), the signal is loaded onto the audio transformer (39) through the broadcast signal output terminal (37) and the double-pole double-throw switch (34), and the monitoring speaker (38) is used after the voltage transformation. Work to realize the monitoring function.

4. Using the single-point broadcasting function and the monitoring function, the intercom function between the classroom and the control room can be realized by simultaneously changing the single-pole three-throw selection switch (27) and the double-pole double-throw function switch (34).

5. When the system is in the broadcast state, the monitor speaker (38) can be used as a microphone. The monitor speaker (38) receives the voice signal of the announcer and converts it into an electrical signal. After the audio transformer (39) boosts the voltage, the broadcast signal passes through The contact piece on the left side of the upper contact point (33) of the double pole double throw switch is sent to the power amplifier input jack (43), and after being amplified by the constant voltage power amplifier (42), it passes through the right contact piece of the upper contact point (33) of the double pole double throw switch It is sent to the transmission line, and then sent to the speakers in each classroom for sound.

6. Due to the large number of classrooms in actual schools or studios in enterprises, it is the same as the transmission line (26), single-pole three-throw selection switch (27), light-emitting diode (29) and monitoring signal bypass capacitor (30) in Fig. 2 The circuit part is not all drawn, and is replaced with the same circuit ellipsis (28).

7. According to Fig. 1, the function of the directional diode (10) is to ensure that the polarity of the power supply of the preamplifier circuit (17) is up positive and down negative, when the speaker positive terminal (19) and the speaker negative terminal (24) are connected to the transmission When the line is reversed, the preamplifier circuit (17) can also work normally.

8. According to Figure 1, the capacitors in the figure are all electrolytic capacitors, the input coupling capacitor (2) is 2.2μF/25V; the output coupling capacitor (9) is two 22μF/25V; the decoupling capacitor (12) is 100μF /25V; the emitter bypass capacitor (14) is 220μF/10V; the filter capacitor (16) is 220μF/25V; the broadcast signal bypass capacitor (23) adopts two 22μF/250V; the resistors all adopt 1/8W carbon film Resistor, polarization resistor (3) is 47K; bias resistor (4) is 2.2M; collector resistor (7) is 10K; decoupling resistor (8) is 1K; emitter resistor one (13) is 5.1K ; Emitter resistor two (15) 2.2K; Transistor one (5) and transistor two (6) use plastic encapsulated transistors, the model is 9013; the model of 4 directional diodes (10) is 1N4007; Relay (18) selects JRX-13F for use type DC 12V relay, the DC resistance of the coil is 600Ω; the operating voltage of the relay normally open contact (22) is AC 220V, and the contact operating current is greater than AC 1A; the primary operating voltage of the broadcast audio transformer (20) is 120V, and the DC resistance is 600Ω , the secondary output impedance is 8Ω; the classroom speaker speaker (21) has an impedance of 8Ω, a power of 5W, and a caliber of 120mm.

9. According to Fig. 2, the single-pole three-throw selection switch (27) is a miniature three-speed toggle switch; the light-emitting diode (29) is a φ3 green light-emitting diode; the monitoring signal bypass capacitor (30) is a 22μF/25V electrolytic capacitor; current limiting The resistance (31) is a 2W100Ω metal film resistance; the choke coil (32) is 0.2H; the double-pole double-throw function switch (34) is a toggle switch; the voltage of the DC power supply terminal (36) is 24V; the broadcast signal output terminal The voltage of (37) is 0-120V; Monitor loudspeaker (38) is 0.5W8Ω; Audio transformer (39) primary working voltage is 120V; Constant voltage power amplifier (42) is 100W, and constant voltage value is 120V.

10. According to Figure 2, the transmission line (26) adopts Category 5 twisted pair wires, and 7 of the 8 cores are respectively laid to 7 classrooms, connected to the positive pole terminal (19) of the classroom speaker, and the last one is used as a public Ground wire uses, is connected on the sound box negative electrode terminal (24), and the other end of twisted pair is connected on the transmission line output (44) of system host computer (41) and on the transmission line public ground (45) respectively.

11. The wiring method of other classrooms is the same as that of Embodiment 10.

Claims (3)

1. campus broadcasting intercommunication and a monitoring system, comprises capacitor microphone, pre-amplification circuit, relay, broadcast singal shunt capacitance, broadcast audio transformer, SP3T selector switch, dpdt double-pole double-throw (DPDT) functional switch and level pressure power amplifier part; Pre-amplification circuit, relay, broadcast singal by-pass capacitor and broadcast audio transformer are set in the audio amplifier of classroom, their composition AC signal and D.C. current detecting circuits, AC signal on automatic adaptation transmission line and direct current, pre-amplification circuit and broadcast audio transformer are taken turns to operate, it is characterized in that: after pre-amplification circuit, relay and broadcast singal by-pass capacitor three parallel connection again with broadcast audio transformer series.

2. campus broadcasting intercommunication according to claim 1 and monitoring system, it is characterized in that: during system use broadcast capability, broadcast singal by-pass capacitor bypasses the operating voltage of pre-amplification circuit and relay, pre-amplification circuit and relay quit work, monitor function stops, relay normally open contact is opened a way, and broadcast audio transformer normally works, and classroom speaker is sound.

3. campus broadcasting intercommunication according to claim 1 and monitoring system, it is characterized in that: during system use monitor function, main signal on transmission line is direct current, broadcast singal by-pass capacitor can not short circuit to the operating voltage of pre-amplification circuit and relay, pre-amplification circuit works, relay adhesive, relay normally open contact path, monitor function is normal, and classroom speaker is noiseless.