CN202679547U - Signal input frequency selector for frequency modulation interphone - Google Patents
Signal input frequency selector for frequency modulation interphone Download PDFInfo
- Publication number
- CN202679547U CN202679547U CN2012203163651U CN201220316365U CN202679547U CN 202679547 U CN202679547 U CN 202679547U CN 2012203163651 U CN2012203163651 U CN 2012203163651U CN 201220316365 U CN201220316365 U CN 201220316365U CN 202679547 U CN202679547 U CN 202679547U
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- frequency
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- triode
- diode
- electric capacity
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Abstract
The utility model discloses a signal input frequency selector for a frequency modulation interphone, comprising a filter circuit and a frequency selecting circuit, wherein the filter circuit is connected with a signal input end; the line between the filter circuit and the frequency selecting circuit is connected with a voltage amplitude limiting circuit which comprises a first diode and a second diode; the negative electrode of the first diode and the positive electrode of the second diode are connected with the line between the filter circuit and the frequency selecting circuit; the frequency selecting circuit comprises a first resistor, a first triode, a third capacitance and a variable capacitance; the connection end for the filter circuit and the frequency selecting circuit is connected with the line between the first resistor and the base of the first triode; the third capacitance and the variable capacitance are in parallel so as to form a parallel line; and one end of the parallel line is connected with the collector of the first triode, and the other end of the parallel line is connected with a signal output end. Using the above structure, the signal input frequency selector for a frequency modulation interphone can avoid the situation that the field effect tube in the interphone is damaged because of overlarge voltage during the operation process of the signal input frequency selector for a frequency modulation interphone, thus being convenient to popularize and apply the interphone.
Description
Technical field
The utility model relates to communication equipment field, specifically is used for the signal input frequency-selector of frequency-modulation intercom for use.
Background technology
In modern communications, intercom be a kind of closely, simple wireless transmission means of communication because it does not need terminal and switch station, ground to support just can carry out effective mobile communication, so be loved by the people.Intercom can be divided into amplitude modulation and frequency modulation type on modulation system, wherein, frequency-modulation intercom for use is to make the receive frequency of one group of intercom identical with the tranmitting frequency of another group intercom with tranmitting frequency by regulating frequency and receive frequency, thereby realizes the wireless communication facility of intercommunication function.Frequency-modulation intercom for use is widely used in the industries such as public security, civil aviaton, transportation, water conservancy, railway, manufacturing, building, service, and especially in the place that network can't cover, frequency-modulation intercom for use becomes the means of communication that people like.Yet during existing frequency-modulation intercom for use work, if the overtension that produces on its antenna, the grid of field effect transistor is easily breakdown and damage in the intercom, and process is loaded down with trivial details when the element in the intercom changed, and this has just affected applying of intercom.
The utility model content
The purpose of this utility model is to overcome the deficiencies in the prior art, provide a kind of simple in structure, be convenient to realize, and can with the antenna reception of intercom to voltage carry out amplitude limit, thereby can avoid the signal input frequency-selector that is used for frequency-modulation intercom for use that field effect transistor is damaged because of overtension in the intercom.
The purpose of this utility model is achieved through the following technical solutions: the signal input frequency-selector that is used for frequency-modulation intercom for use, comprise filter circuit and the frequency selection circuit that is connected with filter circuit, described filter circuit is connected with signal input part, be connected with voltage limiter circuit on the circuit between filter circuit and the frequency selection circuit, described voltage limiter circuit comprises the first diode and the second diode, described the first diode cathode and the second diode cathode all are connected on the circuit between filter circuit and the frequency selection circuit, the first diode cathode and the equal ground connection of the second diode cathode; Described frequency selection circuit comprises the first resistance, the first triode, the 3rd electric capacity and variable capacitance, described the first resistance one end is connected with the base stage of the first triode, the first resistance connects the other end ground connection of the first transistor base end relatively, the link of filter circuit and frequency selection circuit is connected on the circuit between the first resistance and the first transistor base, the grounded emitter of the first triode, described the 3rd electric capacity and variable capacitance formation in parallel parallel line, this parallel line one end is connected with the collector electrode of the first triode, and its other end is connected with signal output part.
Described filter circuit comprises the first electric capacity, the second electric capacity and the first inductance, described the first inductance two ends respectively with the first electric capacity be connected electric capacity and be connected, the first electric capacity be connected electric capacity and relatively connect the other end ground connection of the first inductance end, described signal input part is connected on the circuit between the first electric capacity and the first inductance, and the link of described frequency selection circuit and filter circuit is connected on the circuit between the first inductance and the second electric capacity.
Described the first triode is the NPN triode.
Compared with prior art, the utlity model has following beneficial effect: (1) the utility model comprises filter circuit, frequency selection circuit and voltage limiter circuit, wherein, voltage limiter circuit comprises the first diode and the second diode, the utility model realizes that the components and parts of voltage limiter circuit are few, simple in structure, be convenient to realize, cost is low, utilize the lower characteristic of diode forward pressure drop during the utility model work, can be with voltage amplitude limit in the input intercom below 0.7V, thus can avoid in the intercom field effect transistor to damage because of high pressure, and this just more is conducive to applying of intercom.
(2) frequency selection circuit of the present utility model is provided with the first triode and variable capacitance, and the utility model can be by being added in voltage swing on the first triode, and then come frequency selection circuit is turn-offed and conducting control, further the utility model protected; The utility model can be regulated and control the frequency of selecting by variable capacitance, and then increases range of application of the present utility model.
Description of drawings
Fig. 1 is the structural representation of the utility model embodiment.
The corresponding name of Reference numeral is called in the accompanying drawing: C1-first electric capacity, C2-second electric capacity, C3-the 3rd electric capacity, VC1-variable capacitance, R1-first resistance, L1-first inductance, D1-first diode, D2-second diode, Q1-first triode, 1-signal input part, 2-signal output part.
Embodiment
The utility model is described in further detail below in conjunction with embodiment and accompanying drawing, but execution mode of the present utility model is not limited to this.
Embodiment:
As shown in Figure 1, the signal input frequency-selector that is used for frequency-modulation intercom for use, comprise filter circuit and the frequency selection circuit that is connected with filter circuit, wherein, filter circuit comprises the first capacitor C 1, the second capacitor C 2 and the first inductance L 1, the first inductance L 1 two ends respectively with the first capacitor C 1 be connected capacitor C 2 and be connected, the first capacitor C 1 be connected capacitor C 2 both relatively connect other end ground connection of the first inductance L 1 ends, be connected with signal input part 1 on the circuit between the first capacitor C 1 and the first inductance L 1, the link of frequency selection circuit and filter circuit is connected on the circuit between the first inductance L 1 and the second capacitor C 2.Be connected with voltage limiter circuit on the circuit between filter circuit and the frequency selection circuit, voltage limiter circuit comprises the first diode D1 and the second diode D2, the first diode D1 negative pole and the second diode D2 positive pole all are connected on the circuit between filter circuit and the frequency selection circuit, the anodal and equal ground connection of the second diode D2 negative pole of the first diode D1.
Frequency selection circuit comprises the first resistance R 1, the first triode Q1, the 3rd capacitor C 3 and variable capacitance VC1, the first triode Q1 preferably adopts the NPN triode, the first resistance R 1 one ends are connected with the base stage of the first triode Q1, and the first resistance R 1 connects the other end ground connection of the first triode Q1 base terminal relatively.The link of filter circuit and frequency selection circuit is connected on the circuit between the first resistance R 1 and the first triode Q1 base stage, the grounded emitter of the first triode Q1.The 3rd capacitor C 3 and variable capacitance VC1 formation in parallel parallel line, this parallel line one end is connected with the collector electrode of the first triode Q1, and its other end is connected with signal output part 2.
When being used for the signal input frequency-selector work of frequency-modulation intercom for use, the voltage that interphone antenna receives is inputted frequency selection circuit after the wave circuit filtering after filtration, if the overtension of filter circuit output, the first diode D1 and the second diode D2 of voltage limiter circuit carry out amplitude limit to voltage, carry out frequency-selecting in the input frequency selection circuit after voltage is processed through voltage limiter circuit and process.
As mentioned above, then can well realize the utility model.
Claims (3)
1. the signal input frequency-selector that is used for frequency-modulation intercom for use, it is characterized in that: comprise filter circuit and the frequency selection circuit that is connected with filter circuit, described filter circuit is connected with signal input part (1), be connected with voltage limiter circuit on the circuit between filter circuit and the frequency selection circuit, described voltage limiter circuit comprises the first diode (D1) and the second diode (D2), on the anodal circuit that all is connected between filter circuit and the frequency selection circuit of described the first diode (D1) negative pole and the second diode (D2), the anodal and equal ground connection of the second diode (D2) negative pole of the first diode (D1); Described frequency selection circuit comprises the first resistance (R1), the first triode (Q1), the 3rd electric capacity (C3) and variable capacitance (VC1), described the first resistance (R1) end is connected with the base stage of the first triode (Q1), the first resistance (R1) connects the other end ground connection of the first triode (Q1) base terminal relatively, the link of filter circuit and frequency selection circuit is connected on the circuit between the first resistance (R1) and the first triode (Q1) base stage, the grounded emitter of the first triode (Q1), described the 3rd electric capacity (C3) and variable capacitance (VC1) formation in parallel parallel line, this parallel line one end is connected with the collector electrode of the first triode (Q1), and its other end is connected with signal output part (2).
2. the signal for frequency-modulation intercom for use according to claim 1 is inputted frequency-selector, it is characterized in that: described filter circuit comprises the first electric capacity (C1), the second electric capacity (C2) and the first inductance (L1), described the first inductance (L1) two ends respectively with the first electric capacity (C1) be connected electric capacity (C2) and be connected, the first electric capacity (C1) be connected electric capacity (C2) both relatively connect the other end ground connection of the first inductance (L1) end, described signal input part (1) is connected on the circuit between the first electric capacity (C1) and the first inductance (L1), and the link of described frequency selection circuit and filter circuit is connected on the circuit between the first inductance (L1) and the second electric capacity (C2).
3. the signal for frequency-modulation intercom for use according to claim 1 and 2 is inputted frequency-selector, and it is characterized in that: described the first triode (Q1) is the NPN triode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012203163651U CN202679547U (en) | 2012-07-03 | 2012-07-03 | Signal input frequency selector for frequency modulation interphone |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012203163651U CN202679547U (en) | 2012-07-03 | 2012-07-03 | Signal input frequency selector for frequency modulation interphone |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202679547U true CN202679547U (en) | 2013-01-16 |
Family
ID=47500416
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2012203163651U Expired - Fee Related CN202679547U (en) | 2012-07-03 | 2012-07-03 | Signal input frequency selector for frequency modulation interphone |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202679547U (en) |
-
2012
- 2012-07-03 CN CN2012203163651U patent/CN202679547U/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130116 Termination date: 20130703 |