JPS5919493Y2 - Input/output separation circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an input/output separation circuit used in transceivers, interphones, etc.

Conventionally, this type of input/output separation circuit has used a manual mechanical switch, but in actual use, the disadvantage was that it was cumbersome to switch the switch between when transmitting and when receiving a call. .

The present invention provides an input/output separation circuit that can automatically switch between transmitting and receiving calls, thereby eliminating the problems of the prior art.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an input/output separation circuit diagram of an embodiment of the present invention.

101 is an input terminal, 102 is an output terminal, 103 is an input/output terminal, and 104 is a power supply terminal.

The base terminal A of the transistor 4 has an input capacitor 1 connected to the input terminal 101, and one end is connected to the power supply terminal 104.
The other end of each of the resistor 2 and the resistor 3, one end of which is grounded, is connected to the other end of the resistor 2 .

Connected in series to the emitter terminal of the transistor 4 are a bias circuit 5 in which a resistor 6 and a capacitor 7 are connected in parallel, and a transformer 13 having a secondary winding 14 whose one end is grounded.

Resistors 9 and 10 are connected between the connection point between the bias circuit 5 and the secondary winding 14 of the transformer 13 and the collector terminal of the transistor 4.
are connected in series and are connected to a resistor network 8 having a dividing point 17.

Further, a load resistor 11 whose one end is connected to a power supply terminal 104 is connected to the collector terminal.

The input/output terminal 103 is connected to the primary winding 15 of the transformer 13.
An electroacoustic transducer element 16 is connected via.

Next, the operation will be explained.

A bias voltage obtained by dividing the power supply voltage of the power supply terminal 104 into a predetermined voltage is applied to the base terminal A of the transistor 4 by the resistors 2 and 3.

When the input signal of the input terminal 101 is applied to the base terminal A, the amplified signal is applied to the secondary winding 14 of the transformer 13 from the emitter terminal via the bias circuit 5.

A signal induced in the primary winding 15 by the voltage applied to the secondary winding 14 and whose impedance is converted is sent to the input/output terminal 10.
3 to the electroacoustic transducer 16, resulting in a predetermined audio output.

Here, the phase of the voltage of the output signal to the collector terminal of the transistor 4 whose one end is connected to the power supply terminal 104 and the other end of the load resistor 11 is connected is opposite to the phase of the voltage of the output signal at the emitter terminal port. Become a phase.

Therefore, if the dividing point 17 of the resistor network 8, which is connected between the connection point of the bias circuit 5 and the secondary winding 14 of the transformer 13 and the collector terminal and is made up of the series connection of resistors 9 and 10, is selected appropriately, the emitter The signal that goes from the terminal port to the resistor 9 via the bias circuit 5 is canceled out by the signal that goes from the collector terminal C to the resistor 10, and is sent to the output terminal 102 connected to the connection point between the resistors 9 and 10 via the capacitor 12. No signal appears.

Next, the audio signal converted by the electroacoustic transducer 16 is applied to the primary winding 15 of the transformer 13 via the input/output terminal 103.

As a result, the output signal boosted and induced in the secondary winding 14 is applied to the output terminal 102 via the resistor 9 of the resistor network 8 and the capacitor 12.

In this case, no output signal appears at the input terminal 101 due to the directionality of the operating characteristics of the transistor 4.

When used in an actual product, it is better to configure the resistance network 8 with a variable resistor and connect the output terminal 102 to the sliding terminal via the capacitor 12. Variations can be absorbed by this sliding resistor, resulting in a more practical circuit configuration.

As explained above, the present invention has a circuit configuration in which a signal that goes around from an input terminal to an output terminal is canceled out by a signal having an opposite phase relationship in an input/output separation circuit used in transceivers, interphones, etc. By doing so, it is possible to automatically switch between transmission and reception, and it is possible to eliminate the complicated switching operation when using a conventional mechanical switch.

[Brief explanation of drawings]

FIG. 1 shows an input/output separation circuit diagram of an embodiment of the present invention. 4...Transistor, 5...Bias circuit, 8...Resistance network, 11...Load resistance, 13...Transformer, 14...2
Next winding, 15...Primary winding, 16...
Electroacoustic conversion element, 17... Division point, i...
...Base terminal, mouth...Emitter terminal, C
...Collector terminal.

Claims (1)

[Scope of utility model registration request] In a device in which a single electroacoustic transducer element serves both the functions of a microphone and a speaker or earphone, a transistor that amplifies an input signal applied to a base terminal and input/output signals to and from the electroacoustic transducer element are provided. a transformer for impedance matching and serving as a load on the emitter side of the transistor; a bias circuit for the transistor connected in series with a winding of the transformer; and a load on the collector side of the transistor. a load resistor connected in series with the bias circuit between the collector terminal and emitter terminal of the transistor, and a dividing point at which the signals obtained at the emitter and collector terminals are canceled out with respect to the input signal applied to the base terminal. an input signal applied to the base terminal is taken out from the emitter terminal and applied to the electroacoustic transducer through the bias circuit and the transformer, and the input signal applied to the base terminal is applied to the electroacoustic transducer, and the input signal applied to the base terminal is applied to the electroacoustic transducer. An input/output separation circuit characterized in that a signal can be extracted from a dividing point of the resistor network.