JPH0522997Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present application relates to a transmission/reception switching circuit in a transceiver.

Conventional technology Generally, switching between transmitting and receiving with a transceiver is performed by pressing a switch attached to the microphone. For example, when using a transceiver while driving a car, the switch must be held down while transmitting. This means you have to drive with one hand, which is extremely dangerous.

For this reason, especially in transceivers for automobiles, a tumbler-type switch is used to switch between transmission and reception so that there is no need to hold down the switch during transmission.

However, this system has the disadvantage that if the switch is left in the transmitting state and left unattended for a long time, it may cause communication interference to other transceivers.

Conventionally, a transmission/reception switching circuit that automatically stops the transmission state after a certain period of time (approximately 3 minutes) has elapsed has been proposed in, for example, Japanese Utility Model Publications No. 60-40042 and No. 60-40043.

That is, if the above-mentioned known transmission/reception switching circuit is shown as a whole, it is as shown in FIG. 2, and in this circuit,
When the transmitting/receiving switch _S1 is switched to the transmitting side terminal, the switching transistor TR is turned on and enters the transmitting state, and the timer capacitor _C1 is charged via the resistors _R3 and _R4 .

And with the charging of capacitor _C1 , the said resistor
When the potential at the connection point between R ₃ and R ₄ reaches the threshold voltage of NAND circuit N ₁ , its output potential becomes L
level, and the first oscillation circuit consisting of a NAND circuit _N1 , a resistor _R5 , and a capacitor _C2 generates a buzzer _BZ.
emits a first alarm sound at a low frequency, then a second alarm consisting of a NAND circuit N ₂ , a resistor R ₆ and a capacitor C ₃
The oscillator circuit operates and emits a second alarm sound at a high frequency. On the other hand, the potential of capacitor C ₁ is this and resistor R ₄
When the threshold voltage of NAND circuit _N4 is reached with a time constant (approximately 3 minutes) determined by do.

Here, when continuing the transmitting state, the switch _S1 is quickly switched from the transmitting terminal T to the receiving terminal R to the transmitting terminal before the transmitting state is stopped.

Problems to be solved by the invention However, according to the above configuration, the switch S ₁
When switching from the transmitting side terminal to the receiving side terminal R,
The capacitor _C1 is grounded and discharged through the diode _D1 , resistors _R2 , _R1 and switch _S1 , but the potential difference of about 06V across the diode _D1 is not immediately discharged; Since the discharge occurs gradually via resistors R ₃ and R ₄ , the amount of discharge varies depending on how quickly switch S ₁ is operated, and the operating time of the timer circuit is therefore inconsistent, causing transmission to be interrupted. There was an inconvenience.

Therefore, the present application aims to solve the above-mentioned disadvantages of the conventional method.

Means for Solving the Problems In order to achieve the above-mentioned object, the present application provides, in the transmission/reception switching circuit of the transceiver that configures the transmission state and the reception state, respectively, when the transmission/reception switching switch is switched to the transmission side and the reception side, respectively. When the transmitting/receiving switch is switched to the transmitting side, a discharging circuit including a capacitor charged by the power supply voltage via the switch, a first timer circuit including a capacitor similarly charged by the power supply voltage, and a first timer circuit are connected. a second timer circuit that is activated by its output to stop the transmitting state of the transceiver after a time set by the circuit; and an oscillator circuit that activates a buzzer by the output from the first timer circuit. , the discharge circuit includes a diode connected in the forward direction with respect to the circuit capacitor, a first transistor having a base connected to the anode of the diode and an emitter connected to the cathode, and a base connected to the collector of the first transistor. connect, and
across the capacitor _C1 of the first timer circuit,
The device is characterized in that it is composed of a second transistor whose collector and emitter are respectively connected.

In the above, the setting time of the first timer circuit is set to about 2.5 minutes, and the setting time of the second timer circuit is set to about 0.5 minutes.

Function: When the transmitting/receiving switch is switched to the transmitting side, the transmitting state is entered, and the capacitor of the discharge circuit and the capacitor of the first timer circuit are respectively charged by the power supply voltage.

The set time of the first timer circuit is, for example, 2, 5.
After a minute, an H level output occurs, which activates the oscillator circuit and causes the buzzer to emit an alarm sound. On the other hand, the second timer circuit is activated by the H level output from the first timer circuit, and approximately 0.5 minutes after the set time, the switching transistor is activated to turn off by the output from the second timer circuit. The transmission status will automatically stop.

In the above, when the transmitting state is to be continued for more than 3 minutes, before the second timer circuit is activated and the transmitting state is stopped, the switch is quickly changed from the transmitting side to the receiving side to the transmitting side. Switch.

Here, when the switch is switched to the receiving side, the base potential of the first transistor of the discharge circuit decreases via the switch, but since the charging voltage of the capacitor of the discharge circuit is applied to its emitter, the first transistor 1 transistor is held in the ON state and collector current flows.

Since the base of the second transistor is connected to the collector of the first transistor,
The second transistor also maintains an ON state, and collector current flows. Since this collector current is supplied from the capacitor of the first timer circuit, the capacitor is instantaneously discharged to zero potential.

Therefore, regardless of the time at which the switch is switched, the first timer circuit always operates at a constant rate, and the transmission state can be continued with almost no time difference.

Embodiment The embodiment of the present application will be described below in detail based on the drawings. In the figure, when the switch S ₁ for switching between transmission and reception is switched to the transmission side terminal T, the switching transistor TR ₃ is turned ON and enters the transmission state. ,
A constant voltage of, for example, 9V is applied by a constant voltage circuit 1 consisting of a Zener diode ZD _{1 and} a resistor R 1 to a capacitor through a diode D ₁ of a discharge circuit 2 consisting of a diode D ₁ and transistors TR ₁ and TR ₂ .
A voltage of approximately 8.4V is applied to C ₂ , and the capacitor C ₂
is charged. _On the _other hand _{, a} first
Capacitor C ₁ of timer circuit 3 is connected to this and resistor R ₄
Charging is started with a time constant (for example, 2 to 5 minutes) determined by the above, and the potential at point C gradually rises.

Then, the potential at point C is Schmitt/Inverter
When the voltage rises to the threshold voltage of _Q1 , the potential at the output terminal d becomes H level, and the first oscillation circuit 4 consisting of the resistor _R9 , capacitor _C4 , and Schmitts/inverter _Q4 is activated, and the buzzer BZ is activated. A first alarm sound is emitted at a low frequency and then a second alarm sound is emitted at a high frequency by a second oscillator circuit 5 consisting of a resistor R ₁₀ , a capacitor C ₅ and a Schmitts/inverter Q ₆ .
Emit an alarm sound.

On the other hand, as the potential at point d becomes H level,
The second timer circuit 6 consisting of resistors R ₆ , R ₇ , _capacitor C ₃ and Schmitt/inverter Q ₃ starts operating and has _a time constant (approximately 0, 5 ) equivalent to the capacitor
When C ₃ is charged and the voltage at point e reaches the threshold voltage of Schmitt/inverter Q ₃ ,
The potential at the output terminal f becomes L level, the switching transistor _TR3 is turned off, and the transmission state is automatically stopped after about 3 minutes.

In the above, if the transmitting state is to continue for more than 3 minutes, the first alarm sound is emitted and before the transmitting state automatically stops, switch _S1 is connected from the transmitting terminal T to the receiving terminal as before. Terminal R → Sending side terminal T
This can be achieved by switching the switch _S1 to the receiving terminal R, the potential at point a decreases, and the base potential of the transistor _TR1 decreases.
Since the potential at point b is held at 8.4 V by the charging voltage of capacitor _C2 , transistor _TR1 is held in the ON state and collector current flows. Since the base of the transistor TR ₂ is connected to the collector of the transistor TR ₁ , the transistor TR ₂ also maintains an ON state, and a collector current flows _. Therefore, the capacitor _C1 is momentarily discharged to zero potential. Therefore, regardless of how quickly the switch _S1 is switched, the first timer circuit 3 always operates for a fixed period of time, and the transmission state can be continued with almost no time difference. In the figure, capacitor C ₆
The parallel circuit of D4 and diode _D4 is a circuit for removing external noise.

Effects of the invention As described above, according to the present application, the capacitor of the timer circuit that maintains the transmission state can be instantaneously discharged, so that the timer circuit can be This has the advantage that the transmission state can be continued properly without fear of causing a difference in operating time.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram according to an embodiment of the present application, and FIG. 2 is a conventional circuit diagram. In the figure, S ₁ is a switch, T is a transmitting side terminal, R is a receiving side terminal, D ₁ is a diode, TR ₁ and TR ₂ are transistors, C ₁ and C ₂ are capacitors, TR ₃ is a switching transistor, and BZ is a switching transistor. In the buzzer, 1 is a constant voltage circuit, 2 is a discharge circuit, 3 is a first timer circuit, 4 is a first oscillation circuit, 5 is a second oscillation circuit, and 6 is a second timer circuit.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) When the transmitter/receiver switch is switched to the transmitting side and the receiving side, in the transmitting switching circuit of the transceiver constituting the transmitting state and the receiving state, respectively,
When the transmitting/receiving switch is switched to the transmitting side, a discharging circuit including a capacitor charged by the power supply voltage via the switch, a first timer circuit including a capacitor similarly charged by the power supply voltage, and a first timer circuit are connected. a second timer circuit that is activated by its output to stop the transmitting state of the transceiver after a time set by the circuit; and an oscillator circuit that activates a buzzer by the output from the first timer circuit. , the discharge circuit includes a diode connected in the forward direction to the capacitor of the circuit, a first transistor having a base connected to the anode of the diode and an emitter connected to the cathode, and a base connected to the collector of the first transistor. and a second timer circuit having a collector and an emitter connected to both ends of the capacitor of the first timer circuit, respectively.
A transceiver transmission/reception switching circuit comprising a transistor. (2) The setting time of the first timer circuit is approximately 2.5 minutes.
2. The transmission/reception switching circuit for a transceiver according to claim 1, wherein the set time of the second timer circuit is set to approximately 0 and 5 minutes, respectively.