JPS5928471Y2 - Siren oscillator starting circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an emergency siren activation circuit that amplifies the output frequency of a voltage controlled oscillator.

Specifically, the present invention provides a starting circuit that shortens the time from when the siren starting switch is turned on to when the siren sound is generated.

Emergency sirens using voltage-controlled oscillators have been in practical use for some time, but a slow charging voltage to a capacitor is used as the output frequency control signal of the voltage-controlled oscillator.
The output frequency control signal changes from zero to a predetermined voltage range due to conduction of the siren activation switch, but since the voltage controlled oscillator does not produce an output and requires a constant voltage as the output frequency control signal, the siren activation switch is activated. In this case, the output frequency control signal rises to a constant voltage when the starting switch is turned on, and the voltage controlled oscillator does not produce an output, which has the disadvantage that a siren sound is generated a little later than when the starting switch is turned on.

For emergency sirens used in emergency situations, the delay in generating the siren sound is a serious disadvantage.

The present invention has been devised in view of the above-mentioned circumstances.

The present invention will be explained below based on the drawings.

1 is a power supply terminal, 2 is a starting circuit, 3 is a voltage controlled oscillator whose output frequency is changed by a control signal of the starting circuit 20, 4 is an amplifier that amplifies the output of the voltage controlled oscillator 3, and 5 is a speaker.

The starting circuit 2 is the collector voltage source terminal 1 of the transistor Q1.
The emitter is connected to the output frequency control signal of the voltage controlled oscillator 3, the base is grounded via the capacitor C, and the base is connected to the resistor R1 and the transistor Q2.
It is connected to the power supply terminal 1 via a constant current circuit 8 and a starting switch 6 in series, and is also connected to a voltage circuit 9 via a diode D.

The voltage circuit 9 connects the power supply terminal 1 and the ground with resistors R2*R3
tR4 are connected in series, and the voltage applied to the power supply terminal 1 is divided appropriately.

T is a switch that works in conjunction with the starting switch 6, and short-circuits the resistor R4 when the starting switch 6 is non-conducting. The divided voltage is set low during non-ring conduction.

Next, the operation will be explained.

In conventional practical devices, the capacitor starts charging from zero when the start switch is turned on, and the minimum signal V necessary for the voltage controlled oscillator to generate an output is generated as shown in Figure 2A.
2, the terminal voltage of the capacitor increases at t.

period.

Generation of the siren sound is delayed by this period of to.

In the present invention, if the terminal voltage applied from the voltage circuit 9 to the capacitor C via the diode D when the starting switch 6 is non-conductive is Vl, the capacitor C is charged from the V1 voltage due to the conducting of the starting switch 6, and the terminal voltage v2
It will take tl time to rise to .

Voltage ■1 is voltage control generator circuit 3 and resistors R2, R3, R
4 is set slightly lower than V2 in consideration of the variation in V2.

Furthermore, when the starting switch 6 is turned on, the divided voltage of the voltage circuit 9 is reduced to approximately V2 by the switch I that is linked to the starting switch 6.
Then, in the case where capacitor C reaches V2, current flows through both constant current circuit 8 and resistor R2,
■The charging period 2 is shorter than t2.

After capacitor C is charged to V2, constant current circuit 8
A slow charge is made through the .

The diode D prevents reverse current when the capacitor C is charged at a higher potential than the divided voltage of the voltage circuit 9.

Transistor Q1 is a buffer for the signal appearing on capacitor C.

As described in detail above, in the present invention, a constant voltage is applied to the capacitor in advance when the starting switch is not conducting, and charging is started from the constant voltage when the starting switch is turned on, so that charging is performed slowly. Despite the fact that
This shortens the time it takes for the voltage-controlled oscillator to produce an output when the starting switch is turned on, and the siren sound can be generated by ensuring that the starting switch is turned on.In practice, the effect is significant.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the invention. FIG. 2 is an explanatory diagram showing the rise in terminal voltage of capacitor C due to conduction of the starting switch. 2... Starting circuit, 3... Voltage controlled oscillator, 6...
Start switch, 9...voltage circuit, C...capacitor, D...diode.

Claims (1)

[Scope of utility model registration request] In a starting circuit for a siren oscillator using a voltage controlled oscillator, a capacitor that is slowly charged by conduction of a siren starting switch and a voltage circuit that applies a constant voltage to this capacitor via a diode are provided, and the terminal voltage of the capacitor is A starting circuit for a siren oscillator, characterized in that a voltage according to the voltage is applied to a control terminal for controlling the output frequency of the voltage controlled oscillator.