JPS6119176B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a tuning indicating device that uses the same meter as a tuning meter that indicates the balance of the S-shaped output of the FM detection output and a signal meter that indicates the intensity of the FM intermediate frequency output. The purpose of this invention is to configure the meter so that the signal applied to the meter can be automatically switched, thereby significantly facilitating the tuning operation.

In general, FM receivers configured to function as both a tuning meter and a signal meter are well known, but in all of these types of receivers, the signal applied to the meter is switched by manual operation. This was extremely inconvenient when performing a series of tuning operations.

In other words, in general, if an FM receiver equipped with a tuning meter and a signal meter is significantly out of tune, it is convenient to approach the tuning point while watching the signal meter. Since the limiter effect of the intermediate frequency amplification circuit slows down the signal meter's performance, it is convenient to find the optimum tuning point while looking at the tuning meter. Therefore, from this point of view, tuning meters and signal meters are often used together, but in this case, conventionally, the signal applied to the meter was switched by manual operation; The problem was that it was very troublesome.

The present invention eliminates the above-mentioned conventional drawbacks, and automatically switches the signal applied to the meter according to the output level of the intermediate frequency amplifier circuit, thereby significantly simplifying the tuning operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The tuning instruction device of the present invention will be described below with reference to drawings of embodiments.

FIG. 1 is an electrical wiring diagram of one embodiment of the tuning instruction device of the present invention, in which a is the input terminal to which the S-shaped output of the FM detection circuit is applied, and b is the above-mentioned input terminal.
Input terminal to which the midpoint voltage of the S-shaped output of the FM detection circuit is applied as a reference voltage, c is the input terminal to which the rectified output of the FM intermediate frequency amplification circuit is applied, and d is the input terminal to which the control signal from the control signal generation circuit is applied. In this case, the control signal generation circuit consists of a series circuit of two resistors inserted between the rectified output terminal of the FM intermediate frequency amplifier circuit and the ground, and the control signal is generated from the above two connection points. Configured to be removed. And Q ₁ ~ _{Q 3} are transistors, R ₁ ~
R ₄ is a resistor, D ₁ and D ₂ are diodes, M is a meter,
_Vcc is a DC power supply.

In Fig. 1, when the tuning is largely out of tune, the rectified output of the intermediate frequency amplifier circuit is zero or very small, so the signal applied to input terminal d is also zero or very small, and transistor Q ₂ is turned off. in a state. Therefore, in this case, the potential at the collector of transistor Q ₂ is approximately at V _cc potential, and both transistors Q ₁ and Q ₃ are in an on state. Therefore, if FM is connected between input terminals a and b,
Even if the S-shaped outputs of the detection circuit are applied, they are grounded by the transistors Q ₁ and Q ₃ and are not applied to the meter M. In this case, the rectified output of the intermediate frequency amplifier circuit applied to input terminal c is connected to diode D ₂ , meter M, and transistor Q ₃
The meter M will give an indication according to the rectified output.

This state is maintained until the control signal applied to the input terminal d exceeds a certain value and the transistor _Q2 is turned on, that is, until the transistor Q2 approaches the tuning point to some extent. Then, when the tuning point is approached to some extent and the control signal applied to the input terminal d exceeds a certain value, the transistor _Q2 is turned on and its collector potential becomes equal to the ground potential.

Therefore, in this state, the rectified output of the intermediate frequency amplifier circuit applied to input terminal c is
D ₁ is grounded via transistor Q ₂ and the rectified output is no longer applied to meter M. In this state, more transistors
With Q ₂ turned on, transistors Q ₁ and Q ₃
is turned off, the S-shaped output of the FM detection output applied to the input terminal a is applied to the meter M, and the meter M gives an instruction according to the S-shaped output.

In this way, according to the above embodiment, the meter M operates as a signal meter while the tuning is largely out of tune, and automatically operates as a tuning meter when it approaches the tuning point to a certain extent. There is no need to manually switch between
The tuning operation itself can be significantly simplified.

In the embodiment shown in FIG. 1, an input terminal d is separately provided to apply the rectified output of the intermediate frequency amplifier circuit as a control signal, but as shown in FIG. A series circuit of resistors R ₅ and R ₆ may be provided, and a connection point between the resistors R ₅ and R ₆ may be applied to the base of the transistor Q ₂ .
Furthermore, if a light emitting diode _D0 is provided between the _Vcc power supply and the collector of the transistor _Q2 , the light emitting diode _D0 will light up at the same time when the transistor _Q2 is turned on near the tuning point, so this light emitting diode _D0 The tuning point approaches depending on the lighting condition of
This will indicate that the meter M is operating as a tuning meter.

As is clear from the above embodiments, the tuning instruction device of the present invention has a simple configuration and automatically performs tuning when the meter that operates as a signal meter approaches the tuning point when the tuning is largely out of tune. It can be switched to operate as a meter, and there is no need to manually switch these switches each time during tuning, making the tuning operation itself extremely simple.

[Brief explanation of the drawing]

FIG. 1 is an electrical wiring diagram of one embodiment of the tuning instruction device of the present invention, and FIG. 2 is an electrical wiring diagram of another embodiment. a to d...Input terminal, _Q1 to _Q3 ...Transistor, _R1 to _R7 ...Resistor, _D1 to _D3 ...Diode,
D ₀ ... Light emitting diode, M... Meter.

Claims (1)

[Claims] 1. A meter is connected between the input terminal to which the S-shaped output of the FM detection circuit is applied and the input terminal to which the midpoint voltage of the S-shaped output of the FM detection circuit is applied, and the intermediate frequency The input terminal to which the rectified output of the amplifier circuit is applied is connected to one input terminal of the meter to which the S-shaped output is applied, and the first, second, and third terminals are connected between these input terminals and the ground, respectively. Transistors are connected, and the first, second, and third transistors are turned on and off by a control signal related to the rectified output of the intermediate frequency amplification circuit that is applied to a separately provided input terminal, and tuning is performed. If there is a large deviation, the first transistor is connected between the input terminal to which the S-shaped output of the FM detection circuit is applied and the ground, and the input terminal to which the midpoint voltage of the S-shaped output is applied and the ground. The third transistor connected between the input terminal to which the rectified output of the intermediate frequency amplifier circuit is applied and the ground is turned off, thereby rectifying the intermediate frequency amplifier circuit. A tuning instruction device configured to apply an output to the meter, and when the tuning point approaches the tuning point to some extent, reverse the operations of the first to third transistors and apply the S-shaped output of the FM detection circuit to the meter. . 2. The control signal according to claim 1, characterized in that the control signal is taken out from a dividing point of a resistor connected between the input terminal to which the rectified output of the intermediate frequency amplifier circuit is applied and the ground. Tuning instruction device. 3 Connect a meter between the input terminal to which the S-shaped output of the FM detection circuit is applied and the input terminal to which the midpoint voltage of the S-shaped output of the FM detection circuit is applied, and measure the rectified output of the intermediate frequency amplifier circuit. Connecting the input terminal to which the S-shaped output is applied to one input terminal of the meter to which the S-shaped output is applied, and connecting first, second, and third transistors between these input terminals and ground, respectively; These first, second, and third transistors are controlled on and off by control signals related to the rectified output of the intermediate frequency amplifier circuit that are applied to separately provided input terminals, and when the tuning is significantly out of tune, A first transistor connected between an input terminal to which the S-shaped output of the FM detection circuit is applied and ground, and a first transistor connected between the input terminal to which the midpoint voltage of the S-shaped output is applied and ground. The second transistor is turned on, and the third transistor connected between the input terminal to which the rectified output of the intermediate frequency amplifier circuit is applied and the ground is turned off, and the rectified output of the intermediate frequency amplifier circuit is connected to the meter. When it approaches the tuning point to some extent, the operation of the first to third transistors is reversed and the S-shaped output of the FM detection circuit is applied to the meter, making it a signal meter. A light emitting diode is connected between the collector of the third transistor and the _Vcc power supply, and depending on whether the light emitting diode is turned on or off, the meter operates as a signal meter or as a tuning meter. a tuning instruction device configured to display whether the