KR900010515Y1 - Muting circuitry using shorting type switch - Google Patents

Abstract

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Description

Muting circuit using shorted switch

Circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

5: output circuit S ₁ : function switching switch

S ₂ : Radio band selection switch S ₃ : Recording playback switch

P ₁ -P ₉ : Terminal R _1- R ₄ : Resistance

Q ₁ -Q ₃ : Transistor C ₁ -C ₄ : Capacitor

LS, RS: Speaker

The present invention relates to a muting circuit using a shorting switch to remove the noise generated during switch switching in the amplifier field by using a shorting type switch.

There are many muting circuits to remove noise generated when switching a switch, but the circuits that have been used a lot of them make noise removing terminals in addition to the main terminals of switches, and the noise removing terminals operate prior to the main terminals of switches. Since the muting transistor connected to the noise removing terminal is operated to remove the noise, the manufacturing cost rises and it is difficult to design.

In order to solve this problem, the present invention uses the terminals of a shorting type switch to be muted by driving a transistor when each terminal is momentarily connected (when switching). By providing a muting circuit that is simple in design and can reduce cost, the muting transistor is configured through a drive transistor at the moment of switching of the switch by configuring a function switch switch, a radio band selection switch, and a recording / playback switch. It is configured to be controlled.

This will be described in detail with reference to the accompanying drawings.

Audio output for outputting the left and right channel input signals applied to the input terminals (1) and (2) to the speaker LS and the RS through the DC blocking capacitor C5-C8 and the amplifier 3 and 4. In the circuit (5), a function switching switch (S ₁ ), a radio band selection switch (S ₂ ), and a recording / playback switch (S ₃ ) consisting of a shorting type switch in which all terminals are connected and switched to one terminal at the time of switch switching. ), A transistor Q ₁ driven at a switching instant at which all the terminals of the function switching switch S ₁ , the radio band selection switch S ₂ , and the recording / playback switch S ₃ are connected, and the transistor Q _1. And a condenser (C ₁ ) for delaying the driving time. Driving time of the transistor (Q ₁₎ by the output, and drive the amplifier (3) transistor (Q ₂₎ for muting a shear type of (4) (Q ₃₎ and said transistor (Q ₂₎ (Q ₃₎ of the It consists of a capacitor (C ₂ ) for delaying.

Here, the short type switch is a switch that is connected to one terminal after all terminals are temporarily connected at the time of switch switching.

In the present invention configured as described above, when the function switching switch (S ₁ ) is switched from the phono terminal (P ₆ ) position to the compact disk terminal (P ₇ ) position, the momentary switch (S ₁ ) of the switching function of the shorting type switch ( As P ₆ ) (P ₇ ) (P ₈ ) (P ₉ ) is momentarily connected, the nowood point B is connected to ground and instantaneously drops to the zero potential, so that the power supply Vcc is supplied to the emitter side. When the day side of the PNP transistor Q ₁ is in the "L level" state, the transistor Q ₁ is "turned on", and when the transistor Q ₁ is "turned on", the potential of the collector side (point C) is " H level ”and the bias voltage is supplied to the muting transistors Q ₂ and Q ₃ through the bias resistor R ₃ and Q ₃ so that the transistors Q ₂ and Q ₃ are turned on. The potential of the wood point D (F) becomes a "0" potential.

Therefore, since the left and right channel input signals applied from the input terminals 1 and 2 to the amplifiers 3 and 4 are not applied to the amplifiers 3 and 4, the left and right channel input signals are cut off, thereby performing a muting operation at the time of switch switching.

At this time, when switching the function selector switch (S ₁ ), the terminals (P ₆ ) (P ₇ ) (P ₈ ) (P ₉ ) are connected at the same time so that the drive transistor Q ₁ is 'turned on' for a very short time. By adding a condenser C ₁ (C ₂ ) with the shorting function switching switch S1 connected to the terminal R ₇ , the power supply Vcc continues to be charged for the condenser C ₁ while the transistor Q ₁ ) maintains the 'turn on' state, and the capacitor C ₂ delays the time when the charged charge is charged and the muting transistor Q ₂ (Q ₃ ) is 'turned on'.

That is, when switching the function selector switch S ₁ , the period in which all of the terminals P ₆ , P ₇ , P ₈ and P ₉ are connected is short, AO, and only during this period, the muting transistor Q ₂ ( Since Q ₃ ) is not enough to eliminate the noise generated during switch switching, the 'turn' time of transistors Q ₁ (Q ₂ ) (Q ₃ ) using capacitor C ₁ (C ₂ ) can be eliminated. By delaying, the muting transistor Q ₂ (Q ₃ ) is sufficiently turned on to 'turn on' to remove noise during switch switching.

Therefore, the muting time can be adjusted by using the capacitors C ₁ and C ₂ .

However, after the function switching switch S ₁ is completely separated from the terminals P ₆ , P ₇ and P ₈ and connected to the terminal P ₇ , the power supply Vcc is applied through the resistor R ₂ . The power supply Vcc is layered on the capacitor C ₁ and applied to the base side of the PNP transistor Q ₁ so that the transistor Q ₁ is cut off, the transistor Q ₁ is cut off, and the capacitor C ₂ is charged. When the discharged charge is discharged, the transistors Q ₂ and Q ₃ are in a blocking state, so the left and right channel input signals applied to the input terminals 1 and 2 of the output circuit 5 are DC blocking capacitors C ₅ ( C ₆ ) is amplified by the amplifiers 3 and 4 and then output to the left and right speakers LS and RS.

On the other hand, the radio band selection switch (S ₂ ) and the recording and playback switch (S ₃ ) are also configured as shorting switches. When the radio band selection switch (S ₃ ) is switched, the terminals (P ₃ ) (P ₄ ) (P ₅ ) It is connected instantaneously and the terminal P ₁ (P ₂ ) is instantaneously connected even when the recording / playback switch S ₃ is switched, and therefore, even when the radio band selection switch S ₃ and the recording / playback switch S ₃ are switched. to function change-over switch (S ₁₎ 'turned on' the driver transistor (Q ₁₎ 'turned on "by the transistor (Q ₂₎ for muting the (Q _3), such as when switching of that may eliminate noise generated during switching changeover will be.

As described above, the present invention is simple to design and low cost by constructing a muting circuit using a short type switch that is connected to all terminals at the moment of switch switching and is widely applied to low-cost home appliances. There is an effect that can be made.

Claims (1)

In an audio output circuit in which left and right channel input signals are amplified by the amplifiers 3 and 4 and output to the speaker LS and RS, a shorting type in which all bullets are connected and switched to one terminal at the time of switching. A function switching switch (S ₁ ), a radio band selection switch (S ₂ ) and a recording / playback switch (S ₃ ) configured as a switch, the function switching switch (S ₁ ), a radio band selection switch (S ₂ ), and a recording playback by a switch (S ₃₎ all the terminals connected to the switching moment the driver transistor (Q ₁₎ which is in the, and a capacitor (C ₁₎ for delaying the operating time of the transistor (Q _1), the transistor (Q ₁₎ output transistor (Q ₂₎ for driving and muting the front end input of the amplifier (3) (4) (Q 3) and said transistor capacitor for delaying the operating time of the _{(Q 2) (Q 3)} (C 2) consisting show Muting circuit using floating switch.