JPH0145161Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an unstable multivibrator that oscillates pulses at a natural frequency.

A general unstable multivibrator oscillates a pulse at a natural frequency when the start switch is turned on, and stops operating when the switch is turned off, but even if the switch is turned off and then turned on again, the Pulses are not necessarily generated following the ON operation completely. In other words, as shown in Fig. 1, when the switch is turned on at time _t1 , from that point on, the output of the unstable multivibrator is at the binary logic level L (hereinafter simply referred to as L. Also, the binary logic level H is A pulse (simply referred to as H) is generated, and as long as the switch is kept on, the L pulse is generated at a natural period, but at time t ₂ the switch is turned off, and some time later, at time t ₃ , the switch is turned on. Even so, there will be no L pulse at the output until further time has elapsed for charging or discharging the capacitor in the astable multivibrator. That is, in the conventional unstable multivibrator, when the switch is repeatedly turned on and off at intervals within the natural oscillation period, the output cannot follow the operation.

An object of the present invention is to provide an unstable multivibrator that generates a pulse in the output even if the switch is repeatedly turned on and off in a short period of time, the output always follows the on-off operation.

The present invention will be explained below with reference to examples. FIG. 2 is a diagram showing a circuit of an embodiment of an astable multivibrator. The non-inverting input terminal of operational amplifier 1, whose amplification factor can be considered infinite, has a power supply voltage +
Vcc is divided and given by resistors R ₁ and R ₂ , and the output voltage V ₀ is divided by resistor R ₃ .
It is now possible to receive positive feedback. On the other hand, the output voltage V ₀ is integrated by a capacitor C and applied to the inverting input terminal, and this capacitor C is connected to a resistor R ₄ or a diode D ₁ and a resistor.
It is designed to be charged via R ₅ and discharged via resistor R ₄ or diode D ₂ and resistor R ₆ . Then, the values of resistors R ₄ to _{R 6} are set as R ₄ 》R ₅ ,
By selecting R ₆ , charging time constant T ₁ = C・
The relationship between R ₄ and T ₂ =C·R ₅ is set as T ₁ >>T ₂ . Note that since the discharge time constant T ₃ is R ₄ >>R ₆ , it can be considered that T ₃ =C·R ₆ .

2 is a non-lock type switch for starting operation, and by turning on switch 2, the power supply voltage +Vcc is divided by resistors R ₇ and R ₈ and applied to the base of the switching transistor Q, and that transistor Q is now turned on. This transistor Q has its collector and emitter connected between the above-mentioned resistor R ₂ and the ground, and its ON operation causes the potential at the common connection point of the resistors R ₁ and R ₂ to be reduced, that is, the non-inverting input of the operational amplifier 1. potential V ₊ ,
Switch to a slightly lower potential. In addition, the collector of this transistor Q is connected to the common connection point of the resistor _R5 and the diode _D1 , and when it turns on, the common connection point is grounded, and the capacitor C consisting of the resistor _R5 and the diode _D1 is connected. disables the charging function of the charging path.

Next, the operation will be explained with reference to the timing chart shown in FIG. First, while switch 2 is off, transistor Q is off, so the voltage at the non-inverting input terminal of operational amplifier 1 is
V ₊ is a high voltage that is the power supply voltage + Vcc applied via resistor R ₁ , while the voltage at the inverting input terminal is
V _- is the output voltage of operational amplifier 1 when capacitor C is V ₀
By being charged to (H), the voltage value becomes the same level as the output voltage, but V ₊ 〉
The constants are selected so that the V _- relationship is maintained, and the output is in the H state.

Next, when switch 2 is turned on in this state, transistor Q is turned on and diode D ₁ and resistor R ₅
The common connection point of will drop to ground, and the voltage at the non-inverting input terminal, V ₊ , will drop below the voltage at the inverting input terminal _, V-. Therefore, the state of the operational amplifier 1 is reversed, and the output becomes L. Therefore, the charge on the capacitor C is discharged toward the output terminal via the diode D ₂ and the resistor R ₆ with a time constant of T ₃ =C·R ₆ . Note that the resistance R ₄ is R ₄ >>R ₆ , so the path can be ignored. Also, since resistor _R5 is in series with _R6 , this can also be ignored. In addition, the voltage V ₊ of the non-inverting input terminal is the resistance of the output voltage that has become L level.
Received through R ₃ , its level drops significantly. Then, as the discharge progresses and the voltage of the capacitor C decreases, and the voltage V _- at the inverting input terminal becomes less than the voltage V ₊ at the non-inverting input terminal, the operational amplifier 1
The state returns to its original state and the output becomes H. Therefore, charging of the capacitor C starts via the resistor R ₄ with a time constant of T ₁ =C·R ₄ . Further, since the voltage V ₊ at the non-inverting input terminal receives the output voltage that has reached the H level via the resistor R ₃ , its level increases. Then, as charging of the capacitor C progresses and its voltage rises, and the voltage V _- at the inverting input terminal exceeds the voltage V ₊ at the non-inverting input terminal, the state of the operational amplifier 1 is inverted again. The above operation is repeated, and the output is L.
A level pulse is continuously generated with a pulse width determined by the time constant _T3 and a period determined by the time constants _T1 and _T3 as long as the switch 2 is turned on. Note that the voltage of capacitor C when switch 2 is off is slightly higher than the voltage when switch 2 is on and repeats the oscillation operation, so in the former case, it takes a little longer to discharge to a predetermined level. The pulse width of the L pulse immediately after the switch 2 is turned on becomes longer than the pulse width that occurs thereafter.

Next, when switch 2 is turned off while the output is H, transistor Q is turned off, and the voltage V ₊ at the non-inverting input terminal further increases.
The common connection point between resistor R ₅ and diode D ₁ is lifted from ground, and charging to capacitor C is performed through its resistor R ₅ (《R ₄ ) and diode instead of through the charging path of resistor R ₄ .
It is now carried out via the _D1 route. Therefore, the charging time constant changes from T ₁ = C・R ₄ to T ₂ = C・
Since T _{1 >>} T ₂ in this case, the capacitor C is quickly charged and the voltage V _- at the inverting input terminal changes within a short time after switch 2 is turned off. Becomes high potential. However, since the voltage V ₊ at the non-inverting input terminal is at a higher potential when the switch 2 is turned off, the state of the operational amplifier 1 does not change.

As described above, if switch 2 is turned off when the output is H, the voltage at the inverting input terminal V _-
becomes a high potential, so even if switch 2 is turned off and then turned on again, the voltage V _- at the inverting input terminal is already at a high potential when it is turned on.
The state of the operational amplifier 1 is reversed and an L pulse is generated. In other words, conventionally, even if the off->on operation is performed as described above, the time constant after the previous L pulse disappears until the next L pulse is generated.
At least the elapse of time corresponding to T ₁ =C·R ₄ was required, but this is completely unnecessary.

Note that the time required from turning off switch 2 (e.g., releasing your hand) to turning it on (e.g., pressing it) usually requires at least 200 ms.
If the charging time constant T ₂ is set appropriately so that the time until the capacitor C is fully charged by the charging time constant T ₂ is less than 200 ms, it is possible to repeat the on/off operation by human operation. too,
An L pulse always occurs during the ON operation.

On the other hand, if switch 2 is turned off when the output is L, contrary to the above case, the level of the voltage V ₊ at the non-inverting input terminal, which has decreased in level due to the feedback of the output L, will slightly decrease. Since the amount of charge discharged from the capacitor C is smaller than that during normal oscillation operation, the voltage V _- at the inverting input terminal becomes lower than the voltage V ₊ , and the L pulse width becomes slightly narrower. In this case, if the ON operation is immediately performed, it seems that a new pulse that follows it does not occur, but since it takes about 200ms as mentioned above from the OFF operation to the ON operation, the L pulse during normal operation Set the pulse width setting to be narrow enough, e.g.
If the setting is set to about 10 ms, a new L pulse will be generated following the ON operation without any problem.

The above is an example of an unstable multivibrator in which an L pulse is generated on the output side, but the same idea can be applied to a case in which an H pulse is generated on the output side, although the details are omitted. It can be realized.

As described above, according to the present invention, even if the time interval between the on/off operations of the switch is narrower than the natural oscillation period of the unstable multivibrator, a pulse is always generated when the switch is turned on. Therefore, when used in a remote control device where the slide switches at predetermined time intervals in response to the oscillation pulses of the unstable multivibrator as long as the switch is pressed, by turning the switch off and on in a short period of time, Slides can be switched at time intervals shorter than the predetermined time interval. This is just one example, but it can also be used for remote control of TV channel switching and other purposes.

[Brief explanation of the drawing]

Fig. 1 is a timing chart of the operation of a conventional non-stable multivibrator, Fig. 2 is a circuit diagram of an embodiment of the non-stable multivibrator of the present invention, and Fig. 3 is a timing chart of the operation of a conventional non-stable multivibrator.
The figure is a timing chart of the operation of the circuit of FIG. 1... operational amplifier, 2... switch.

Claims (1)

[Scope of utility model registration request] an operational amplifier; a first resistor connected between the output terminal and the non-inverting input terminal of the operational amplifier; and a second resistor connected between the inverting input terminal and the output terminal of the operational amplifier. and a third resistor connected in series between the inverting input terminal and the output terminal with a first diode having the inverting input terminal as an anode, and between the inverting input terminal and the output terminal. a fourth resistor connected in series with a second diode having the inverting input terminal as its cathode, a capacitor connected between the inverting input terminal and ground, and the first output pole and the power supply. fifth and sixth resistors are connected in series, the first output pole is connected to a common connection point between the second diode and the fourth resistor, and the second output pole is grounded. comprising a transistor and a switch for turning on the transistor, a common connection point of the fifth and sixth resistors is connected to the non-inverting input terminal;
and the resistance value of the second resistor is set to the third and fourth resistors.
An unstable multivibrator characterized by having a resistance value set higher than the resistance value of the resistor.