JPH0410709A - Astable multivibrator - Google Patents

Abstract

PURPOSE:To set up a duty ratio in a wide range without increasing the number of parts by inserting diodes into a charging/discharging circuit consisting of a capacitor determing the duty ratio of an output and resistor circuits and changing the resistance values of the resistor circuits in accordance with inflow of current into one pole of the capacitor or the outflow of current from the one pole. CONSTITUTION:The diodes D1, D2 are inserted into the charging/discharging circuit consisting of the capacitor CT determining the duty ratio of the output and the resistor circuits RT1, RT2 and the resistance values of the resistor circuits are changed in accordance with the inflow of current into one pole of the capacitor or the outflow of current from the one pole. Namely, the resistors RT1, RT2 connected in parallel are connected to the output terminal of astable multivibrators 1 to 3 and the anode of the diode D1 and the cathode of the diode D2 are respectively connected to the other therminals of the resistors RT1, RT2. Thereby, duty ratio can be optionally and independently set up during the charging/discharging time of the capacitor CT by selecting the resistance values of the resistors RT1, RT2. Thus, the duty ratio can be set up in a wide range.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to an astable multivibrator.

[Prior art and its problems] Conventionally, a simple astable multivibrator as shown in Fig. 5 (
The one shown in a) is commonly used.

That is, the capacitor C1 is charged and discharged via the resistor RT connected to the output terminal PO, and the voltage level of the pole of the capacitor CT connected to the resistor RT is changed via the stabilizing resistor RS to the input terminal P1. and the output is the fifth
As shown in Figure (b), it becomes a square wave in which the time T1 between high level and the time T2 between low level are equal. In this case, TI=T2=kIC)R1 where 1 is a coefficient (~1.1) determined by the frequency and the element.

By the way, this type of astable multivibrator cannot set the above-mentioned time TI and the above-mentioned time T2 independently, that is, cannot change the duty ratio, and when a square wave with a changed duty ratio is required, , a method has been adopted in which other circuits are connected to the astable multi-byte break. For example, 1. The output of the astable multivibrator is input to a monostable multivibrator, and the capacitance of the external capacitor/resistor of the monostable multivibrator is
There is a method of adjusting the resistance value and making the monostable multi-bibreak continuously output an output of a desired pulse width (time T+) at a desired interval (time T2), or by adding a delay circuit and an AND gate. A method has been used to obtain the logical product of the output of an astable multivibrator and the output obtained by adding a certain delay to the output.

However, these methods have the problem that, for example, the addition of a monostable multivibrator or delay circuit increases the number of components, that is, the number of required IC points5, which in turn complicates the structure and increases current consumption. Ta.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide an astable multivibrator whose duty ratio can be set over a wide range without increasing the number of parts.

[Summary of the Invention] In order to achieve the above object, the present invention introduces a diode into a charging/discharging circuit consisting of a capacitor and a resistor circuit that determines the duty ratio of the output in an astable multivibrator. The gist is that the resistance value of the resistor circuit is changed depending on when a current flows into one pole of the resistor circuit and when a current flows out from the one pole.

[Example] The present invention will be specifically described below with reference to Examples shown in the drawings.

FIG. 1(a) shows a circuit configuration of a first embodiment of the present invention. That is, the output terminal of the front stage inverter 1 is connected to the input terminal of the middle stage inverter 2, and the middle stage inverter 2 is connected to the input terminal of the middle stage inverter 2.
The output terminal of is connected to the input terminal of the rear-stage inverter 3, and the output terminal of the latter-stage inverter 3 serves as the output terminal of the astable multivibrator. Resistors R11 and RT2 are connected in parallel to the output end of the rear-stage inverter 3, the anode of a diode DI is connected to the other end of the resistor RTI, and the cathode of a diode D2 is connected to the other end of the resistor RT2. Further, the cathode of the diode D1 and the anode of the diode D2 are connected to the other pole side of the capacitor cr, one pole of which is connected to the input terminal of the middle stage inverter 2, and the other pole side of the capacitor CT is stable. It is connected to the input terminal of the front-stage inverter l via the switching resistor R3.

In this embodiment configured as described above, when the output of the rear-stage inverter 3, that is, the output of the astable multivibrator, is at a high level, the output of the middle-stage inverter 2 is at a low level, and the current is changed to the output of the rear-stage inverter 3. The current flows from the terminal to the resistor RTI to the diode D1 to the capacitor CT to the output terminal of the middle stage inverter 2, and this current is controlled by the resistance value of the resistor RH. As the capacitor C1 is charged by the above-mentioned current, and the potential at the input terminal of the front-stage inverter 1 exceeds the threshold level of the front-stage inverter 1, all outputs of the front-stage inverter 1, middle-stage inverter 2, and rear-stage inverter 3 are Invert. As a result, the output of the rear stage inverter 3, that is, the output of the astable multi-by-break, becomes a high level, and the output of the middle stage inverter 2 becomes a high level. Therefore, the potential of the pole of the capacitor CT connected to the stabilizing resistor R3 is the same as the high level potential of the capacitor CT. tt This is the sum of the position differences. Therefore, the potential at the input terminal of the front-stage inverter 1 becomes significantly higher than this threshold level, and the current flows from the output terminal of the middle-stage inverter 2 to the capacitor C.
1→diode D2→resistance RT2→output terminal of the subsequent inverter 3, and this current is controlled by the resistance value of the resistor RT2. Due to the above-mentioned initial discharge current, the discharge of the capacitor CT and the charging after polarity reversal proceed, and the potential at the input end of the front-stage inverter 1 also decreases, but the potential at the input end of the front-stage inverter 1 decreases. When becomes below the threshold level of the front-stage inverter 1, the outputs of the front-stage inverter 1, middle-stage inverter 2, and rear-stage inverter 3 are inverted. Therefore, the stabilizing resistance R of the capacitor cr
The potential of the pole connected to C1 is the low level potential minus the potential difference at the capacitor C1. Therefore, the potential at the input terminal of the front-stage inverter 1 becomes significantly lower than this threshold level, and the current also increases from the resistor RTI.
, returns to flowing into the capacitor C1 through the diode D1. In the above operation, if the time during which the output of the subsequent inverter 3 is at high level is TI, and the time during which it is at low level is T2, then times T+, T2
is expressed as follows.

T1 = k2acr RTI T2 = k2bcTRT2 (k2a, k2b are constants) As can be seen from the above two equations, the time T1 when the output of the astable multi-noise oscillator is at the noise level and the time T2 when it is low level are determined by the resistance RTI, It can be set arbitrarily and independently by selecting the resistance value of RT2.

For example, if the resistance value of the resistor RTI is made smaller than the resistance value of the resistor RT2, a square wave as shown in FIG. 1(b) will be obtained.

FIG. 2 shows a circuit configuration of a second embodiment of the present invention. That is, the diode D2 in the first embodiment
is removed, and when current flows into the capacitor CT from the output end of the rear inverter 3, the resistor R
This is done through the parallel resistance circuit of TI and RT2, but conversely, when flowing to the output end of the subsequent inverter 3, the presence of the diode D causes the current to flow exclusively through the resistor RT2. The time Tl when the output of the astable multivibrator becomes high level and the time T2 when the output becomes low level are as follows.

T2 = 1lbcr RT2 (k3a, k3b are constants) In this embodiment, time T1 is shorter than time T2, but if you conversely want to make time T1 longer when the output reaches /\I level, Just reverse the direction of diode D. In addition, by making the resistors RTI and RT2 variable resistors, the time TI during which the output is at high and low levels,
Of course, it is possible to provide an astable multivibrator in which T2 can be set more precisely.

Next, a low frequency treatment device using an astable multivibrator according to the present invention will be explained. The low-frequency treatment device is a treatment device for treating stiff shoulders and the like caused by stress, nervous fatigue, etc., by stimulating the affected area with a low-frequency pulse current to activate it and relieve fatigue.

FIG. 3 shows the circuit configuration of the low frequency treatment device. This circuit consists of a high voltage generator 1 that is powered by a power battery E whose negative electrode side is grounded and generates a DC high voltage.
0 and a square wave of a selected period, and the square wave generating circuit M V 2 controls the opening and closing of the switching transistor Tr2, and is powered by the power supply battery E, and emits light according to the square wave. Indicator part 1
2, and a therapeutic pulse wave deriving section 1 that derives a therapeutic pulse wave based on the opening and closing of the switching transistor Tr2.
4, a polarity changeover switch 5111 for switching the polarity of the therapeutic pulse wave, and conductors T a I and T a 2 that are in contact with the human body and apply the therapeutic pulse wave to the human body.

In the high voltage generation section IO, the square wave generation circuit M V +
is the astable multivibrator according to the second embodiment, and its output (square wave with a constant period) is given to the base of the switching transistor T r + via the resistor R4, and the switching transistor T r l is opened and closed. do. Therefore, the current flowing from the power supply battery E through the inductance L and the switching transistor T r + to the ground is interrupted at regular intervals, and every time this current is cut off, an extremely large back electromotive force is instantaneously generated in the inductance L. . Therefore, the inductance L
A large current momentarily flows into the high voltage storage capacitor CI through the reverse current blocking diode Dir whose anode side is connected to the high voltage storage capacitor C1.
will be charged to a high voltage. Note that a resistor R5t connected in parallel to the high voltage storage capacitor C1
A series circuit consisting of Zener diodes Z+ and Z2 is a circuit for removing voltages higher than necessary. Figure 4 (a
) shows the voltage state of each part of the high voltage generation section IO, and the directional wave shown at Pl in the figure is the square wave generation circuit MV.
, a large back electromotive force as shown in P2 in the same figure is generated at each falling timing of the inductance L.
This electromotive force causes high voltage storage capacitor C
1 is charged, and its voltage becomes as shown in P3 in the same figure. In this case, the magnitude of the back electromotive force as shown in P2 of the same figure does not depend on the width of the square wave (that is, the time T+ between high levels) shown in P1 of the same figure, but the magnitude of the inductance L and the above square wave. Since it is a product of the steepness of the fall of the wave (more precisely, the time derivative of the current value), it is advantageous to use a narrow square wave from the perspective of saving power consumption of the power supply battery E. . Therefore, the use of an astable multivibrator, such as the astable multivibrator according to the present invention, which can continuously output narrow square waves at arbitrary intervals, is extremely advantageous in terms of power saving.

The square wave generating circuit MV2 is an astable multi-by-break circuit to which the second embodiment of the present invention is applied, in which the resistor RIO, which is not connected in series with the diode, is used as a variable resistor. By adjusting the resistance value of this resistor RIO, the interval (i.e., the time T2 between low levels) of the square wave as shown at P4 in FIG. 4(b) can be changed within the range of 0.5 to 2 seconds. It has become. Such a square wave from the square wave generating circuit M V 2 is applied to the base of the switching transistor Tr2 via the resistor RI3, and the switching transistor Tr2 is turned on for an extremely short period of time with the period of time T2. In this on state, a large current flows from the high voltage storage capacitor C1 of the high voltage generating section 10 to the ground via the resistor R6 and the switching transistor T r 2, and at this time, the voltage at the resistor R6P, which is a part of the resistor R6, increases. The dropped voltage is divided by the resistor R7 and then applied between the conductors Ta1 and Ta2 via the polarity switching switch SWI. That is, every time a square wave is sent from the square wave generation circuit MVP and the switching transistor Tr2 is turned on, the collector of the switching transistor Tr2 is connected to the ground as shown at P5 in FIG. 4(b). level, and each time, the conductor T a l, T a
A pulse wave as shown at P6 in the figure is applied between the two. The pulse current corresponding to the pulse wave applied between the conductors T a I and T a 2 is the conductor T a I,
It flows to the affected part of the human body that is in contact with T a 2, and is this a beard?
Demonstrates therapeutic effects. Also, the switching transistor T
When r2 is in the on state, that is, when a pulse current is flowing through the affected part of the human body, the switching transistor Tr3 is also in the on state, and the power source battery E is connected to the resistor R12, the LED 13, and the switching transistor T.
A current flows to the ground via r3, and the LED 13 emits light.

In addition, when the interval between pulse currents applied to the affected area of the human body by a low-frequency treatment device is 0.5 seconds, the human body feels as if the affected area is being kneaded, and when it is 1.5 to 2 seconds, it feels like it is being tapped. I feel like it's happening. Therefore, a low frequency treatment device requires an astable multivibrator that can output extremely narrow square waves at intervals of 0.5 to 2 seconds, but the astable multivibrator according to the present invention has a high level output. Since the time period T1 during a certain period and the time period T2 during a low level period can be independently and arbitrarily set, it is extremely effective as an astable multivibrator for a low frequency treatment device.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be modified and applied in various ways without departing from the scope of the present invention.

[Effects of the Invention] As detailed above, the present invention introduces a diode into the charge/discharge circuit consisting of a capacitor and a resistor circuit that determines the duty ratio of the output in an astable multivibrator, and When a current flows into
Since this relates to an astable multivibrator in which the resistance value of the resistor circuit is changed depending on when current flows out from one pole, the duty ratio can be set over a wide range without increasing the number of parts. It is possible to provide a stable multi-vibration break.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the circuit configuration and output square wave of the first embodiment of the present invention, FIG. 2 is a diagram showing the circuit configuration of the second embodiment of the present invention, and FIG. 3 is an astable diagram according to the present invention. A diagram showing the circuit configuration of a low-frequency treatment device using a multivibrator, FIG. 4 is a diagram showing the voltage state of each part of the low-frequency treatment device shown in Figure 3, and FIG. 5 is a diagram for explaining a conventional example. It is. Star, Sjl+...Polarity selector switch, T a
l, T a 2... Conductor, E... Power battery, CI... High voltage storage capacitor, z
,,z2...Zener diode, MV+,
MV2... Square wave generation circuit, L... Inductance.

Claims (1)

[Claims] In an astable multivibrator that utilizes charging and discharging of a capacitor via a resistance circuit, when current flows into one pole of the capacitor by using a diode, and when current flows into one pole of the capacitor, An astable multivibrator characterized in that the resistance value of the resistor circuit is switched depending on when current flows out from the poles.